My friend Anne Marie loves to cook with fresh ingredients. But, with two small children, a job, and a musician husband with odd hours, there is not much time for food shopping. Even though she lives in an apartment in Brooklyn, New York, she grows a selection of her favorite ingredients right outside her kitchen window: baby lettuces, cilantro, arugula, and cherry tomatoes (Super 100's and yellow cherries are best for containers). As it is, the few hours of sunlight and a dash of garden ingenuity lets her round out their salads with the cucumber plants that grow up the kitchen window gate. There are actually many more vegetables and herbs that would thrive in this controlled environment.
Setting Up for Success
Vegetable plants are not snobs, they are just as happy to grow in a container as in a bucolic garden, and can share space with other plants. What they do need is some sun and a lightweight well-drained organic potting mix -- not garden soil, which is too dense and heavy for a container. When deciding what to plant, take into consideration the amount of sun your space gets, and choose accordingly. Before filling the pots with soil (leave an inch between soil and pot rim) I put a coffee filter or piece of mesh in the bottom of the pot so the soil will stay put, though not everyone thinks this is necessary. Consistent (probably daily) gentle watering is especially necessary when growing in pots, as the soil dries out quickly. The smaller the pot the faster this happens, and that is why I choose pots of a decent size. Plants will do better in a bigger pot (10" across and at least that deep is a good size, or 14" to 18" would be best). For bigger pots, consider putting them on coasters. Soil is heavy and you may want to move the pots to follow the sun.
I work a handful of organic compost into the soil before planting. Leave a little space between seedlings, make sure the roots are covered, and do not press down on the soil. If there is room between the seedlings, moisture can be held in with a bit of mulch. Mulch can be just about anything, gravel, pebbles, bits of slate, broken pottery chips, sea glass - spread it lightly please.
What to plant?
Start with lettuce seedlings or transplants, rather than seeds. It will give you quicker results and instant gratification. Then press a few nasturtium seeds into the soil around the edges. Graceville vines will drape over the side of the pot and the lovely blossoms are an edible and decorative flourish for salads. With guidance from your nursery person, choose a few varieties of compact microgreens such as loose leaf lettuces ('Red Sails' or 'Oakleaf' are favorites) to debut in your container garden. Lettuce is a cool weather crop, so plant early, leave a little space between seedlings (remember, seedlings are small), and lightly water often. When the leaves look to be the right size for harvesting, gently pinch the outside ones, leaving the others to continue to grow for repeat harvests. If you haven't grown and harvested...and eaten, your own lettuce, you are in for a treat! When you branch out after lettuce success, go for the dwarf or miniature cultivars of the vegetables you want to grow.
Another city dwelling friend with a small terrace on a high floor has bragging rights to fresh, organic salads from spring well into fall. The microclimate of her enclosed area extends her growing season. For more than one crop in a pot, she chooses a larger container that is at least 16" deep and a few stakes for the tomatoes and other plants. Vertical growing works just fine for many miniature vegetables: staked eggplants, string beans, peas, even peppers, cukes, and zucchini will yield a cornucopia of tasty food. And mixed growing is visually satisfying. Think edible and ornamental -- a border of red leaf mini-lettuce and Swiss chard at the base of a cherry tomato tower is a two way feast.
How to Retain Moisture
I am a lazy plant feeder -- okay, probably more forgetful than lazy -- though I do like the results and always promise myself to be more consistent. Liquid organic plant food certainly is good for both the health and productivity of your herbs and vegetables. Once again, consult your friendly nursery person, especially when combining plants with different needs in one pot. I believe in fish emulsion ever since I learned that Native Americans planted fish heads under the three sisters combination grew together and sustained them: corn, beans and squash. (Not everyone loves the fishy aroma). Liquid plant food can be applied pretty regularly, it washes through the soil due to the required constant watering.
My container vegetable garden is on a deck in a rural area so it is in a constant and often comical battle with squirrels, chipmunks, and occassionally deer. City gardeners have one distinct advantage, especially the high up ones where the not even the city squirrels go....there are no deer nibbling at their plants. Please let us know how your containers do -- it is wonderfully satisfying to grow some of your own food.