Chapter 6
Cannabis in Containers

An outdoor container garden can be grown on a deck or interspersed with other cover/companion plantings within your regular garden. This can be one of the best ways to start off growing cannabis. It allows you to try growing without a large outlay in labor and materials, and allows easy moving of the plants as you learn how the sun moves around your property during the growing season.

Considerations

If you are thinking of a small outdoor grow in containers, the first things to look at are how close your neighbors are and how accessible your deck or backyard garden is to passersby. Ideally, this area is fenced, with a locking gate.

Light

Another big factor in urban or suburban grows is the presence of artificial light. Do your neighbors have nighttime security lights or bright porch lights? Are there streetlights on all night? Cannabis’s flowering is triggered by light cycle, whether natural seasonal duration of the sunlight or by artificial light, so continuous nighttime light can be a problem.

Proximity to Schools

Check into the laws in your particular state; many legal medical growers have been dismayed to find out that growing (even indoors) within 1,000 feet of a school is a prohibited activity. This is something far better known ahead of time, as the legal implications can be very troublesome.

Potential Thieves

Even if you are growing legally on your own property, remember that your cannabis will be very attractive to thieves. The best way to protect your plants is to have them blend in to an existing container garden or a mix of containers and larger varied plants that are perennial, larger, and growing in the ground.

An array of different greens and leaf types (think of how camouflage works) makes it much harder for the nongardener to spot cannabis. Most cannabis thieves are not gardeners; that is why they are out stealing yours!

Container Types

When choosing a container for your cannabis, there are three important rules to remember:

  1. The container must be able to hold soil.
  2. The container must be large enough for the plant to grow to maturity.
  3. Water must be able to drain easily from the bottom of the container so the soil does not get waterlogged.

The container can be any shape so long as it can fulfill these three essentials. There is an enormous variety of useful containers available. Pick your containers based on availability, cost, and efficiency. The size of containers you use for mature cannabis plants will, in part, be determined by how big you can allow the plants to get. If you live in a suburban townhouse and are growing a few on your deck, you will want to keep the plants small to avoid detection and theft. Cannabis plants are somewhat like goldfish; they will generally grow to fit their space. A ten-foot sativa towering on your balcony will be noticed by even the most unobservant passerby.

Containers can be purchased at your local nursery or hardware store. The most common kinds available are traditional oak barrels, pots made from reconstituted paper, terra cotta, ceramic, wood, plastic, and resin. If you are planning to grow your vegetables in a container for several years choose a good quality one that will last. Containers need to be cleaned on a regular basis to keep them looking good, as well as pest- and disease-free, so choose a container that you can take care of easily.

To save money, you can recycle items that are no longer fulfilling their original purpose. Some ideas for small containers for growing plants, for example, are tin cans, bricks with a center opening, milk cartons, a bucket, or an old cooking pot (a great place to use that kitchen pot that got burnt and will never come clean again!). When you purchase garden pots, there usually are holes in the bottom of them already; however, if you are recycling a container, make sure you make at least one good drainage hole so excess water can easily drain.

Some popular containers include:

Small Containers

Say you plan to grow four plants on your deck. You have access to water, and ideally already have some general plants out there, including herbs and container tomatoes. To simplify, you start with clones, so you know they are females. You have identified the sunniest spot and checked that taller buildings do not overlook your deck.

Money Smart

The least expensive way to go is to use recycled nursery pots. These can come from a friend who has recently purchased and ground-planted large shrubs, or nurseries will frequently give used plastic pots away or sell them for a nominal fee. Ones used for baby trees can be quite large—up to fifteen or twenty gallons in size. If you are using recycled pots, give them a thorough cleaning, including wiping with a light bleach solution and then rinsing with clear water. This will eliminate any harmful fungi or bacteria that may have been in the previous soil. Most nursery pots lack enough drain holes, so take a drill to the bottom and double the drain holes. Put in a bottom layer of drain rock to improve drainage.

Since you are keeping your plants small, go for the five-gallon pots; the taller variety seems to work better than the shorter, fatter version. They both hold five gallons of soil, but the taller pots suit the growing style of the cannabis a bit better. Of course, if all you can find are the shorter pots, cannabis will accommodate you and adjust itself accordingly.

Wine Barrels

Another, more elegant, solution for containers is recycled oak wine barrels. In the early heyday of cannabis growing in 1970s Mendocino County, wine barrels were cheap. The California wine industry was growing rapidly at this time, and the barrels were not typically reused once wine had been bottled. If purchased directly from the winery, the whole barrels also had the interesting benefit of frequently containing up to a gallon or so of good wine to be salvaged! Now wine barrels are sold as half barrels for $20 and up.

While wine barrels are attractive, breathe well, and have excellent drainage, they are also expensive, hard to clean, and will eventually rot. If you are going to use half barrels, make certain to get your drill out and make multiple drain holes in the bottom. The wine barrels hold more soil, so be prepared for your plants to get quite large. With the right feeding and watering, a sativa cross grown in a half barrel can easily reach eight feet in height.

Keep It Simple

It might seem obvious, but be careful and think ahead when using power tools to make drain holes. Drilling through the bottom of a container is simple until you figure out you just drilled through too far and made holes into your (or your landlord’s) nice deck. Flip the container over for this activity!

Plastic Barrels

Less elegant, but much cheaper and lighter to move when empty, are food-grade 30-gallon plastic shipping barrels. Each barrel can be cut in half to yield two containers. The plastic is very tough, but still easy to drill through and cut. If you are lucky enough to live near a port, do some telephoning and find a source for the used barrels. They must be rated food-grade, which means they originally contained something like soy sauce and not motor oil. Used barrels are sold clean and typically the whole barrel will cost somewhere between $8 and $15. The plastic barrels will last for years, unlike the similar-sized oak half barrel.

Sometimes food-grade barrels come in bright colors like light blue, but the plastic will hold paint well. It is advisable to paint the outside surface with more natural colors (various greens, light browns; think camouflage again) so the barrels don’t stand out too much. If you are planting a mixed garden totally in barrels, this is less of an issue. It’s obviously not a good idea to have just the cannabis in bright containers, as it will draw attention specifically to the cannabis. You want the cannabis plants to blend in with your other garden plants.

Again, as with the half wine barrels, the plants will get quite large with so much growing space. Outdoor growers who experience vole or gopher problems with direct ground planting frequently use food grade barrels. The barrels can be half-buried in the ground for less visibility. If you use this option, be sure to make extra drain holes, as the barrel will drain more slowly when buried. If voles or gophers are a problem, place a protective screen of chicken wire over the surface of the half-buried barrel to prevent rodents from top burrowing into your container.

Grow Bags

Grow bags are another economically sound container solution for the grower. The main disadvantage is the need to support the bag and plant as the plants get large. These are mainly advised for the grower with a larger crop. They also come prepacked with peat or compost, so you have less control over your soil mix. Peat-free composts are improving, but most people still find peat bags give the best results.

If you are starting out in coldish spring weather, warm the bags. Either store inside a heated room for a few days or cover with black plastic sheeting in the sun. This will take the chill off and warm the compost. Young plants crave warmth. Preferably wearing gloves, shake the bags hard to loosen the compost and prick the bottoms with a knife or a garden fork for drainage before putting them in their planting positions.

One disadvantage of grow bags, unlike hard pots or barrels, is their need for support. You can either set up supports for tall plants against a wall, hammer stakes into the ground around the grow bag, or purchase a self-supporting grow bag frame. You will also need to position your watering aids before planting. Trying to do this later will disturb the plant’s roots and slow growth.

Once the bags are set up, cut a cross in the center of the top of the bag the size of the plant’s interim pot, peel back the plastic, unpot the plant, and plant. Cut a pot-sized cross in the top of the bag between your centered plant spot and the edge and sink a four-inch plastic plant pot into the compost up to its rim in each position. Direct the water and feed into these pots and it will quickly soak down to the bottom of the bag.

Keep It Simple

If you have more than a few bags, it is worth investing in a drip feed watering system with a timer. Cannabis has an enormous appetite for water and will quickly fill the bag with roots, which, unlike soil, do not retain water. Bags can dry out much more rapidly than barrels.

Smart Pots Aeration Containers

Smart Pots aeration containers are a recent innovation in containers that are being used very successfully by many growers. They are made from a super-strong black fabric material that warms up quickly in the spring, giving the plants a friendly environment for rapid growth. The porous nature of the fabric provides excellent breathability, favorable for root development, and allows heat to escape through evaporative cooling when the weather gets hot. The fabric also drains very well.

Of interest to the outdoor grower is that the fabric base will contour to and establish capillary contact with the soil. Of interest to both outdoor and indoor growers, Smart Pots come in many sizes, from small to very large, so you can customize to fit your growing space.

Raised Beds

Depending on space and privacy considerations, you might consider a large raised bed. Raised beds are structures that have four sides and hold soil. They are a great option for a small space, for areas with poor soil, or for a hillside garden. If you want to grow in a moist area that has poor drainage, the raised bed will allow for better drainage. If you have a sloped or terraced garden site, raised beds will help define these areas and make it easier to grow plants in the more difficult to reach areas. The advantages are many: lots of food and good drainage, yet the roots are protected from burrowing rodents by the wire bottom of the container.

Another great reason for using raised beds is that the bed can be made to any height. If you have physical disabilities, have limited mobility, or cannot bend easily, the raised bed can work very well for you. Make sure it is built to the height that works best for you. If it is a low bed, adding a ledge on the top will allow you to sit while gardening. And the ledge is great for older gardeners or those who cannot easily get down on hands and knees to plant or weed.

Four large cannabis plants can be grown in an 8 × 8 raised bed. If you have sufficient sunlight and pay attention to feeding and watering, normally expect a yield of a pound to a pound and a half from each plant.

Prep Work

First, plan for the seasonal movement of the sun, and mark out your square. Second, check the soil drainage where you plan to locate the bed. Do a small percolation test by digging a few small holes one foot in depth and fill with water. Monitor to see how quickly the water drains. If it stands for hours like it is in a bucket, you have poor drainage and probably compacted clay soil. If you have a small garden tiller, do a light pass over the square to improve drainage; otherwise, do a little aerating with your garden fork.

Building a Raised Bed

Wood, stones, bricks, and cement are the most common materials used when making raised beds. Wood is easy to find, to build with, and often is not that expensive. When building your beds with wood, you want to choose wood that will not rot easily. If you can, choose wood such as cedar or redwood, as both of these are more resistant to rot because of their natural oils. Stay away from pressure-treated wood or wood covered in creosote, as these products have heavy metals and poisons such as arsenic, copper, and chrome. These chemicals can leach into your garden soil and, ultimately, into your food.

If wood is not the look you want, rocks are often easy to find and can be very attractive. One disadvantage to using rock is that it does not offer the same barrier from weeds and grass as solid wood sides; however, using cement to fill in the crevices and cracks between the rocks will make for a more solid barrier.

If you want a more defined raised bed but do not want to use wood or stone, try using cement blocks, standard masonry bricks, or larger interlocking bricks. They come in various colors and sizes and can be easily stacked to increase the height of your raised bed if height is a concern. For a more involved and a permanent option, make your raised beds with cement.

This design is for a 4-foot-wide, 8-foot-long, 12-inch-high raised wooden bed. Here is your list of materials for one raised bed:

Most building supply stores will cut the pieces of wood for a minimal charge, saving you time. Following the earlier instructions, you should have two (8-foot by 2-foot by 12-inch) pieces and two (4-foot by 2-inch by 12-inch) boards to make your rectangular box; you should also have four (1-foot by 2-inch by 4-inch) pieces.

Assembling Your Raised Bed

Here are the steps to follow:

  1. Lay each 8-foot length of board on the ground. Place a piece of 1-foot long 2" × 4" board at each end. Stack the short board on top of the long board, aligning the 12" length of the short board with the 12" end of the long board. Using three screws on each, attach the 2" × 4" length to the long board. Drilling a guide hole slightly smaller in diameter and not quite the length of the screw into the wood first will make screwing the pieces together easier. Attaching the 2" × 4" to the long board will give the sides of your raised bed more support.
  2. These 8-foot boards will be used as the long sides of your rectangular box. The 4-foot lengths are the ends of your box. Align each 4-foot length to the 8-foot boards at ninety-degree-angles, and attach using three screws on each corner. You now have a four-sided raised bed.
  3. Proceed to spread the drain rock evenly within the rectangle, pick up the bed, and lay your wire bottom out flat on top of the layer of drain rock. If you are using chicken wire, it will tend to curl back into its rolled form as you struggle to spread it out. Have the wire overlap the outside dimension of the enclosure by two to three inches. Then lay the bed down on top of the wire. Using a heavier gauge rigid panel type of wire is easier to work with alone, as you can just lay the flat panels down. Make sure the holes are no larger than the ones in chicken wire, to keep out voles.
  4. If you prepare the raised bed in the fall, you can stack it with manure and mulch the top with spoiled hay to mellow through the winter. In the spring you can till in all the site-made compost; throughout the winter, the nutrients have been bathed with rainfall and composting in your bed. A garden fork is all you will need to work the bed, although some growers have tiny tillers.

The containers you decide to use will depend on your budget and your ingenuity; growers are continually finding new sources for earth-containing cannabis homes. There is no right way or wrong way, as long as you remember drainage is a key factor with containers.

Raised wooden garden bed.

Container Soil

A container-grown plant is far more dependent on you for food than a plant that grows in the ground. Even if they are fed on schedule, the ground-planted cannabis can seek out nutrients. The container plant has a much smaller and rigidly limited environment; they react much more quickly if you forget or delay a feeding.

Once your little seedlings are up, they are working hard at building healthy roots and making large green leaves for efficient photosynthesizing. Photosynthesis is the process your plants use to combine sunlight, water, and carbon dioxide to produce oxygen and sugar (energy). Your soil mix must provide enough food for the plants to work with.

The right soil mix is essential to produce large, green, and happy plants. Cannabis is a fast grower and big feeder. It is much more sensible to plan ahead and not wait until the plant is frantically signaling you that it needs food or that its drainage is poor.

If you are working with clones, put the plants in their final containers right away. If you are starting from seed and must deal with the sexual differentiation phase, you will not have the space, time, money, or inclination to put each little seedling into a big grow container. Until they declare male or female, you will be monitoring them in three- to five-gallon containers and feeding them frequently. If you are growing indoors, a three- to five-gallon container may be the largest your plants will get. Indoor growers have limited space and do not necessarily want the garden to outgrow its room.

Consider the Soil

The basic requirement for all cannabis is nutrient-rich, well-drained soil. If you are not a gardener already, you may want to start out using really good, bagged potting soil. Some gardeners mix their own because they have control over ingredients and amendments. And, of course, there is the question of cost. There are various kinds available at garden centers, but do not be swayed by price alone. A cheap mix will be heavy on the perlite (not that perlite is bad—in fact, it is very good for drainage—but it contains no nutrients at all).

It is also important to note that many potting mixes are made to support an average-size houseplant in a small pot. They are frequently manufactured entirely from wood and bark fiber, composts, and soil conditioners, with a light, fluffy texture. This texture requires the addition of sandy loam to make cannabis happy. Additionally, these mixes seldom contain enough nutrients to support healthy cannabis growth for more than a few months, if even that long.

Starter Mixes

A good starter mix is one-third sandy loam for drainage, one-third compost you have made, and one-third organic bagged soil. If your grow is small, or cost is no object, a mix of the FoxFarm Ocean Forest Potting Soil is really the way to go. If you plan to mix soil, sandy loam can be purchased in bulk at some garden centers and by the yard at rural feed and fuels.

You should screen all your soil through a compost screen; this will remove lumps and bits of wood or other compost components that have not broken down.

The discard materials can be thrown back on your compost pile or used for mulch around other garden plants. Once you have screened your components, the soil will be easy to mix. It is easiest to screen and mix by the wheelbarrow load; the wheelbarrow makes a convenient mixing bowl and you can make certain all components are blended before filling your containers. Wear gloves and a mask while you screen and mix, especially if the materials are dry enough to be dusty.

Money Smart

You can easily make a compost screener by using pieces of two-by-four board and some strong, metal screening. Make a square the size that will fit over a wheelbarrow and nail the screening to one side of the square. The wooden frame will make a lip to hold soil as you rub it through the screen into your wheelbarrow.

Water in the Soil

Once you have filled your containers with the carefully blended, screened soil mix, you need to gently water the soil and mix lightly to eliminate dry spots. Fill the container to standing water three times; note the water coming from the drain holes. This should ensure that the soil mix is evenly dampened.

Plant Your Seedlings

Prepare a hole slightly deeper than the pot the seedling currently sits in, scratch in a small handful of bone meal, unpot, and gently place the seedling in the hole. It is better to transplant when the seedling’s soil is slightly dry; soil that is wet can break apart and take some of the seedling’s root system with it. Fill in around the seedling and gently but firmly press it into the soil; this will make for good soil contact for the roots and helps the plant transition more easily. Water the seedling and gently press it in place one more time. Ideally, transplanting should be done in early morning or in the evening so seedlings are not shocked by the hot noontime sun.

Fertilizing

If you start out with pure high-end bagged soil or create a similar blend on your own, there is really no need to initially feed too much extra if the containers are large. A small handful of bone meal worked into the planting hole will start each young plant off with good root-building food, and the plant will draw what it needs from the soil.

A manure tea can be fed once a week after watering; manure teas are so gentle that some growers feed each time they water. If your plants have a healthy green foliage and are growing vigorously, they are getting what they need. Stay alert for narrowing of leaves or yellowing in color; the plants are signaling they need food. Bear in mind that indicas tend to have very dark green leaves, and sativas are a paler green, like healthy bamboo. Do not mistake a genetic trait for a plant problem. Plants that are hungry for nitrogen will pale; feed with manure tea and observe them. If you were correct, the plants should respond within three to four days.

Figure on using about a gallon of composted manure to four gallons of water to brew manure teas. Some kinds of manure are higher in nitrogen than others (bat guano is one of the highest), so you can adjust your blend slightly as you see how your plants respond.

If you use packaged fertilizers or ones you need to mix before applying, remember to use only organics, and know that more is not better. Read and follow instructions carefully to prevent burning your plants.

Watering

Remember, rooftops or decks can be much windier than gardens closer to the ground; wind dries out plants and soil, so these sites will require more and closer moisture monitoring. Also, plan ahead and bear in mind that large containers of soil can get extremely heavy when fully watered, either by you or by rain. Make certain your deck or rooftop can safely take the weight of your container garden.

The amount and how you water in container gardening will have a large effect on how well your cannabis plants grow. Cannabis likes to dry out a little bit between waterings—the soil should just be starting to pull away from the rim of the containers. Then you need to water slowly with a gentle stream from your hose. The goal is to have the water gradually permeate the soil mix all over, not to create channels of least resistance where water runs down and out.

Watering ten large cannabis plants in twenty-gallon containers can take a lot longer than you might think. An egg timer is a useful tool for watering; you can start the water going and come back to check at fifteen-minute intervals. The container should fill and drain down three times to ensure that the plant is watered thoroughly. Just damping the top surface of the soil may look good, but the lower part of the container soil will be dry as a bone, and leave your plants unhappy and thirsty.

Depending on weather conditions (extra hot, or windy, or rainy and cool), you will have to vary your watering schedule. Stick a finger into the soil near the plants’ roots. Is the soil damp from dew and extremely dry underneath? You need to know before the plants show stress.

During the phase of vegetative growth, it is fine for the outdoor grower to spray the plants’ leaves off after watering in the evening. This will knock off most unwanted insects and refresh the plants after a long, hot day. Do not overhead water cannabis as a general practice: The plants do not like or require it, and you risk burning the leaves if the sun is high and hot.

Keep It Simple

A moisture meter is an invaluable aid in checking how much water your plants need. These are readily available at your local garden supply, starting at under $5.

Container gardening of cannabis is a fun and relatively easy way to start out as a grower, and most indoor growers have to use containers. It is a good way to protect plants from bad soils and burrowing animals, and it is extremely productive if done correctly.