Containers are the city gardener's very best friend. With pots, planters and window boxes made of terra cotta, wood, plastic or metal small space gardeners can fill their outdoor surroundings with vegetables, herbs and flowers and even trees, fruits and shrubs.

Almost anything you can grow in the ground you can grow in a container, as long as the container is large enough to hold the roots firmly in place. Terraces, plazas and roof top gardens throughout the area sport trees greater than twenty feet tall growing in containers. But even if you have room for only one small widow box, you can make that your garden and make it grow with perennials, annuals and trailing vines that can give you pretty flowers and edible herbs from early spring till late in the fall.

Now is the time to buy your pots, soil and plants to make your container garden come alive. The cold weather is over and it is time to move outside. According to the National Gardening Association, container gardening is the fastest growing segment of the lawn and garden industry. A plethora of pots and boxes in all types of sizes, materials and prices are pouring into the market at garden centers, in catalogues and over the Internet.

Prices range from a few dollars for terra cotta or earth-tone plastic pots to hundreds of dollars for stone or concrete urns in classic shapes. There are self-watering containers and whole container gardening kits complete with soil and plants that can be bought for as little as $12 and as much as $130.

Choosing the Right Container

Size is your first consideration. The pot needs to be large enough to hold the plant when it is fully grown. A tomato plant seedling might look good in a one pint pot, but when it is fully grown, that plant needs to be in a two gallon pot.

Plants need drainage so make sure your pots have holes in the bottom so excess water can drain out. If there is a hole-less container you just must have, you can always drill holes in the bottom to create drainage.

Terra Cotta is beautiful and old-fashioned but it is also heavier and more prone to breakage. Moisture evaporates faster out of clay pots meaning you might have to water a little bit more often.

Plastic pots have taken on a whole new look in recent years. They've been redesigned to look just like terra cotta. They are lighter weight, hold water better and don't break as often.

Wood is a durable material for planters and window boxes, especially if you buy rot resistant cedar or redwood containers. Avoid treated wood that contains creosote or penta that may give off plant harming vapors. Ordinary wood lined with heavy plastic sheeting does a fine job.

Metal containers, especially those made from galvanized steel, make excellent containers. Be sure to drill holes in the bottom for drainage

Soil Mix and Fertilizer

Ordinary garden soil or top soil is too heavy for containers. It also gets compacted over the season making it more difficult for the roots of your plants to spread out and flourish. Instead, plant your flora in a light weight, soil-based potting mix that contains the likes of sandy loam, peat and sand. This readily available product gives your plants the right balance of drainage, organic matter and stability your plants need.

Your container plants are very dependent upon you for food. Some soil-based mixes have fertilizer already mixed in. But you can do the same by mixing a granular, slow-release organic into the soil before you plant. This dose will feed your plants for 8 to 10 weeks. After that, you may need to add a liquid fertilizer such as fish emulsion as a supplement.

Watering and Care

During the heat of the summer you may need to water your containers as often as once a day. There are several self-watering containers on the market with built in reservoir that will cut your watering duties down to once a week. Water slowly and gently until small amounts of water drain out the bottom. I place saucers under most of my potted plants that hold water the plants call on later in the day and to keep the porch cleaner and dryer.

Mulching your container gardens is both beneficial and decorative. Spread a thin layer of shredded bark or other favored mulch to help keep the soil cooler and hold in moisture.

You don't want your container plants to be constantly buffeted by wind. Build a windbreak or fence along your terrace or roof top to cut down on too much damaging wind.

All of the annuals and most of the perennials you grow in your containers will not survive the winter. Simply plan to replace them each year. Most trees and shrubs will survive if you can move them to a more protected part of your outdoor space. You can also wrap them the containers in burlap or bubble wrap to help protect the root system from extreme winter cold. Do keep the plants occasionally watered over the winter if they don't receive any rain or snow.

Never use the same soil twice. Soil borne diseases like mildew can be passed from plant to pot. Each year empty the pots and wash them out with a chlorine and water solution to kill diseases. Add a little fresh soil mix to your permanent pots of trees and shrubs each year to replenish the soil.

Good Plants for Containers

The range of plants you can grow in your container garden is limited only by your imagination and by sunlight. If you have a shady spot, you should rule out tomatoes, marigolds, roses and other sun-loving plants that need 8 to 10 hours of sunlight each day to produce flowers and food. But there are plenty of plants to choose from and one of the beauties of containers is that you can move them around, even during the day, to take advantage of what sunlight you do receive.

Basil, rosemary, thyme, parsley, chives, savory and other herbs are some of the best plants you can grow in containers. In their native habitat, most herbs grow in rather difficult conditions to begin with. Plant them in individual pots or in one big one and snip off what you like to add to your favorite recipe.

Tuberous begonia, impatiens and coleus are three shade loving colorful annuals that I frequently grow in my window boxes in deep shade. Viola is another colorful annual I use in dappled shade window boxes in early spring.

Heuchera 'Palace Purple' and H. sanguinea 'Coral Bells' are perennials with richly colored foliage and delicate flowers that both grow well in containers in full sun to partial shade. Bells Foliage is another good choice for containers.

Even though you can grow plants of almost any size in containers, plants of smaller size are better best because they have smaller root systems. Smaller plants fit into containers more comfortably that larger plants.

Regular and scented geraniums, nasturtiums, marigolds, snap dragon, wax begonia, lobelia, petunia, low-growing dahlia, salvia and swan river daisies are good selections that will fill your planter with flowers in bloom in full sun for most of the summer.

Resources

Gardener's Supply, 128 Intervale Rd., Burlington, VT 05401, 1-800-863-1700, is an organically oriented garden catalogue that offers a good selection of containers, including the self-watering ones, as well as soil mixes and fertilizer. Also on the Web at www.gardeners.com.

www.windowbox.com has an outstanding selection of window boxes made of redwood, birch bark, twig, copper, iron, cedar, metal and other materials. They also offer several self-watering container garden kits called Urbox specifically designed for urban gardeners that come complete with pot, soil and plants. Phone number 1-888-GARDEN2

Garden centers will carry the Campania line of containers in cast stone, terra cotta and some of the best looking plastic pots I've ever seen. They have a new collection of cast stone containers based on the style of Gustav Stickley and other American designers of the early 20^th century. www.companiainternational.com or 215-538-1106.

Books

Paradise Found: Gardening in Unlikely Places, Rebecca Cole, Clarkson Potter, 2000, $35. Artists and urban horticulturist Rebecca Cole's book will inspire you to think creatively about what can possibly be grown in containers.

Containers: American Horticultural Society Practical Guide, Peter Robinson, DK Publishing, 1999, $8.95. A very practical little guidebook that gives quick tips, great how-to photographs and plenty of advice.

Container Gardening Through the Year, Malcolm Hillier, DK Publishing, 1995, $24.95. 160 pages of color photographs or interesting and unusual container garden planting combinations for spring, summer, fall and even winter.

Windowbox Gardening, David Joyce, Globe Pequot Press, 1993, $24.95. Written and photographed in Britain, this informative book will show you how yo can turn your terrace or patio into a containerized English cottage garden.