Hold Everything : You Can Grow All Kinds of Flowers in Pots--and in the Places You Might Never Have Considered

Potted flowers are always a possibility where there seems to be no place for plants at all: A window right next to a driveway is the perfect place for a window box; a patio that has a little too much stone can be made more hospitable with potted flowers. That is how containers were used in the two gardens pictured here, and you can probably find even more places for potted plants in your own garden.

Growing things in containers is not difficult, but it does require diligence. Plants firmly rooted in the ground forgive a missed watering, but those confined in containers won’t. And plants growing in the garden can forage for food, but this isn’t true for those in containers.

At this time of the year, you may have to water potted plants growing outdoors daily. It’s possible to overwater, but it’s not likely--especially for the annual flowers shown here, which grow so rapidly. Much more common is letting them get too dry; even one drying-out can stunt their growth forever.

Modern potting soils do not hold much moisture in reserve. They are designed to be fast-draining--the water runs out almost as fast as you pour it in. This prevents overwatering--the most common killer of plants--but it also means you must irrigate nearly every day, as they do at nurseries. Diligence.

It’s easiest to buy a packaged potting soil, but you can make your own. The Sunset book “Gardening in Containers” offers a good recipe that is based on the so-called UC Mix, developed by the University of California for commercial growers:

2 cubic feet of nitrogen-stabilized ground bark, peat moss or other organic material

1 cubic foot uniform fine sand or sandy loam

1 cups 0-10-10 or equivalent dry fertilizer

1 3/4 cups dolomite limestone

Note that this potting soil can be made without using real dirt, but the latest word in soil mixes suggests that a handful of ordinary dirt be tossed in to inoculate the mix with beneficial soil bacteria. You may wish to use coarse sand instead of fine sand for even better drainage, or you may opt to use sandy loam (available at places that sell “topsoil”), which will drain more slowly so you need to water less often.

Because most potting mixes are so porous, the water carries much of the fertilizer right out the bottom of the pot, so you need to fertilize almost as often as you water. Commercial nurseries fertilize every time they water, using special equipment that puts minute quantities of fertilizer into the irrigation system. You can do almost as well by fertilizing every week. Use a liquid fertilizer; the label will usually recommend how much to use monthly, so divide that amount by four if you feed weekly.

In addition, you may want to add a dry granular nitrogen fertilizer to the potting soil mix before filling the containers, but this doesn’t take the place of weekly feedings. A piece of window screening placed over the drainage hole will help keep the soil in and creatures like sow bugs and slugs out.

If you faithfully follow this regimen of watering and fertilizing, you’ll be astounded at how well things grow in your containers, though there is one other trick used by good gardeners: Don’t use small containers (this is apparent in the photographs). Large ones stay cooler in the summer, and the plants’ roots are that much happier.

Many gardeners prefer to grow only annuals, or perennials treated as annuals, in containers. The reason? They can take a break from the routine of watering and fertilizing, in between seasons. Right now, for instance, you can plant summer annuals like those growing in the window box pictured here. These will last into early fall but must then be dumped, soil and all (the soil can be used in the garden, but don’t reuse it in containers, because it has been depleted by the flowers).

Now you can leave the containers empty for a few months until the urge to garden hits again. Later in the fall, or in late winter, replant the containers with spring flowers, like those growing in the artful grouping of pots.

With this schedule, you’ll have color when you are in the garden most often, during spring and summer. In both plantings, several common plants look and do best grown in containers, including geraniums, alyssum, lobelia and petunias. All are trailing plants, and in pots they spill over the sides--another reason to try planting in pots.

And don’t be afraid to put several kinds of flowers in the same pot, as has been done here--taller plants to the inside and trailing types at the edges. The effect is a little more casual, but it’s also more complete because the pots are little gardens all to themselves, having the charm of a 17th-Century Dutch still life.