6

planting in containers

Assembling the necessary equipment for container gardening can be simple and affordable if you repurpose certain types of food packaging. Clear plastic containers that hold berries, for example, work beautifully in microgreen gardening, but there are other options, including a few described in this chapter.

epurposed containers are ideal for microgreen gardening because they’re lightweight, versatile, and fit easily on most windowsills. The alternative to using repurposed food containers is to use trays (see chapter 7). The advantage of using trays is that you’re able to grow more microgreens at once, but this efficiency comes with certain challenges. For one, trays can be cumbersome. It’s easy to spill soil or drip water from a tray, for example. In addition, trays seldom fit on windowsills, which is a disadvantage if you don’t have a large surface in front of a window.

As discussed in chapter 3, microgreens that are grown in containers are watered from the bottom. This involves putting containers that have holes in the bottom into shallow pools of water so that the water is absorbed directly into the soil from below. This watering method is the key to growing mold-free microgreens, and it’s a topic that’s explored further in this chapter. Microgreens that are grown in trays can’t be watered from the bottom, although side watering is an option that can deter mold growth (see chapter 7).

One point worth noting here is that small containers have the advantage of providing somewhat more surface area because plants can lean outward and spread beyond the containers’ perimeters, allowing you to fit in more seeds. In contrast, trays have tall lips and broad surface areas that don’t allow expansion beyond their borders.

THE BEST CONTAINERS TO REPURPOSE

he containers that house fresh fruits are ideal for growing microgreens. Other common receptacles, such as those that are packed with hummus, tofu, or yogurt, are also good choices. As an alternative, you always have the option of purchasing plastic seedling pots from a garden supply store.

FRESH FRUIT CONTAINERS. Rather than immediately recycle the clear plastic containers in which you buy fresh fruits, wash and collect them. Stock up on empty pint (one-half kilo) and half-pint (one-quarter kilo) containers. Pint containers typically house blueberries, cherry tomatoes, and figs. Blackberries and raspberries come packaged in half-pint containers, which are half the depth but usually the same width and length as pints, making them particularly useful. Quart (one kilo) containers, such as those that hold strawberries, aren’t a good choice for microgreen gardening, however, as they hold more soil than is necessary.

While either pint or half-pint containers will work no matter which seeds you plant, some seedlings do better in pint containers, which are twice as deep. In particular, pea and root crops, such as beet and radish, grow best in pint containers. For most other crops, and especially for shallow-rooted seedlings such as basil and lettuce, half-pint containers are preferred because they can be filled with half the amount of soil as pint containers. Keep in mind, though, that microgreens in half-pint containers must be watered more frequently. In comparison, microgreens in pint containers need to be watered less often because they’re growing in twice the amount of soil.

Container depth matters because harvesting is easier when the container is filled with soil. When the soil line is even with the top of the container, you can efficiently snip the greens at the bottom of the stems, which would be hard to reach if the soil line were lower.

Plastic fruit containers have several features that make them ideal for container gardening. For one, they’re rectangular, which makes it easy to line them up on a windowsill, shelf, or tray. For another, they’re transparent, so they don’t obstruct your view of the growing rootlets inside.

Finally, they already have vents cut into their bottoms, which means the holes that are needed for bottom watering are already there. The vents, while convenient, present a slight drawback because the containers may splinter or crack along the vents after multiple uses. That’s why it’s a good idea to evaluate the condition of the containers after each harvest and recycle those that are worn out.

Pint and half-pint fruit containers are made of polyethylene terephthalate, the type of plastic (recycling number 1) that’s also commonly used to make water and beverage bottles. When containers made of this material are exposed to heat or stored for prolonged periods, the phthalates can migrate into the containers’ liquid contents. That’s why you can detect the taste of plastic in bottled water, including bottled spring water, especially if it’s transported from afar. At moderate room temperatures and for short durations, however, this type of plastic doesn’t affect liquid or solid contents.

HUMMUS, TOFU, AND YOGURT CONTAINERS. These receptacles are especially suitable for repurposing. You can modify them for microgreen gardening by punching holes in their bottoms. One slight disadvantage of hummus or yogurt containers is their shape, which is usually round rather than square or rectangular, like tofu containers. Round containers have less surface area for growing than comparably sized square containers, and fewer round containers fit into the same space as square or rectangular containers.

Hummus, tofu, and yogurt are typically packaged in safer plastics (recycling numbers 2 and 5) that transmit no chemical residue to food contents. People who are particular about the plastic they use may prefer these containers to plastic fruit containers for this reason.

FLOWERPOTS AND SEEDLING POTS. Suitable nonfood containers include flowerpots and seedling pots. Plastic flowerpots work best, since terra-cotta pots are heavy, bulky, and fragile. Seedling pots are pint-sized plastic containers manufactured specifically for growing seedlings. Like plastic fruit containers, seedling pots are made of polyethylene (recycling number 1). They’re inexpensive and can be purchased at well-stocked garden supply stores. Many commercial microgreen farmers use seedling pots.

PREPARING CONTAINERS

ou’ll need to make a few easy alterations to your containers so they’ll be suitable for microgreen gardening.

REMOVE LIDS. Since the lids of plastic fruit containers are joined to the bottoms on one side, you’ll need to cut the lids off of these containers. Because plastic dulls blades, designate an old pair of scissors for this task; don’t use the same pair you use to harvest microgreens. You may find it easier to trim off the lid if you turn the container upside down. After removing the lid, trim away any ragged edges. Set aside some of the lids for use during the early stage of germination of certain microgreens (see “Cover Up,” page 41).

PUNCH HOLES. While plastic fruit containers are already vented and don’t require this step, you’ll need to punch holes in other food containers, such as those from hummus, tofu, and yogurt, and possibly even plastic flowerpots. To make the holes, turn the container upside down. Use a pointed knife or pick to create holes in the plastic. If the plastic is too dense, make the holes by tapping a sharp nail with a hammer to drive it through the plastic. To facilitate rapid watering and draining, punch numerous holes in every container.

NEST AND REINFORCE. Pair up identical containers and nest one inside the other. This is an important step. Doubling up the containers adds rigidity, strength, and stability so that fragile rootlets don’t get jostled when you move the containers during watering or another step. Plus, by nesting one container inside of another, you create a buffer zone that protects the rootlets in the inner container from being crushed, prevents water from pooling in the soil, and provides ventilation (which prevents mold).

Basil, from day 1 to day 6.

LINE WITH PAPER. Line the bottom of the inside container with a piece of thin white paper, such as printer paper, before adding soil. To cut the paper to the correct size, place the container top-side down on a sheet of paper (or on a piece of cardboard if you want to make a reusable template), trace around the container with a pen or pencil to mark its outline on the paper, and cut a bit outside the outline with scissors. Then, starting from each of the four corners, snip a short incision diagonally toward the center. Firmly insert the paper into the bottom of the container, allowing the paper to come slightly up the sides; make sure the insert fits snugly.

Lining the top container with paper has a twofold purpose. While the primary goal is to prevent soil from draining into the water during bottom watering, the paper also prevents rootlets from entangling themselves in container vents and holes. This will make it easier to clean and reuse your containers.

GROW YOUR GARDEN

ow that the containers are lid-free, have adequate holes in the bottom, and are nested together for stability, it’s time to make a garden out of them by adding soil and seeds. For most crops, the simple sowing directions that follow will cover all you need to know. However, if you’re growing sunflower, pea, or wheatgrass, refer to chapter 8, which provides more specific instructions for successfully growing those microgreens.

FILL THE CONTAINER WITH SOIL. Scoop moistened soil (see chapter 3, page 17) into the container. Don’t pack down the soil, but do fill it right up to the rim. Filling the container to the top is important because it’s much easier to harvest the microgreens when the soil line is even with the container’s rim.

MEASURE THE SEEDS. Here is a cheat sheet that can help you determine the amount of seeds to sow in a pint or half-pint container. This step is optional if you’re using seeds that don’t require soaking, but it’s helpful to keep a record of how many seeds to use per container. The lengths and widths of pint and half-pint containers vary only slightly among manufacturers, so their total surface areas average about eighteen square inches (116 square centimeters). Here are the maximum amounts of seeds you’ll need per pint or half-pint container:

• tiny seeds (such as basil)	=	maximum ½ teaspoon (2.5 milliliters)
• medium seeds (such as broccoli)	=	maximum 1 teaspoon (5 milliliters)
• large seeds (such as radish)	=	maximum 1½ teaspoons (7.5 milliliters)
• extra-large seeds (such as beet)	=	maximum 2 teaspoons (10 milliliters)

Broccoli, from day 1 to day 6.

SOW THE SEEDS. Lay the seeds evenly and thinly upon the soil. Deep-bowled measuring spoons are excellent tools not just for measuring seeds, but also for sowing them: hold the spoon with your thumb and middle finger and gently tap the handle with your forefinger to sow the seed.

Only seeds that have been soaked should be covered with soil (see sidebar, “To Soak or Not to Soak,” page 10, for a list of seeds that require soaking). For all except soaked seeds, use your fingers to gently press the seeds into the soil, ensuring contact but not covering the seeds with soil. This will prevent succulent leaves from being encrusted with soil as the seedlings emerge and grow.

LABEL THE CONTAINER. Write the seed’s name on a label and affix it to the container (small labels the size of address labels work perfectly). Also inscribe the date that the seeds were sown; this notation will help you track the number of days you prefer to grow each variety of microgreen.

COVER UP. Until the seeds germinate, cover the soil and seeds with cloth (see chapter 3, pages 19 to 20) or even a bit of wet paper towel. If you’re growing one of the few seeds that require light to fully germinate, don’t use cloth or paper; instead, use the lid from the food container. Fruit container tops are already vented, but if you’re using other kinds of food containers, punch some holes in them. It’s not necessary to snap on the lid; simply place it atop the container. You might prefer to dispense with cloth covers altogether and instead cover only with lids. If you would rather not cover the containers even with lids, the seeds can be left uncovered as long as you mist or spray them three times daily.

WATER FROM THE BOTTOM

he technique of watering plants from below is adapted from a method used by large-scale microgreen farmers, who deliver their uncut crops to restaurants and markets still in their seedling containers. The microgreens continue to grow in the restaurant and the marketplace—and they do so without becoming moldy. Avoiding mold is the main goal of bottom watering. Water your microgreens whenever the top of the soil feels dry, usually once daily for half-pint containers and every other day for pint containers, which are deeper.

PREPARE A SHALLOW POOL OF WATER. Pour room-temperature water into a bowl, basin, or small tub until the water is about half as deep as the container of microgreens you’ll be watering. Don’t use cold water because it will chill the roots and delay their growth.

PLACE THE CONTAINER INTO THE WATER. The numerous vent holes in the bottom of the container allow for soaking now and for draining later. Let the soil soak up water for one minute or less, until the surface of the soil feels thoroughly moistened. Then remove the container from the water.

DRAIN THE EXCESS WATER. Allow the container to drain for one minute or more by setting it at a slight angle inside the sink or dish rack.

REPLENISH THE WATER AS NEEDED. If you’re watering more than four containers of microgreens, you’ll need to add water to the pool as it’s soaked up. Watering containers one at a time takes longer than watering four simultaneously in a large basin, which is a practical approach if you grow a lot of microgreens. A clean dishpan works well for most people, but enthusiastic growers who like to reuse all kinds of containers might be interested to learn that a repurposed drawer from an old refrigerator can hold six containers at a time.

DISCARD LEFTOVER WATER. If you didn’t line the container with paper as directed earlier in this chapter (see page 39), some soil may remain behind in the watering basin when you’re finished. This is especially likely to occur early in the growing cycle, before rootlets emerge. If you pour heavily soiled water down the sink, over time, the soil might clog the drain. One solution is to pour the water into the sink through a sprout-jar lid with a fine mesh screen, which will catch the soil. Alternatively, the soil and water can be discarded outdoors.

HARVESTING FROM CONTAINERS

hapter 5 includes general information about harvesting microgreens. Here are some additional details that pertain to harvesting greens grown in containers.

HARVEST BUT DON’T WASH. Small containers allow for an easy and efficient harvest. Since the harvest per container is likely to be small, you’ll probably want to trim away all of the greens at once. To do so, hold the container over a dish, tilt the container on its side, snip the stems with scissors, and the cuttings will fall into the dish. You need not even touch the microgreens, so they should be quite clean. In addition, because they’ve been watered from the bottom, the microgreens should be devoid of soil, and they shouldn’t need to be washed.

refrigerate the whole operation

If you grow microgreens in repurposed containers, you have the unique option of refrigerating the microgreens before harvest. If your greens are at their sweet peak but you’re not yet ready to eat them, simply put the container—soil and all—in the refrigerator. Because the cold air will dry out the plants, first put the container in a plastic bag, which you can leave open or tie loosely closed. For good measure, give the plants a little extra carbon dioxide by exhaling into the bag before tying it closed. The carbon dioxide will help to preserve the greens. If stored for one week with the bag open, the soil will dry out, so replenish moisture by bottom watering. You then can store it in the fridge for one more week. When you’re nearly ready to eat the greens, remove the container from the refrigerator and put it on the windowsill. Let the container sit for twelve hours before trimming so the microgreens reach room temperature.

HARVEST IN PATCHES. If you prefer to harvest only some of the greens growing in the container, trim them by patches or rows, leaving spaces into which the remaining greens can lean as they continue to grow. This harvesting technique is commonly used in tray gardening.

CUT LOW DOWN THE STEMS. What if you didn’t follow the earlier advice to fill the soil to the top of the container? This may or may not be a problem, depending on how far down the stem you prefer to cut. If you want to harvest as much stem as possible, but you didn’t fill the container to the rim, the stems are now deep inside the container and difficult to reach with scissors. But there’s a simple solution, especially if you’ve used softer, more flexible containers, such as fruit or tofu containers. Simply remove the inner container from the outer protective container. With one hand, loosely hold the microgreen container by its sides, and with your other hand, push up the bottom of the container. The matted clump of soil will slide up. When the surface of the soil is even with the edge of the container, snip the stems close to the soil line.

DISCARD THE SOIL. After a full harvest, hold the container upside down. Give the bottom a slight nudge, and the cluster of root-entangled soil will slide out as a single mass. If loose soil remains in the container, that’s a sign that you may have used more soil than necessary. For example, if you used a pint container, the next time you grow the same variety of microgreen, use a half-pint container instead.

Some rootlets may cling to the bottom of the container, especially if they’re tangled in the vents. To dislodge these, scrub and wash the container. If absolutely necessary, immerse the container in a sink filled with water to soak and loosen the roots.

the inside scoop: container gardening

• Repurpose food containers such as pint or half-pint containers that hold fruit or other containers that hold hummus, tofu, or yogurt.

• Use flowerpots or seedling pots for container gardening if you prefer or if you don’t have enough empty food containers to reuse.

• Prepare containers by removing lids, punching holes in the bottoms, nesting one container inside another, and lining the bottom of the inside container with paper.

• When it’s time to plant, fill the container to the rim with moist soil, sow the appropriate amount of seeds for the size of the container, and lay the seeds evenly and thinly upon the soil. (Don’t cover the seeds with soil unless they have been soaked.)

• Label each container with the name of the seed and the planting date.

• After germination, water the microgreens only from the bottom.

• Harvest the microgreens by clipping the stems close to the soil. Don’t wash the clippings.

• Put unharvested microgreens in a bag, container and all, and store in the refrigerator until you’re ready to eat them. (Allow them to come to room temperature for twelve hours before harvesting.)

Green Cabbage and Chinese Cabbage