Containers blossom out all over

The ''container revolution'' has blossomed onto doorsteps, balconies, patios, decks, and other small spaces. Even if you live in the center city - high-rise, townhouse, trailer house, or single house - the wearing of these small gardens can add food and flower to your life style.

If you are country-homed with space galore, containers let you plant those barren spots where nothing grew before.

Whether your style is elegant simplicity, exuberant informality, or rustic, there's container planting to match.

Two major things have contributed to the evolution of container gardening. For one, the past 15 years have seen the development and adoption of special soil mixes adapted for container growing. Second, many vegetables and flowers have been bred specifically for high yield in small spaces.

Soil mixes based on peat and other components were developed by universities and spread through the ranks of commercial greenhouse producers. Now they bring their benefits directly to the home gardener.

These soil mixes such as Jiffy Mix from Carefree Garden Products, which is made from sphagnum peat moss and vermiculite blended with special nutrients, provide an ideal combination of moisture-holding capacity and the necessary aeration to let the roots breathe.

This ideal growing environment helps plants pop off to a fast start and keeps them growing vigorously all summer, given timely additions of water and fertilizer.

Take the soil-mix idea one step further and use the bag and mix as a self-contained planter. The 16-quart size of Jiffy Mix makes an ideal pillow-pack planter that is portable, plantable, and practical.

There ar three sizes of Jiffy Mix: one containing 4 quarts of mix, one holding 8 quarts, and the third with 16 quarts.

The gallon size will easily grow two pepper plants or one tomato or a small bouquet of flowering plants. The largest (4-gallon) size is big enough for a modest self-contained garden.

After you get the bag of Jiffy Mix home, make a hole large enough to insert a hose and water slowly but thoroughly. Fill the bag with water until it resembles a balloon. Let it sit until the water thoroughly permeates the soil mix. Check to make sure that all soil pockets are moistened before you start planting. If not, water again.

When the mix is saturated, punch one hole in each side of the bag about halfway up the side. This serves for drainage.

Planting is very easy. Punch a number of holes in the bag equal to the number of plants. Plant growth is vigorous, but if you want full coverage fast, plant closer together. The dimensions of the 16-quart bag of Jiffy Mix are 13 by 20 inches. For instant coverage of flowering plants, space them on 3-by-4-inch centers. For slower coverage, space plants up to 6 inches on center.

Geraniums will grow vigorously. Compact marigolds, such as Bonanza Yellow, will remain modest in size. Be sure to plant near the edges so the foliage hides the edges of the bag quickly.

''Patio packs'' are portable. They can drape on decks for parties, call out flowery greetings to front-door visitors, or even serve as lavish centerpieces for a large indoor or outdoor buffet table.

Fully grown out and well-watered, the largest-size planted bag of Jiffy Mix weighs less than 35 pounds.

Care is easy, but frequent thorough watering is required so the plants don't dry out. Also add fertilizer. A balanced slow-release kind, such as 10-10-10 applied at planting time, is easiest.

After planting, water well. Then water as needed, making sure you don't let the planting dry out completely.

At season's end the soil mix is still reusable in other containers or for improving the tilth of a regular garden plot or flower bed.

A salad garden of lettuce, onions, radishes, and other small-space vegetables is an ideal container subject. Then, too, because they are harvested for leaves or roots, they will produce adequately, if not abundantly, in less than full sun.

Try Gold Rush zucchini, an All-America Selections medalist. Cucumbers, such as Pot Luck; and watermelons, such as new Garden Baby, have been bred for good production from bush or restricted vine. Voila, good container vegetables!

Peppers and eggplants make naturally attractive, compact plants. Good ones include Gypsy, another All-America winner, and Better Belle, a new, blocky, four-lobed variety that is great for nibbles or for stuffing.

Dusky is a choice eggplant with silvery-green foliage whose large yellow-eyed lavender flowers are followed by blackish-purple fruits of high sheen.

Determinate or bush-type tomatoes work best in bags of soil mix because they grow a modest set of foliage, then bloom and set fruit at the same time. Several varieties could include Patio, a long-time favorite; new President, a variety with good-sized fruit; and new Florida Basket, which cascades nicely to form an attractive plant loaded with fruit.

Explorer Potato, the first potato from true seed for home gardeners, not only grows well in soil mixes but forms lush green vines topped with flowers of light-lavender centered with yellow eyes.

New this year is SweetHeart Strawberry, which takes to container growing like ducks to water. The first strawberry from seed with good-sized berries, it's an everbearer that will produce next summer from a winter seed sowing.

Flowers also grow exuberantly when planted this way, whether the planting is a single variety or a mixed bouquet of complementing or contrasting flower colors, foliage textures, sizes, and shapes.

You might want to mix geraniums, such as the Smash Hits, planted down the center, with lobelia edged on both ends and the sides. Petunias, such as the favorite Cascades, combine well with more upright plants, such as salvia. For shade, impatiens is an ideal plant with many flowers of varied hues.

Another breakthrough this year are the first double impatiens from seed. Rosette is composed of solid colors while Duet is a mix with flowers gaily marked with white. Begonias and coleus are also good plants for coloring up shady areas.

You can make a child's garden by planting all the leftover one-of-a-kind plants from the spring planting spree, and letting them all grow together.