Vegetable Container Gardening
Learn the best plants and techniques for growing vegetables in pots
The following is my advice on growing vegetables in containers for outdoor use. Be advised that techniques can differ based on your geographical location, the type of plants being grown and whether they are indoor or outdoor containers.
Choosing your Container
Choose larger containers whenever possible so you don't have to water them as often. The only exception would be for shallow rooted plants like lettuce or spinach. You can grow them easily in a shallow container to save space and to save soil. I try and stay away from unsealed clay pots as they absorb a lot of water. I still love the look of clay though, so you can soak them overnight in water before use and that will help retain moisture. You can also seal the outside of new clay pots with a specially formulated clay pot sealer or by brushing on clear polyurethane. Painting the pots with acrylic paints will also help to seal the pots, though you will want to seal the paint also to preserve your paint job. Herbs prefer to be on the dry side, so if you have clay pots you would like to use, consider reserving them for herbs.
Containers come in a variety of materials, shapes and sizes such as clay, plastic, concrete, ceramic, wood and resin. I prefer plastic and resin as they are lightweight, relatively inexpensive, last for many years and come in hundreds of shapes, sizes, colors and designs. Whatever you choose, make sure there are adequate drainage holes. Many resin containers do not have holes drilled in them so you can use them for other things, such as a water garden. They are very easy to drill, however, with a standard ¼" - ½" drill bit. They also sell containers that are self watering which can come in handy on hot days or while on vacation.
When using especially large pots, take into consideration what they will weigh when full and if they will need to be moved once you set them in place. If there is any chance you will have to move them, I'd suggest putting them on a plant dolly before filling the container with soil and plants. Plant dollies are usually flat and made of weather resistant wood or metal and have four caster wheels on them. They come in different sizes depending on your pot and are usually not visible when under the container. Make sure the weight rating on the dolly can handle the weight of the container when full of soil, plants and water.
Remember that most anything that can hold soil can be used as a container for plants, providing it has proper drainage holes, so use your imagination and have fun with it. Wooden boxes, 5-gallon buckets, totes, and pails all make good containers.
Choosing Your Growing Medium
Soil for containers should be lightweight and airy to allow the roots of your plants to get the oxygen and moisture they need to be healthy. Soil from your garden is too heavy and should not be used.
I tend to buy prepackaged organic potting soil in large bags at my local garden center or discount store because it's easier for me, though I know many people who like to mix their own potting soil. I like to add 1 part compost and 1 part composted manure to 4 parts potting soil to my containers as I feel it helps to retain moisture better than potting soil alone without smothering the roots. The compost and manure also add important nutrients and organisms to the soil that plants need to survive.
If you want to make your own potting soil, I suggest 1 part compost, 1 part peat moss, 1 part course sand, 1 part perlite or vermiculite and enough bone meal, blood meal or another organic fertilizer, following the package instructions for the amount of soil mix you are making. If you don't have perlite or vermiculite, substitute peat moss in it's place. Leaf Mold is also a good addition to any soil mix. 1 part leaf mold added to the above ingredients is fine. You don't have to be exact with the measurements and you may need to adjust the mix based on the types of vegetables or herbs you are growing. I have a whole page dedicated to making your own soil mixes and fertilizers that you can check out here.
There are many vegetables suitable for growing in containers. In fact, there are many varieties that will grow smaller or varieties that are especially suited for container gardening or "patio" gardening. They will usually have this information on the seed packet. Cucumbers and pole beans get to be a little tricky to grow in containers because they like to vine so much, but they can be trellised and some come in a bush variety so they take up less space.
Keep in mind your container size when choosing vegetables. Lettuce, spinach, green onions, parsley and most herbs only need 6"-12" of soil to grow well. Tomatoes and Cucumbers grow better in a 5-gallon bucket and most everything else grows well in sizes in between.