part0016

In this section, we dive into watering your plants. (Get it?) Anyway, we’re going to discuss how and when your plants should be watered, along with what nutrients to feed your little ones to keep them growing strong. Nutrients are classified as either macronutrients, which plants need in large amounts, or micronutrients, which plants only need in small amounts. You’ll also learn how to troubleshoot and correct basic nutrient deficiencies your plants may experience during their growth cycles.

Unlike we humans, who eat and drink for nourishment, plants can only drink, either by taking in water through their roots or moisture from the surrounding air via their leaves. They use nutrients found in the soil and carried through water to power their cellular machinery, and they produce energy from sunlight, water, and CO2 during photosynthesis. Water is critical to proper plant growth and health, but it must be the right type administered in the correct amount and at the proper frequency. One of the biggest mistakes first-time growers make is overwatering and overfeeding their plants. When it comes to watering and feeding your plants, more is definitely not better.

Watering systems can be active or passive. Active systems actively deliver water to the growing media or directly to the plant roots. Passive systems typically employ some type of water reservoir that the roots can access as needed. An example of a passive system is the hempy bucket, which is a container filled with growing media. Instead of drain holes at the bottom of the container, there is a drain hole a few inches from the bottom. This allows the bottom layer of soil to remain wet, providing a buffer against drying out and inviting roots to this moist area. Active watering can be drip irrigation, hydroponic, or aeroponic. We’ve talked about hydroponics briefly, and how a nutrient solution is supplied directly to the plant roots, which dangle in water. Aeroponic systems allow roots to hang in the air; nutrients and moisture are sprayed on them in a fine mist. Drip irrigation systems, which can provide a steady flow of water for a set amount of time, have been used for decades in the landscape and gardening industries. A reservoir, a timer, and a pump are all that are needed to start a basic drip irrigation system. Most indoor growers will want to start off by hand watering or using a simple drip irrigation system.

Unless you are running an automated system that has been optimized through trial and error, it can be a challenge to know how much water to use when watering. With most non-succulent potted plants, you want to water until some liquid emerges from the drain holes. Water contains nutrients, which cost money, so you want to get enough to the plants while giving the floor as little as possible. During the seedling phase, you want to make sure your plants are getting enough water without saturating their roots. Many indoor growers water with half the amount of water that would fill the growing container. For example, a plant in a one-gallon pot would get half a gallon of water each watering. Cannabis roots are highly susceptible to fungal diseases that occur when conditions are too wet or stagnant. It’s for this reason you want to avoid overwatering or using poor soils that won’t drain or lack appropriate airflow.

Though often overlooked, the temperature of the water used for your cannabis plants is critically important. Your watering solution should be between 68°F and 74°F. If it’s too cold or too hot, it can shock the root system and prevent it from developing. Warmer water contains less dissolved oxygen, which is a major carrier of nutrients. Fewer nutrients generally means less growth. More often, at least in much of the United States, your irrigation water will be too cold for the plants. When the water is too cold, the plant may have dark leaves or stems and branches that turn purple. Although they are often pretty to look at, these are signs the plant is not converting phosphorus, a macronutrient critical to growth and flower development. Typically, micronutrient deficiencies will follow. If possible, after mixing it with nutrients (see Plant Food ), allow your watering solution to remain in the growing environment for 8 to 12 hours, out of direct light, to acclimatize it prior to watering your plants. You should monitor the temperature of the watering solution to verify it’s within the appropriate range before you water. A standard kitchen probe thermometer is all that is needed. Watering at the wrong temperature, even once, can take a long time for a plant to recover from, so taking this step is good insurance.

The pH scale runs from zero to 14. Seven is neutral. Substances with levels from zero to 7 are considered acidic, like vinegar and tomato juice. Substances with levels from 7 to 14 are considered basic or alkaline, like baking soda, soap, and many cleaning products. Cannabis plants prefer soil pH levels just under neutral, around 6 to 7. Soil pH will largely be determined by the pH of the watering solution you use. Depending on your grow, you may be using water alone or with added nutrients. Nutrient uptake is pH dependent. Not only must you supply your plants with the correct nutrients in the right amounts, but you must also provide the right pH range so the roots are able to take up those nutrients from the soil. To test pH, you can use disposable color-change test strips or invest a few dollars in a digital pH meter. Meters are nice if you do a lot of testing but require periodic recalibration with chemical pH standards. There are dedicated soil pH meters available. To use these, you stick the probe directly into the soil for a continuous reading. These tend to be somewhat inaccurate or unreliable, though, so it’s best to focus on the pH of your watering solution.

Water hardness is another fundamental concern. This often has to do with the particular region you live in and where your water is sourced from. Hardness measures the degree of mineralization of the water in the parts per million (ppm) scale. Water with a hardness of zero ppm is pure and contains no solids whatsoever. Water with a hardness of 100 ppm has 100 parts dissolved solids, mostly minerals and nutrients, for every 1 million parts of water. Minerals are helpful, but plants only need them in minute amounts. Hard water leads to alkaline soils, preventing nutrient uptake and normal growth of the plant. Buildups of calcium and magnesium in the root zone are common to plants watered with hard water. If you live in an area with hard water, you might want to consider using a deionizer or reverse osmosis system on your water, which reduces the presence of solids to nearly zero ppm. Starting with a baseline hardness of zero ppm for your water allows you to precisely monitor the ppm levels of your watering solution, as nutrients, as well as minerals, are reflected in the ppm measurement. You can then compare these initial solution readings to readings from your runoff or drainage to ensure the plants are taking up the right amount of nutrients. In general, the level of nutrients in your watering solution should be lower after it traverses the root zone. If it is the same, it means the roots are not taking up the nutrients properly, most likely due to the pH level. If the level of nutrients in your watering solution is higher after going through the root zone, this signifies nutrient accumulation, also often due to improper pH. If this is the case, you should thoroughly flush the soil with zero-ppm water.

DOES MY PLANT NEED WATER?

How frequently you should water your plants changes with the conditions of the grow room, the growth phase, the container, lighting, and other factors. During germination, you want to keep the soil and air conditions very moist; you can start to dry things out in the seedling phase, during which you should have moist soil an inch or two below the surface. Once it starts to feel dry deeper than this, it is time to water. Stick your finger in the soil about two inches down. Is the texture moist or dry and crumbly? If it feels dry or the texture is crumbly and doesn’t cling to your finger, it’s probably time to water. If it’s moist and sticks to your finger, you can probably wait a day or two. When you water in larger pots, be sure to water in concentric rings outward from the main stem and not just at the base of the stem.

You should also look at the leaves. How is the color? Are they a bright, vibrant green or starting to yellow or fade? How do the leaves hang? Are they full and sticking out, or are they drooping and starting to curl? Drooping leaves are the most obvious sign of a plant needing water. Check the container weight to confirm by lifting it if you can do this safely and ergonomically. Growing containers lacking water are remarkably light compared to those holding water within the soil. Oftentimes, in as little as minutes after watering, previously drooping leaves will have already returned to their full, upright, and extended posture.

As your plant matures into the vegetative phase, you can allow the top few inches of soil to dry out between waterings and maintain this level throughout flowering. You’ll still want to monitor closely, as changes in lighting or growth phase may require the plant to take in more nutrients and thus water from the soil. Overwatering can also occur and is often indicated by leaves curling under.

What, when, and how you feed your plants has a major impact on plant health and bud yields. Cannabis plants require varying levels of macronutrients and micronutrients depending on their stage of growth. Many ambitious amateurs tend to err on the side of overfertilization when starting new indoor grows, often with disastrous results. Fertilizers and plant food are beneficial and often necessary for rapid growth and development, but using too much can stunt growth, misalign soil chemistry, and injure plant tissues.

Macronutrients are the “Big Three” nutrients needed in relatively large amounts by your plants: nitrogen (N), phosphorus (P), and potassium (K). When you purchase nutrients and fertilizers, they will typically have a nutrient profile consisting of three digits corresponding to the percentages of N, P, and K respectively in the product. For example, a nutrient mix with a 5-5-60 profile consists of 5 percent nitrogen, 5 percent phosphorus, and 60 percent potassium. Nitrogen is important for vegetative growth and building strong leaves, stems, and branches and is needed in large amounts by young plants increasing in green biomass. Phosphorus and potassium are critical to root development and are crucial during the flowering stage.

Most quality soils contain enough nutrients to sustain a seedling for the first four to five weeks of its life. Most growers will then switch to a nitrogen-rich product for the first few days of flowering, then to another product more conducive to flowering, containing higher levels of phosphorus and potassium and lower levels of nitrogen. This is then maintained until 7 to 10 days prior to harvest.

When growing in soil, food for your plants will come in two basic forms: amendments that are mixed in with the soil, such as humus, peat, and synthetic fertilizers; and concentrated liquid nutrients that are diluted with water and used to irrigate the plants. Many growers use a combination of the two, allowing the soil amendments to act as a foundation of nutrients and the liquid nutrients to act as an added blast of nutrients every so often. Liquid nutrient fertilizers, when used in conjunction with soil, should typically only be applied every second or third watering or as little as three or four times throughout the plant’s growth stage. Check the manufacturer’s instructions for dilution and watering frequency based on your plants’ growth phase. Consider a small investment in an EC/TDS meter to check the level of nutrients in your soil. EC stands for “electrical conductivity” and is a measurement of the ions in the soil. The more nutrients present in the soil, the higher the EC/TDS value will be. Many cultivators will check the EC/TDS and fertilize accordingly. For example, if a ready-to-use liquid fertilizing solution targets 1,200 ppm TDS and the soil shows a 400 ppm TDS reading prior to watering, you would deduct the 400 ppm from the 1,200 ppm and only feed an 800 ppm solution. This would most likely require diluting the 1200 ppm solution or making a new solution at 800 ppm. Remember that soils like to trap and accumulate both macronutrients and micronutrients. This unique property provides soil with life-giving powers, but excess accumulations of nutrients in pots or other containers can quickly lead to toxicities for your plants.

Your plants’ roots need room to grow throughout their container. If roots lack adequate space, they may start to grow in and on themselves, and your plants will become “root-bound,” which is detrimental to the production of quality buds. Make sure your plants have adequate room to expand, and transplant as often as necessary to accomplish this. Periodically check the bottom drain holes for signs of root crowding, such as the emergence of thick roots or blockages of many crisscrossed roots.

If you’re interested in other enhancements for your root zone, consider the use of organic compost teas or mycelium. Compost teas contain beneficial organisms that live in and break down the soil, making nutrients readily available to your plants. Using mycelium in your garden can also have big rewards and only requires a sprinkling of store-bought mycelium powder when you prepare your soil.

TAKEAWAYS & EQUIPMENT LIST

Another one bites the dust! Well done.

In Step 8: The Nutrients, we made a splash talking about watering and feeding your plants.

Here is what we covered:

• How to use active and passive watering systems

• The optimal temperature, pH, and purity of irrigation water

• What signs to look for to determine if your plant needs water and an ideal watering schedule

• What and how to feed your plant

• The role of macronutrients and micronutrients in a plant’s overall health

• How to create a healthy root system with good oxygen, warmth, and moisture

SHOPPING LIST FOR NUTRIENTS

EC/TDS meter for water/soil

High-quality soil mix with beneficial organisms and/or high-quality nutrients

Measuring cups for nutrients

pH meter for water/soil

Water—reverse osmosis (RO) or deionized (DI) preferred

Now you’re ready for Step 9, which will detail how to care for your growing plants. You’ve got the basics of your setup down, now it’s time to learn what your routine will look like.

STAGE	RECOMMENDED NPK PROFILES
Seedling	N/A
Vegetative	6-4-4 or 10-5-7
Flowering	3-10-10 or 2-8-4