Author’s note: The following essay first appeared in THE NEW ENGLAND GARDENER’S YEAR by Reeser Manley and Marjorie Peronto ( 2013, Cadent Publishing, Thomaston, ME.) The title and text have been only slightly changed for this printing.
When the vegetable garden’s beds, as outlined on the coming season’s planting plan, are all spoken for, and you wish there was just a little more space for a pepper plant or two, or a small patch of that new lettuce variety, think pots. Vegetables in pots are a moveable feast. The pot that this year grows lettuce in a shady corner of the perennial bed was used last summer to grow basil on the sunny porch steps.
In this year’s vegetable garden I plan to grow eight different cucumber varieties, some with white skins, others yellow. There is not enough room in the garden’s beds for this trial, so I will grow each variety in its own three-gallon plastic pot, lining up the pots in front of a trellis.
Potted veggies can be a feast for the eyes as well as the table. We are not fond of eggplant’s texture or flavor, but in 2012 we grew the variety ‘Hansel” for its bright purple miniature fruits and lovely lavender flowers, both summer long features of this slender, “little finger”, eggplant. And who knows, perhaps we’ll learn to enjoy eating eggplants.
Almost any container will work, provided it has drainage holes in the bottom and suitable capacity. Use the following table to determine the size container needed for various vegetables.
Recommended Container Sizes for Vegetables
Vegetable Container Size Number of Plants
Broccoli 2 gallon 1 plant
Cucumber 3 gallon 1-2 plants
Eggplant 5 gallon 1 plant
Green Onions 1 gallon 3-5 plants
Leaf Lettuce 1 gallon 2 plants
Parsley 1 gallon 3 plants
Peppers 5 gallon 1-2 plants
Radish 1 gallon 3 plants
Spinach 1 gallon 2 plants
Summer Squash 5 gallon 1 plant
Tomato 5 gallon 1 plant
There was a time when container gardeners had to make their own growing media, mixing horticultural grade vermiculite, peat moss, perlite, and various mineral nutrients to produce a soilless mixture that would provide physical support for the plant yet drain well (garden soil drains poorly in containers). The only other options were packaged soil mixes that were generally too tight, held too much water, and thus drowned plant roots. Thank goodness those days are over!
These days there are some excellent soilless media for container vegetable production. I use either ProMix or one of the Fafard mixes, adding composted cow manure or worm compost as a nutrient source (one part compost or castings for every four parts soilless mix) and wetting the mixture thoroughly before seeding or transplanting.
I like to give all of my containerized veggies a shot of liquid fish emulsion once a month during the growing season, beginning a week or so after potting. My thinking is that the frequent watering necessary for container production rapidly leaches nitrogen out of the pot and it needs to be regularly replaced. I use half the recommended amount of the fish emulsion concentrate unless the plants tell me there is a definite nitrogen deficiency (yellowing foliage or no new growth) – too much nitrogen can delay flowering and fruiting.
Most importantly, avoid wetting the foliage of plants when watering since moisture on the leaves encourages plant diseases. When to water will depend on the container size, plant size, and weather conditions, so you should check each pot every day. Use your index finger to see if the soil is dry about an inch below the surface; if so, water the pot slowly, letting the water seep into the soil, until you see some water emerging from the drainage holes at the bottom of the pot. This will ensure thorough watering.
I put our pots on large rocks or other surfaces that will allow excellent drainage of excess water. The drainage holes of pots placed directly on the ground can become plugged with soil or roots that grow out of the container and into the surrounding soil. Elevated pots are also less likely to attract slugs which like to spend the day beneath objects resting on the ground.
Mulches can be placed on the surface of the container’s soil mix to reduce water loss. Keep in mind, however, that you may be providing another hiding spot for slugs.
Container gardening is a rapidly growing avocation and, for many urban gardeners, containers are the only option. Pots filled with vegetables, as well as flowering plants, are becoming a common site on the balconies and patios of apartment dwellers. Parents are discovering that container gardens are a great way to introduce children to the joys of gardening.