Chapter 4

Live Long and Prosper: Giving Plants What They Need

In This Chapter

Letting in enough light

Figuring out fertilizer, compost, and mulch

Testing for and adjusting pH

Getting the right amount of water and air

Ensuring plant stability

Time to get down and dirty! When you properly prepare the foundation of your garden, making sure plants can get what they need, success follows. The formula’s as simple as that.

Well, maybe not so simple. Is your soil already in great condition? Do you have just the right amount of soil nutrients and rainfall so your garden can thrive without any help from you? Not likely! For most people, improving the soil they have and taking charge of garden watering are necessities if they really want their plants to thrive. This chapter tells you how to give plants a boost.

Some of the information in this chapter may seem like common sense, but read each section carefully, anyway. I describe some techniques and have tucked in some tips that experienced gardeners use to save plenty of time, grief, and money.

The needs of plants aren’t weird or complicated, but you may find that if you omit any of the recommendations in this chapter — either on purpose or unintentionally — trouble can follow. So consider this chapter a bit of a checklist as you get your garden ready for growing! Ready? Here you go. The work you do now can save you a lot of effort later.

Improving a bed or area prior to planting is so much easier than doing so after. Do these tasks early if you can. If you can’t, well then, at least make it a practice to dig really fabulous holes for each plant.

Let There Be Light!

Every plant needs at least some light in order to grow and prosper, but the amount really varies. Mushrooms (which are actually fungi), for instance, can grow in bins in a dim basement or shed; daisies and waterlilies, on the other hand, crave hot, full-on sunshine. Plenty of plants rest in the middle of these two extremes, of course. And some plants, like azaleas and daylilies, grow well enough in less-optimum light but don’t flower well in the shade. In terms of labeling, just remember that full sun usually means six or more hours per day; part-day, of course, refers to less.

You may assume that flowers drink up the light, but actually, the leaves do most of the work. Leaves are the main “engine room” of a plant. For a plant to operate, thrive, and increase in size, all plant parts (except flowers) need to play their roles in photosynthesis. Roots draw in water, but the real energy production takes place primarily in the foliage. Light helps produce the fuel.

Long hours of plentiful sunlight, with varying angles throughout the day, are important so that every leaf — even the ones lower down on the plant — gets the chance to receive light. The good news is that no matter what light conditions your yard has to offer, at least something should be able to grow there. Sun plants and shade plants are labeled, and of course gardeners try to accommodate them. If you need plant ideas along these lines, not to worry — the plant chapters in this book have plenty of suggestions for you.

The warmth of the sun, even more than actual light, inspires flowers to unfurl. Sunlight from the east (morning light) is considered cooler, and western sun (afternoon light) can be scorching. Many plants prefer a site with some morning sun, even until midday, and late-afternoon shade. Other plants are able to endure even the hottest conditions. A plant’s tolerance, of course, varies by region. You can place the same plant in a sunnier spot in the far North than in the South.

If you have plants growing in a spot that receives a blast of late-afternoon sun, be sure to monitor their water needs closely so they don’t dry out. If you find they’re struggling, you can help them by installing something to cast a shadow, such as an arbor, or by planting a tree or large shrub in just the right spot. Even companion perennials or annuals planted nearby can cast enough shade to bring needed relief.

Here are some signs that a plant is getting too much sun:

Flower petals dry out.

Leaf edges look burnt or dried.

Flower color looks faded or washed out.

The entire plant starts to flag.

And here are signs that a plant isn’t getting enough light:

Growth is sparse.

Stems are lanky and spindly.

The distance between leaves, where they’re attached to the stems, is especially wide.

You see fewer flower buds and, thus, fewer flowers.

The entire plant leans toward the light sources.

Some of figuring out the proper location is trial and error — you’re aware that roses like a full day of sun, but you really want that bush to go in the nook that gets afternoon shade. Give the spot a try. If the plant’s unhappy, you can always move it to a more appropriate spot.

Facing the Fertilizer Facts

Fertilizing — that is, supplying your plants with supplemental minerals — is an important part of gardening. I address the specific needs of specific types of plants in their respective chapters. What follows here isn’t the last word on the subject but rather a quick introduction. A well-timed dose of fertilizer really boosts a plant. You can’t argue with success!

Just as a healthy diet allows a person or animal to prosper, so does a good and appropriate supply of nutrients keep a plant healthy and happy. Plants have complex systems in need of chemicals to help them produce their own foods. The three primary plant-growth elements, or nutrients, are as follows:

N (nitrogen): Enhances stem and leaf growth (for most plants, nitrogen ends up being the most important nutrient)

P (phosphorus): Contributes to flower production, fruit production, seed production, and root growth

K (potassium): Ensures general vigor; helps plants resist disease

An all-purpose, balanced formulation contributes to overall plant health. These top three nutrients are usually listed on the back labels of bags of fertilizer that you can buy in any garden supply store. They’re usually listed in order as numbers on the package (N-P-K). A balanced fertilizer (one that contains the three most important elements — nitrogen, phosphorus, and potassium) may show up as 5-10-5 or even 5-10-10. Nitrogen-heavy lawn fertilizer usually has a high first number. You can find are plenty of other variations, depending on the intended use of the fertilizer.

A fertilizer label often tells you which kind of fertilizer is best for your particular garden. If in doubt about your garden’s exact needs, talk to someone at your local garden nursery or supply store. Chances are that their own garden needs aren’t much different from yours!

Certain plants demand more or less of the top three nutrients (for instance, lawn grass loves nitrogen best — consult Chapter 10 if you need to know more about that). But most garden flowers are not specialists, which is why generally fertile soil is desirable and why all-purpose fertilizer is most commonly recommended.

Good soil also contains secondary nutrients, like calcium, magnesium, and sulfur, as well as some trace elements, called micronutrients, that enhance plant health and growth. You usually don’t have to add these nutrients to the soil. However, soil tests sometimes indicate that gardeners should add micronutrients or secondary nutrients, especially calcium (see “Finding out your soil’s pH” for info on soil tests).

Fertilizing good soil is often optional. If you have fertile, organically rich soil, many of your plants may do just fine without it — particularly if you develop the habit of amending the soil regularly (once or twice a year) with more organic matter. If your garden soil is organically rich, it’s fertile and thus should have the major elements. If not, or if you’re pushing your plants to peak performance, you can use plant food or fertilizer, natural or organic, to supply or supplement these important nutrients.

Constantly fertilizing lousy soil isn’t a good idea. Not only is it a lot of work and expense for you, but it’s also a losing battle. Salts build up, plants are never really healthy in the long term, and the soil texture remains poor. You’re far better off increasing the organic matter and just using fertilizer as a nutrient boost for your plants — if they need it. Organic matter — once-living material that releases nutrients as it decays — includes compost, dehydrated manure, chopped leaves, damp peat moss, and ground-up bark.

Depending on what you use, how much, the plant in question, and so forth, the effects of adding fertilizer can be impressive. But they’re not instant. Wait two weeks to a month before assessing the results.

“Feed the soil, not the plants!” is an old gardening adage, and frankly, these are words to live by, folks. You can’t go wrong taking the time and effort to build up soil fertility and structure at least once a year, more often if the opportunity presents itself. Dig in organic matter, add it to every planting hole (except when planting trees and shrubs), top-dress (sprinkle some on the soil surface at planting time), and side-dress (deliver more over the root zone midseason). Why? Because plants and soil organisms like to eat it up and ask for more.

What to feed: The great natural versus chemical debate

Quite honestly, only you can decide which plant food is convenient and successful for your own garden. A plant doesn’t know the difference between one form of an element like nitrogen and another — it’s nitrogen in any case. Some gardeners swear by one fertilizer and use only that kind; other gardeners use a variety of fertilizers. The only way to know which fertilizer you should use is through personal trial and error. That said, you need to know a few things about natural and chemical fertilizers to help you make your decision. Check out Table 4-1 for a side-by-side comparison.

An off-season exercise: Adding organic matter with cover crops

If you have a large flower bed or big vegetable garden, one fairly easy and undeniably efficient way to give it a dose of organic matter is to plant a cover crop at season’s end: You grow plants just to maintain and improve the land during the off-season to prepare the garden for next year.

Sow the cover crop according to the directions on the bag and let the plants grow. It should hog the area to sufficiently thwart weeds. And of course, a cover crop provides plentiful organic matter and limits erosion. Good choices include annual rye, buckwheat, clover, winter barley, and winter rye. Here are some tips based on your region:

In mild-climate areas: Sow the cover crop in mid-fall. When the plants are about a foot high and are still soft and green, dig them in (if practical) or till with a rear-mounted rotary tiller (see Chapter 5 for info on rototillers). Then let the plants decompose or meld for a month or more.

In cold-climate areas: Just plant the cover crop in fall and let winter kill it. The stuff will decompose at least somewhat, with or without snow cover. Till the area in spring, when the ground is workable again. Wait a few weeks before planting the area.

Table 4-1 Differences between Natural and Chemical Fertilizers

Trait	Natural Fertilizers	Chemical Fertilizers
Form	Are organically based; examples	Come in various forms,
	include compost (homemade or	including granules,
	store-bought), manure, fish emulsion,	powders, and concentrated
	cottonseed meal, bloodmeal,	liquids; examples include
	bonemeal, and liquid seaweed	baggedand boxed fertilizers
		in various formulations,
		including Miracle-Gro and
		Osmocote.
Cost and	Pound for pound, are generally	Are usually affordable and
maintenance	more expensive in terms of the	easy to maintain
	amount of fertilizer they provide,
	but they also improve the soil and
	tend to last longer than chemical
	fertilizers
Effects on soil	Tend to improve soil texture and	Do not contribute to long-
	quality	term soil fertility
Presence of	Can include beneficial minor	May or may not contain
secondary	elements	these nutrients; check the
nutrients and		label
micronutrients
Effect on	Feed helpful soil organisms	Usually have a neutral effect
organisms
Rate of	Tend to release nutrients slowly,	Are a fast-acting way to
release	so plants aren’t damaged, but	jumpstart plant performance
	results aren’t always as dramatic	but must be applied correctly
		so they don’t injure or burn
		your plants; special slow-
		release chemical fertilizers
		are the exception

When to feed your garden

Whether you’re using store-bought or natural fertilizer, such as compost or manure, most plants like to be fertilized at planting time, just to get off to a good start. Thereafter, you may fertilize again on a monthly basis. Reduce or stop when fall’s cooler weather arrives. Fertilizer inspires fresh new growth, and you don’t want that then — fall is a time for plants to slow down and approach dormancy, and cold weather can damage new growth. (You should, however, feed the lawn in autumn to stimulate root growth; feeding grass in the spring pushes excess leaf growth that the roots can’t support — see Chapter 10 for details on lawns). Again, for advice on specific plants, read more in the Parts II through V of this book.

If you’re using store-bought or chemical fertilizer, read the label to figure out how to deliver the fertilizer and how much to use. Some fertilizers work best if you dig them right into the soil; others are better delivered in dilute form when you water. The label can also tell you how much to use per square foot of garden area and how often to apply. For bagged organic fertilizer, read the label; otherwise, do some research on your own.

More is not better! (Though if you’re fertilizing with compost, using too much is almost impossible — see the next section.) Plant fertilizer is like aspirin. The right amount is beneficial; too much is harmful. So don’t get carried away. Remember that some fertilizers are types of salt, and high concentrations of any salt can kill plants. Always read the label and follow the directions carefully. To get the amounts right, you may have to pull out the tape measure and figure out how many square feet of lawn or garden you need to cover.

Some gardeners like to fertilize their plants half as much, twice as often. That’s perfectly okay. Just make sure you dilute properly and get your measurements right. (Gardeners often use this technique with roses and many houseplants.)

Compost: More than Just a Fertilizer

Yeah, I also talk about compost in the fertilizer section, but compost is useful and necessary to your garden in so many ways other than as plain fertilizer. Because it’s organically rich, with good texture, compost is just about the best thing you can add to soil. What works best really depends on the type and fertility of your native soil, but you can’t go wrong digging in quite a lot of compost. Compost lightens heavy clay soil and gives needed substance to sandy soil. Less-extreme soils can still benefit.

In any event, half-compost and half-native soil isn’t excessive. Some really keen vegetable gardeners forgo native soil altogether and use 100 percent compost to grow incredible crops. Using solely compost is most feasible in raised beds. Roots relish it. You can get healthier, happier plants.

Don’t use soggy or overly dry compost. Compost should be fully decayed, dark in color and crumbly in texture. This issue is more significant with homemade compost than the bagged, store-bought sort. For homemade, you’re fine if you take it from the bottom of the pile (most store-bought composters have a convenient hatch there). See Chapter 13 for info on how to make your own compost.

Whether you’re planting a new rose, a young perennial, a handful of bulbs, or a bunch of annuals, always dig a hole both deeper and wider than the root ball. This practice gives you an opportunity to make a great new home for the plant, an area the roots can eagerly expand into. Either scoop some compost into the bottom of the hole (where a lot of root growth should occur) or mix compost with the native soil (try a 50-50 mix).

Skip this step of mixing in organic matter for trees and shrubs. The latest studies show that trees and most shrubs do better in the long run if you keep the plants in native soil; in amended soil, they may not grow past the planting hole. However, if you plant them in native soil, they can easily grow beyond the planting hole. (Flip to Chapter 11 for info on trees and shrubs.)

In general, potted plants like a lighter medium. Go ahead and put a handful or two of compost in along with the potting soil, but don’t be heavy-handed. Chapter 16 can fill you in on container gardening.

Quite a few gardeners make their own compost, a process that can take three months to a year to complete. Many gardeners also use a compost bin for this process, like the wooden one in Figure 4-1, though you can just pile the compost in an isolated and sectioned-off portion of your yard. Your compost pile should be kept slightly damp but not soggy. Stirring or turning the material every few weeks can speed up the decomposition process. When the compost is dark brown, is cool to the touch, and has a pleasant “earthy” smell, it’s ready to use.

Figure 4-1: Many gardeners find wooden compost bins attractive and easy to use.

Good material choices for mixing and making your own compost include

Chopped-up leaves (smaller pieces decompose more quickly)

Any young weeds that have not gone to seed

Old lettuce or other salad greens

Prunings from healthy plants

Don’t compost weeds that have gone to seed, any diseased plants, or any plants that have been sprayed with herbicides. Also, animal fats or spoiled meat are not recommended and often attract rodents.

Demystifying Soil pH

The pH (and you can find various arguments about exactly what pH stands for) is the measure of your soil’s acidity, and it’s often a huge area of debate among gardeners. I try to keep this discussion simple so I don’t make your head spin, especially if you have little or no acquaintance with chemistry.

Too low of a soil pH means the soil’s too acidic, and too high of a pH means the soil is alkaline. Generally speaking, you want your soil pH to be on the slightly acidic side for the vast majority of garden plants. Extremes are rarely good. The pH scale ranges from acidic to alkaline — 0 to 14, with 7.0 as neutral. The really good news is that many soils are fairly close to neutral.

Acidic or alkaline soil isn’t bad soil or bad for plant growth per se. But the minerals in the soil that are important to plant growth and health have a tough time getting to the plants when the pH isn’t right for the particular plant. Scientists have discovered that beneficial soil bacteria don’t function well unless the soil pH is relatively close to neutral. These bacteria are important because they break down organic matter and make sure nutrients are in forms that plants can use.

Of course, some plants prefer or are well-adapted to pH levels that are a little more acidic or a little more alkaline. And some soils are naturally so; when in doubt, you can take your cue from the native plants.

Examples of plants that like acidic soil include blueberries, azaleas, rhododendrons, most other broadleaf evergreens, and heather. So in the New England states, where many soils are acidic, you see native blueberry plants. And if gardeners in that region want to grow blueberry bushes (albeit improved, bigger-sized fruit varieties), they should have good luck.

Examples of plants that like alkaline soil include penstemon, dianthus, baby’s breath, and beets. So in the Southwest, where many soils are more alkaline, you see native penstemons. And if gardeners in that region want to grow these flowers (native species or improved selections), they should have good luck.

Finding out your soil’s pH

You can do a little detective work by observing which native plants are thriving and then confirming that they have a preference one way or another.

Or you can run a soil test — use either an inexpensive kit or arrange one of those more-intense tests where you take soil samples from various parts of your yard and mail the dirt in to a lab. The nice thing about doing this more-intense test is that the lab report not only tells you the pH (and a few other useful things, like the nutrient levels in your soil) but also gives you specific recommendations on how to improve or alter your soil. Check with your local Cooperative Extension Service — workers there may be able to run the tests for you at a minimal cost.

Adjusting your soil’s pH

Of course you can adjust your soil’s pH! Gardeners do it all the time when they know their lot in life is extreme soil, or even when they’re just trying to please some special fussy plant. It’s not a big deal. You just dig in something that nudges the pH in the direction you want it to go:

If your soil is too acidic: To raise the pH, dig in dolomitic limestone, bonemeal, or wood ashes.

How much? I knew you were going to ask that! The answer has to do with how much ground you want to alter or improve. If you really need to adjust the pH, I strongly recommend you get that lab-analyzed soil test, because the lab can give you good, tailored directions on what to do and how much amendment(s) to add. Just so you know, though, the general rule of thumb for adding granulated limestone is between 5 and 10 pounds per 100 square feet of garden area.

If your soil is too alkaline: To lower the pH, dig in some acidic organic matter such as peat moss, sawdust, well-chopped leaves from oak trees, or pine needles. Alternatively, you can add calcium sulfate, iron sulfate, aluminum sulfate, or powdered sulfur.

If you don’t let the sawdust, leaves, or pine needles decompose somewhat before adding them to the soil, they can leach nitrogen from the soil as they break down. And too much peat moss can waterlog the soil as well as make it quite acidic. Consider adding no more than one part of organic amendment to three parts soil. You need professional advice on application rates if you decide to go with powdered sulfur or other additives.

Much Ado about Mulch

Mulch is a good gardening habit but not mandatory. But, ooh boy, do the benefits make it worth the effort! A really good job of mulching your garden usually

Inhibits weed germination and growth (and not only are weeds unsightly, but they also they steal resources from your plants!)

Holds in soil moisture, protecting your plants from drying out so fast

Moderates soil-temperature fluctuations (this benefit is especially valuable during that turbulent-weather period in spring when you don’t want your plants to be stressed)

In cold-winter areas, protects plant roots from winter cold and helps prevent frost-heaving, in which plants are literally pushed out of the ground by the natural expansion and contraction of the soil as it cools off and heats up

In hot-summer areas, helps keep plant roots cooler

Depending on what you use, adds a bit of welcome nutrition to your garden as it breaks down

Sound like good enough reasons to use mulch? Yeah, I thought I’d convince you. Read on for the lowdown on mulches.

Knowing your mulches

First of all, I can’t name any “right” or “best” mulch. Benefits vary in different climates and parts of the country. Some mulches are free, right in your own backyard; you can purchase others locally. Experiment to find out what you and your plants prefer.

Table 4-2 provides the basic information you need to know about some of the more popular options.

Table 4-2 Comparing Mulching Options

Type of Mulch	Advantages	Concerns
Grass clippings	Is cheap, readily	Decays quickly, so you have to
	available, and easy	replenish it often; if you use weed
	to apply	killers on your lawn or nitrogen-
		heavy fertilizer, it may adversely
		affect other parts of the garden; can
		turn slimy if you apply more than an
		inch or so at a time; if the grass
		went to seed before you cut it, the
		grass seeds can germinate in your
		garden beds (yikes!)
Wood or	Looks neat and	Pine bark mulch is fairly acidic,
bark chips	attractive; stays where	which you may or may not want for
	you put it; is slow to	your garden; if you apply too deeply
	decay	(over 3") or apply a deep layer up
		against tree and shrub trunks, you
		may create a hiding spot for a bark-
		damaging rodent, especially during
		winter
Decaying leaves	Smothers weeds very	Is not especially attractive; if it
	well; helps hold in soil	contains seeds, they can germinate
	moisture	and become a weed problem; if the
		leaves are soft, like maple leaves,
		the mulch can mat; if it’s acidic (oak
		especially), it can lower your garden
		soil’s pH
Compost	Is free and plentiful if	Makes a good place for weeds to
	you have your own	take hold; fresh compost (especially
	compost pile; adds	if it contains manure or grass
	nutrients to the soil as	clippings) can burn plants
	it breaks down
Peat moss	Looks neat and tidy; is	Can be expensive; if dry, will repel
	versatile — also functions	water; becomes crusty over time
	as a soil amendment
Straw	Is cheap and easy to	Is so light it can blow or drift away;
	apply	may harbor rodents, especially over
		the winter months; isn’t very attrac
		tive for ornamental plantings
Hay	Is cheap and easy to	May harbor rodents, especially over
	apply	the winter months; isn’t very attrac
		tive for ornamental plantings;
		probably contains weed seeds!
Gravel,	Has a nice, neat look	Can allow weeds to sneak through;
pebbles,	(though not “natural”);	provides no benefits to the soil
or stone	is easy to apply; won’t
	wash away easily and
	will last a long time;
	doesn’t need to be
	replenished over the
	course of a season
	in colder climates
Plastic (garden	Keeps weeds at bay;	Watering and feeding is hard (you
plastic, black	holds soil moisture and	need to cut openings for plants); can
plastic)	warmth in	be difficult to apply unless you’re
		doing an entire area at one time;
		isn’t very attractive

How to apply mulch — and how much

If you’re ready to start applying mulch to your garden, here’s what you need to know to ensure you get the best possible use of your mulch:

When you plant: Applying mulch right after planting something is easy. Use a shovel or scoop with a trowel. Spread the mulch over the root-zone area but not flush up against a plant’s base or main stem (which can smother it or invite pests or disease).

Depth depends on the sort of plant. Annuals and perennials are fine with an inch or so of mulch; shrubs, roses, and trees need 3 or 4 inches or more.

During the growing season: Add more mulch midway through the growing season or whenever you notice it’s depleted. You may have to get down on your knees or wriggle around a bit as you try to deliver it where it’s needed without harming the plant or its neighbors. Again, use less for smaller plants, more for bigger ones.

In the fall or for winter protection: Depending on the severity of your winters and the amount of snow cover you expect (a blanket of snow can act as a protective mulch, actually), you want to cover an overwintering plant well. You can cut down perennials first and then practically bury them under several inches of mulch. You shouldn’t trim back shrubs and rosebushes at this time, but you don’t have to be as careful as you were with midsummer mulching because the plant is no longer growing actively. For freezing winters, 6 or more inches around the base of these is good.

These amounts are guidelines only. You have to tailor them to your climate, growing season, and specific plants.

To limit erosion, don’t excavate large areas that are on a slope without planting or at least mulching soon, especially during the spring, when rainy weather can cause washouts.

Water, Water Everywhere: Tackling Watering Issues

Sure, without moisture, plants die. Everyone knows that. But you may not know why water is so incredibly vital. The answer is threefold, actually:

Sufficient water pressure within plant tissues creates turgor, or rigidity, so the plant can stand up. A plant without turgor pressure collapses.

Water keeps nutrients flowing through the soil, the roots, and the plant parts as they should; it keeps the show going.

The show is the chemical process of photosynthesis, which you no doubt remember from biology class in school. The plant uses light, carbon dioxide, and water to make sugar (a pretty impressive trick). Without photosynthesis, plants can’t grow or develop flowers or fruit.

Keeping a close eye on your plants is easier said than done, of course, but the following sections tell you what you need to know, to keep in mind, and to watch out for when evaluating just how much moisture your garden needs.

Providing plants with the right amount of moisture

How do you make sure your garden has the right amount of moisture? Relying on natural rainfall would be nice, but natural rainfall is hard to count on (though it does kindly water your garden for you from time to time). Gardeners always seem to have to supplement the moisture, a little or a lot. You just need to keep an eye on things and pay attention to your plants. Read on for the warning signs of too much or too little water.

On the dry side

If you know what to look for, you can figure out your plants’ watering needs. Plants actually prioritize when water-stressed, so look for the early warning signs:

1. If a plant isn’t getting enough water, flower petals and buds are the first things to be jettisoned (or fruit if it has developed), because making and maintaining them takes so much energy and water.

2. Next to go are the leaves, which shrivel.

3. Then the stems flop.

4. Underground, the roots go limp.

Obviously, if your garden is in this condition, it needs more water.

Bogged down

Telling when a plant doesn’t have enough water may seem to be a snap, but keep in mind that there’s definitely such a thing as too much water. If puddles form in your garden or an area of it’s quite soggy, all the pores in the soil fill. When this happens, no free oxygen, which needs to get to the roots, is in the soil (See “Air! Air! Plants Need Air!” later in this chapter).

Meanwhile, some plant diseases (like mildew and blight) travel via water and can easily develop and spread in soaked conditions. Sodden roots blacken and rot, and all the aboveground growth subsequently dies. Garden plants in these circumstances, of course, need less water. See “Dealing with drainage problems” later in the chapter to find out what to do.

Unfortunately, an overwatered plant looks the same as one that’s underwatered! The reason is that an overwatered plant is actually suffering from dehydration because the roots have been damaged by too much water (actually, too little oxygen, because the water has displaced the oxygen); the roots can’t absorb water, so the plant wilts. One difference is that overwatered plants don’t recover from wilt when you apply additional water, but underwatered ones generally do.

Determining which watering system to use

The amount of water your garden needs depends on what kind of soil you’re using, what your climate is like, and what kinds of plants you have. Shallow-rooted plants, for example, need more water than deep-rooted ones for the simple reason that they’re closer to the soil surface, which dries out more quickly in the heat of the sun. Deep roots can reach the more consistently damp lower soil layers.

For many gardeners, getting enough water to their gardens is the biggest gardening challenge. If you’re crunched for time or have a large area to water, installing in-ground sprinklers and irrigation systems may be a good idea. Employing the use of a regular watering system, such as drip irrigation or an in-ground system, is the best approach to ensuring a consistent moisture cycle to grow happy, healthy plants. However, in-ground watering systems tend to be expensive and should be installed by professionals. If you’re looking for suppliers of irrigation systems, the companies in the Appendix may be a good starting point.

Of course, you can always water your garden yourself, by hand, and really that’s a great way to do it, because you can personally inspect each plant. For details about equipment like soaker hoses and portable sprinklers to help you with your watering, please check out Chapter 5.

Whether you water by hand or use a system, here are some things you may want to keep in mind:

Watering your garden early in the morning, before the sun is fully overhead, is usually best. Watering at night can make plants susceptible to diseases that cause them to rot.

Some plants in your garden, such as melons, may require more water than others, in which case watering by hand is probably best.

If you don’t have an outdoor spigot close to your garden for convenient hose hookup and watering, a rain barrel may be a good substitute for keeping water close to your garden. Various mail-order suppliers sell rain barrels.

Make sure you get a barrel that’s tall enough so pets can’t get in, or put on covers to reduce drowning risks to pets and children. To keep mosquitoes out, use products like Mosquito Dunks, which are donuts of a type of bacteria that’s harmless to humans but deadly to mosquito larvae.

Usually, watering the soil rather than the leaves is best because the roots are what absorb water, and they’re in the soil. Also, wetting the leaves can result in more disease problems. Still, on a very hot or windy day, watering the leaves can reduce wilt and lower leaf temperatures.

Unless you have a very large garden, sprinkler heads that you attach to garden hoses are usually better suited for lawns than gardens. If you decide to use one, make sure the sprinkler covers the entire garden area evenly and doesn’t water things you don’t want watered, like your lawn furniture or windows.

No matter what kind of garden you have or which watering system you use, infrequent deep soakings are better than frequent shallow waterings.

Cutting back on watering

Even if you don’t live in an area experiencing drought, you don’t want to waste water, no matter what you pay for it or how much you have to use. Remember that for most efficient delivery, water in early to mid-morning — after the dew has dried but before the heat of the day sets in and much of the water evaporates. And mulch, mulch, mulch individual plants and entire beds to hold in the water right by the roots, where plants most need and appreciate it. I go into more detail about mulch earlier in the chapter in “Much Ado about Mulch.”

Wherever possible, build up a basin of mounded-up dirt or mulch around the edge of the rootball of each plant at planting time. Water goes right in the basin and soaks directly down into the root system instead of running off onto the lawn or driveway or elsewhere where it isn’t needed.

The method of delivery can also save water: In-ground irrigation systems are wonderfully efficient, as I mention earlier in the chapter, and soaker hoses are also good. Drip systems shouldn’t produce any appreciable runoff on slopes. And although some sprinklers are good, others are very wasteful. Check out mail-order catalogs that specialize in types of sprinklers. They’re filled with good information on how to choose the right ones.

Depending on what kind of soil you have and how well it absorbs, you may find it worthwhile to run the water slowly rather than fast, and perhaps ten minutes on, ten minutes off — either or both of these techniques often drenches an area quite efficiently with little waste.

Deciding whether you need professional help

Valves, risers, timers, controllers, moisture sensors, and pipes, oh my! If all these parts and how they should go together makes your head spin, hire someone. Hire someone who’s done it hundreds of times; find such a contractor via your local garden center, in the yellow pages, or through a reference from a friend or neighbor. (Get a written estimate for the work, labor, and parts, and check references.)

However, if you’re an affirmed do-it-yourselfer, handy, and confident, by all means, install your watering system yourself. Check with your local utility companies — gas, water, and electric — (if the system’s underground) before doing any digging to avoid costly and potentially dangerous accidents. Detailed information and advice is available (where else?) in Lawn Care For Dummies (Wiley), by Lance Walheim and the editors of the National Gardening Association.

Rain gauges are useful for measuring water when you apply it with overhead sprinklers. For drip systems, run them for an hour or two and then dig down into the soil around the plant to see how far down and wide the moisture has penetrated. Run the system longer if it hasn’t yet penetrated deep enough to reach the root zone. After you do this exercise a few times, you should know how long to run the system each time you water.

Another way to cut back on the amount of watering you need to do is to use drought-tolerant plants in your garden. Gardeners in the Southwestern portion of the United States are particularly good at this type of gardening, largely through necessity. Drought-tolerant plants include cacti, succulents, ceanothus, rock rose, native dryland plants and their cultivars (such as penstemon and gaura), and deep-rooted perennials like prairie natives and their cultivars (such as baptisia, liatris, black-eyed Susans, and purple coneflowers).

Dealing with drainage problems

You know you have a drainage problem in your garden when heavy or even moderate rain leaves puddles that take forever to drain. Or you may find out, to your dismay, that under a few inches of okay soil in your yard is a stubborn layer of hardpan (most people discover this water-resistant barrier — often packed clay — when they dig a deeper-than-usual hole, say, for planting a big shrub or a tree).

Really damp areas (especially in humid periods or in shady spots) are slow to evaporate water, whether from rain or from your sprinkler. Then plant diseases can get begin, particularly on foliage. The answer here is to try to improve the air circulation: Prune overhanging growth and give individual plants more elbow room. And when you’re in charge of watering, supply it to the roots instead of allowing it to splash the entire plant.

Obviously, bad drainage isn’t good for any garden plant, not just trees and shrubs. If you’re smart or lucky, you can deal with the problem before you plant or redo an area. Here are some options, from the simple to the high-tech:

Try improving the soil. Dig in lots of organic matter. Soil with a high organic-matter content allows excess moisture to drain through while absorbing needed water. Sounds paradoxical, but it’s true. (For info on improving soil with compost, check out the earlier section titled “Compost: More than Just a Fertilizer.”)

Build and garden in raised beds. You control the soil within, and thus it drains well and your plants are happy. Problem averted.

Create a rain garden or a bog garden, and plant only water-loving plants. Water-loving trees and plants include maples, willows, astilbe, ferns, filipendula, beebalm, mint, various sorts of irises, and canna.

Route water flow away from the garden area. Just get out there with a trowel or shovel and create some diversion channels. Of course, you don’t want to send the problem to another important part of the yard or foist unwanted, excess water on your neighbor. Send it down the driveway and on into the street, or into the gutter. This water needs to head for the storm drains. (If this plan isn’t practical, dig a hole nearby, fill it with gravel, and route the channel there.)

Fertilizer runoff can harm rivers and streams, so if you use this technique, be especially careful that you don’t use excessive fertilizer and that you apply it at recommended times so the plants use the nutrients rapidly. See the earlier section “Facing the Fertilizer Facts” for info on proper application.

Make a gravel channel. Follow the advice about rerouting water flow, but dig the channel somewhat deeper and fill it with crushed gravel or pebbles. You can hide it from view for some or all of its length by scooping a little soil over it. It’ll still do its job of slowly but surely taking the water away.

Use perforated plastic pipes, lightly or deeply buried, to divert the water to where you want it to go. Home supply stores sell pipes specifically for this purpose. These pipes usually come in various forms and sizes of plastic; clay tiling is also available, but it’s too heavy and expensive for most homeowners.

If the problem is severe and you can’t seem to solve it, drainage tiles, a French drain, or a curtain drain are options. Installing one of these systems can be a very expensive and involved process. Hire someone experienced to advise you, explain the options, and install.

Air! Air! Plants Need Air!

A sometimes overlooked necessity for plant life is air (and not just carbon dioxide). Without air, plants struggle and perish. Yes, the free oxygen in the air is part of the photosynthesis recipe, produced by the plants themselves, but another practicality is even more visible here. Air movement around your plants prevents disease, especially fungal diseases that gain a foothold when the air is too “close” and humid and when wet leaves can’t dry or don’t dry quickly.

Underground, oxygen between the particles of soil is important. Plant roots, or more accurately, their little root hairs, are busy. They take in that oxygen, absorb water, and then release carbon dioxide. If this process is thwarted, as in waterlogged soil, the roots can’t function properly, they begin to rot, and the plant surely suffers.

I’m not suggesting you set up a fan out there in your garden, but here’s what you can do to make sure your plants are getting plenty of air:

Don’t let soil get compacted. If it’s quite wet, don’t walk on it or dig in it. Loose soil is airy soil.

The addition of organic matter, especially in dense clay soil — something I keep harping on, I know, but it’s so important — helps keep it aerated.

Never kill an earthworm. Earthworms help break up and aerate your soil. Rejoice in their presence! Welcome them!

Make sure your garden is well-drained (see the preceding section on drainage).

Don’t crowd your plants together in the garden bed if they’re susceptible to mildew or black spot. Give everyone a little elbow room!