A friend recently asked me about growing vegetables on a deck. She had tried tomatoes last year, but didn’t have muck luck; the plants only grew to about 2 feet high and produced 1″ diameter tomatoes that never turned red. So what happened, and what are the basics of growing vegetables in containers? I will attempt to address the most basic principles of container gardening here. This is a fairly diverse topic and I highly recommend McGee & Stuckey’s The Bountiful Container for reading, but if you have additional questions that aren’t addressed in this article please post a question below or send me an email.

Before I delve into plant basics, I will address the obvious but often forgotten topic of the container. Perhaps you bought a starter plant from a local greenhouse that is already in a container, or you’re starting from seed. Seeds can be started directly in the container that will house the plant until harvest, but starter plants need to be transferred into a larger container so the roots have room to get big enough to feed the plant through production. Plastic pots, while they aren’t yet recyclable in the Philadelphia area, are the most simple and efficient type of pot; they retain moisture unlike clay (unglazed) and wood which have the tendency to dry out quickly, and they do not rust or oxidize like metal. With proper storage (bring them indoors in winter) they will last for many seasons. Even if you leave them outdoors in winter, they are fairly durable though more prone to becoming brittle and cracking over time. It is also extremely important to use a pot with drainage holes in the bottom (use a saucer underneath to catch excess water). If you are converting a found item into a pot, drill holes in the bottom. Whether the pot is new or old, it is very important to “sterilize” it before you use/re-use it - this is to get rid of any disease spores that could develop, and is easily done by scrubbing the pot with a 10% solution of bleach water (1 part bleach : 9 parts water). Rinse the pot with plain water after you have scrubbed with the solution, and allow it to thoroughly air dry before planting in it. Equally important to drainage and sterility is the size of the pot required for what you are planning to grow. While most of your vegetable (and flowering) plants will do just fine in an 8 to 10 inch pot, some plants like tomatoes need deeper soil (12 to 18 inches). If you’re buying seeds, this information is sometimes listed on the packet, but if not do some research online or talk to your local gardener where you buy plants or seeds from and they should be able to guide you based on what you are planting.

Next up is soil. Good soil is extremely important because it allows for quick drainage so the plant doesn’t get waterlogged, while simultaneously retaining moisture to nourish the plant. The easiest thing to do is go to your local garden center and buy a bag of potting soil formulated for vegetables. In Philadelphia, the best potting soil you can buy is Organic Mechanics which is locally produced in West Chester and available at Whole Foods for something like $2 a bag. However, this is generally only a seasonal item at WF and it seems to come around in early summer rather than early spring when a lot of the planting is going on in our region. This means you’re probably buying soil from Home Depot, Lowe’s, WalMart, or Target, and out of those options Miracle Grow Organic Choice Potting Mix is probably the best bet. However, I have to say that I do not trust that Miracle Grow is really “organic,” mainly because anything laying claims like “grows plants twice as big organically” formulated by a chemical company just seems a little unrealistic to me. But I have looked everywhere, and unless you can find Organic Mechanics at Whole Foods, want to mail-order soil, or make your own soil, Miracle-Grow is probably what you’ll end up with. If you’re able to mail-order, I recommend a company called Home Harvest. While unfortunately not local (they’re in Michigan), they carry quality supplies, including Foxfarm potting mix which I am testing out this season, for a price that I have not been able to match anywhere else on the internet. If you are willing to spend a little more time, you can make up your own potting mix using a variety of different materials, the most simplest being 2 parts compost (like earth worm castings) : 1 part perlite : 2 parts coir or sphagnum moss. See this resource from the National Sustainable Agriculture Information Service for additional do-it-yourself potting mix recipes. I am also experimenting with some home-made varieties this year, so I will post an entry at a later date on my findings and recommendations.

Now we will get to the plants. Plants were not originally made to be grown in containers. I say this because some vegetables simply do not fare well this way, and some plants have been hybridized to be happy in containers (like carrots). Other plants do not like to have their roots disturbed and so they should be started in a container that is large enough to house them as adults so you can grow them undisturbed rather than transplanting them (beans, peas, carrots, beets and radishes are among this group). Some plants are better to buy as transplants unless you have lots of patience and are familiar with all the seedling care and transplanting that must go on before they are really ready to “let go” and do their thing (these include tomatoes, peppers, eggplant, basil, chives, and other herbs). Additionally, some plants like tomatoes and cucumbers are susceptible to a variety of diseases, so select varieties that are both disease-resistant and are better suited to your growing region (humidity tolerant, drought tolerant, short season, etc.) to reduce climate stress. John Scheeper’s Kitchen Garden Seeds sends out a free catalog every year and is a great resource for learning about the disease-resistant varieties and climate tolerances of just about any “kitchen garden” plant.

Another important factor to consider are the lighting conditions your plants need (full sun, part shade, shade). These requirements should be listed on the seed packet or plant tag from your nursery. If not, be sure to ask your local gardener or look up this information online. Most vegetable plants require full sun, while herbs sometimes like part shade, as do heat-tolerant varieties of cooler crops. Plants that flower like tomatoes, peppers and cucumbers need a minimum of 6 hours of sunlight each day, while leafy plants like lettuce and spinach can suffice with 3 to 4 hours of sun. Another consideration that is related to light, especially if you’re gardening on a porch, patio or rooftop, is heat gain which can be damaging to the plant or the plant’s roots. Generally any concrete or black floor surface will absorb a lot of heat and radiate it back to the plants, and you may want to consider insulating your plant pots to reduce the amount of heat gain that may cause damage to the roots. Any wall surface that is white or very light will reflect light back to the plant. This is not always an issue, but if the soil seems to be drying out quickly or the leaves are getting dry, consider using shading devices to or planting climbing plants like beans, cucumbers, peas or nasturtium on a trellis that can grow to provide shade to some of the other plants if necessary.

Almost last, but very importantly: FERTILIZE. Plants need various nutrients at all life stages to keep them healthy and growing. Nitrogen nourishes plant leaves and foliage, phosphorus promotes blooming and nourishes flowers, and potassium promotes strong roots and overall health. Fertilizer packages usually have a number like “10-5-5” and that translates to “nitrogen-phosphorus-potassium.” Plants like lettuce need more nitrogen and plants like tomatoes and cucumbers need more phosphorus. Fertilizers are water-soluble, and you should always use the dilution rate that is listed on the package; never mix a stronger ratio as it can burn the plant. Generally, plants should be fed every 2-3 weeks, but this information should be listed on the fertilizer package and that is the ultimate rule of thumb. Plants also need additional nutrients to survive such as calcium, magnesium, sulfur, and iron, commonly found in items like greensand, dolomite lime, liquid seaweed, magnesium sulfate, and rock phosphate. Throughout time I have found that using a fish/seaweed fertilizer like Neptune’s Harvest yields the strongest, healthiest, most abundant plants. However, I have had a hard time finding that locally around here and it’s fairly expensive to ship, so I still rely on my mom to bring some down when she visits in the summer. Another product line that I really like is Espoma (Garden-tone and Tomato-tone). I can generally find their products locally at Lowe’s, Home Depot, Whole Foods, or smaller local nurseries, but they’re also fairly cheap to buy online at Home Harvest. Note that one bag will probably last you at least 3 seasons, depending on the size of your garden.

Select plants that make good “companions” to plant in the same container. This minimizes space and makes for some eye candy as well. Plant a taller plant that yields later in the season in the center or toward the back of a container and pair it with low-growing bushy plants that yield earlier in the summer or need less sun. In this way the plants share nutrients and light conditions. For example: pair lettuce, radishes, spinach or herbs like basil and parsley with tomatoes, peppers, or cucumbers. There are plenty of ideas on plant pairings in The Bountiful Container, but if you have experience with kitchen gardening I’m sure you can come up with some of your own combinations.

This should be enough to get you started and well on your way to understanding the important elements to grow your own successful container gardening. The Bountiful Container book I referenced is also available at the Free Library in case you want to take a look at it and see if it’s something you want to invest in. I have mine all tabbed up and refer to it constantly. It also has some really good recipe ideas! I also find this online forum particularly helpful: GardenWeb. As always, if you have any specific questions, feel free to ask away.