Cultivating Container Gardens

This chair holds a planter and a small birdhouse.

This basket filled with edible flowers and herbs lives in an old wagon.

Did You Know?

Limited by space or time? Try growing container gardens. All you need are containers, potting mix, fertilizer and plants.

Considering Creative Containers

Plants emerging from terra-cotta or plastic pots, windowboxes, or hanging baskets are common sights, and they make great growing vessels. But also try thinking outside the box. Practically any type of container can be used to grow plants as long as it holds soil, can drain water, and is large enough to accommodate the plants you're growing.

The larger the container, the larger the plant (or number of plants) you can grow to maturity. Take vessels for veggies. A half barrel planter can accommodate large tomatoes, squash, or eggplant, with room to spare for small crops such as carrots or lettuce. Five-gallon containers are fine for dwarf tomatoes, peppers, beans, and other vegetables and herbs. You can raise a mini salad or herb garden in an 18-inch (diameter) pot. Soil depth is also important. Deep-rooted plants like tomatoes need at least 12 inches of soil, but radishes can get by with as little as 4 inches. Windowboxes should be at least 9 inches deep.

Think about drainage and porosity when you choose containers. For plants to have healthy roots, soil needs to drain well. If a container lacks holes or other methods for drainage, water can build up and roots can smother. On the other hand, if a container dries out too quickly, plants can suffer. Because porous materials, such as unglazed terra-cotta and wood, dry out faster than materials like plastic, they have to be watered more often, but they have the advantage of keeping plants from getting waterlogged. (Large containers of either type retain moisture better than smaller ones.) The materials you choose may depend on your climate, the plants you're growing, and your willingness to water.

Choosing Plants and Schemes

What do you envision spilling out of your containers? Incredible edibles? Eye-appealing creations with complementary colors, textures, and forms? What about theme gardens such as the following?

a barrel full of salad with multiple colors of leaf lettuce, a bush cucumber, a dwarf patio tomato, and some herbs
a tomato sauce wheel barrow sporting a dwarf tomato plant in the center, herbs such as oregano and basil on the sides, and onions between the herbs
a scented hanging basket with nicotiana, heliotrope, lavender, and geraniums
a series of terra-cotta pots featuring an ethnic garden such as an Asian planting of greens, radishes, cucumbers, eggplants, and scallions

Preparing Pots and Pampering Plants

Drain it! Containers need to have some way to drain water away from plant roots. If a container doesn't already have drainage holes, and they would be easy to make, you can put in 1/2-inch holes at or near the bottom. If holes are at the bottom, make sure there's space underneath for the water to drain out. You might have to raise planting containers up on bricks or blocks. If you put holes in the side an inch or so from the bottom, extra water can remain in the reservoir. To keep from losing soil if holes are large, line your containers with newspaper or nylon mesh window screening, which will also prevent pests from entering. If your container has no drainage holes and it isn't practical to make them, you can place a smaller container with drainage holes inside the first one.

This red, white and blue planter celebrates the Fourth of July.

If you have a container that won't hold onto soil or water well, such as a woven basket or old boot with holey soles, you can line it with thick plastic, bubble pack (used for shipping), or a plastic milk jug or soda bottle, and punch drainage holes in the lining with a nail or pencil. Wire hanging baskets lined with sphagnum moss retain moisture, but also enable water to naturally drain.

Note: If you're using containers that have previously been used to grow plants or had unusual substances in them, clean them with an environmentally friendly disinfectant or soak them in a solution of 1 part bleach to 10 parts warm water before planting.

Provide mixed media. Your precious plants should thrive in a soil mix that drains well, retains moisture like a sponge, and offers support and nutrients. Garden soil is generally too heavy for container plants and may contain diseases or pests that could get out of hand. Your best bet is to buy a sterile potting or soilless mix or create your own. Here are a few recipes:

1/3 potting soil, 1/3 shredded peat moss, 1/3 perlite
1 part potting soil and 2 parts organic matter (compost or peat moss). For better drainage, you can add builder's sand or vermiculite.
16 quarts sphagnum moss, 16 quarts vermiculite, 7 oz. bone meal, 3 oz. blood meal, 3 oz. ground limestone (The last three ingredients contain important nutrients that potting soil and organic matter otherwise provide.)

Feed 'em and reap. Don't be misled by that phrase. Plants actually produce their own food through photosynthesis. However, you'll need to provide mineral nutrients via a water-soluble fertilizer every couple of weeks. Some gardeners prefer to fertilize with a dilute solution every other time they water. Others add a dry controlled-release fertilizer at planting time and supplement it with liquid after a month or so. Consider using organic fertilizers such as compost or compost tea, fish emulsion, or liquid seaweed.

Keep them moist and cool. Think moist, not soggy. Plants dry out much more quickly in containers than in the ground (and more quickly yet in porous containers). How often you have to water will depend on the nature and size of their containers, plant types and sizes, and wind and sun exposure. Don't be surprised if large container plants need daily watering. The rule of thumb is to water when the soil feels dry a couple of inches down. To wash away any buildup of fertilizer salts, always water thoroughly until it drains out the bottom.

In the heat of the summer, try some of these techniques to conserve moisture and keep the soil (and thus, the roots) cool:

Mulch container plants with compost, peat moss, or other organic materials.
Experiment with water-holding polymers (weird granules that get jello-like when wet), which hold a lot of moisture.
Group containers so plants shade one another's roots.
Keep roots cool by placing a container inside a larger one and fill the space in between with peat moss or shredded paper, or make cardboard collars around pots.

Here are some points to ponder as you plan:

Think small. When perusing seed racks, packets, and catalogs, have your young detectives identify words and phrases that fit the small-space bill: compact, bush (especially with squash varieties), for containers, tiny, dwarf, and so on.

Consider climate. Make sure to pay attention to planting dates based on your climate and frost-free period as you would with any outdoor garden. The benefit of containers is that you can move them in or under cover if frost or cold temperatures threaten (assuming they're not too heavy).

Select for sunlight. Choose plants according to the amount of sun available in your prospective container garden location. Most vegetable and herb plants you're likely to grow need at least six hours of sunlight each day. Leafy vegetables such as spinach, cabbage, and lettuce can tolerate a bit more shade; flowers vary. Check catalogs, seed packets, for sunlight requirements.

Consider companions. Plan to put plants with similar needs (e.g., sun, shade, water, or fertilizer) in a given container. You might also grow deep-rooted plants with shallow-rooted ones because the combination will make better use of nutrients and water.

Think about going vertical! Consider creating garden vessels for vining plants such as pole beans, cucumbers, gourds, morning glory, clematis, sweet potato vine, star jasmine, or passion flower.

Delve into design. If you want to introduce an artistic dimension to your container project, have kids think about the shapes, textures, and colors of potential container plants and flowers. Do they envision a riot of color or soft, calming hues? Some plants, like snapdragons are tall and spiky; others, like impatiens, form round mounds; and plants like lobelia are long and trailing. Coleus have striking foliage.

Courtesy the National Gardening Association's Kids Gardening Web site.

"When you garden, you grow" is trademark of the National Gardening Association. For more ideas and inspiration on gardening with children, visit NGA's Kids Gardening Web site.