One of the pleasures of summer is hanging out on your terrace, deck or patio with an array of potted plants.
Unlike the masses of flowers in your garden proper, these singular specimens remain up close and personal through the season, living right at your feet. There are plenty of occasions to observe the intricacies of their blossoms and foliage. Let's hope they stand up to intimate scrutiny.
Too often, the plants that looked gorgeous when first set out begin to flag in the heat and humidity of high summer, despite regular watering. Droopy petunias laden with spent flowers, verbenas with foliage browned by too much moisture and foliage specimens grown lank and stringy do not present that picture of perfection you had in mind back in May, I'm sure. Do not despair, since most potted plants can be revived with a little care. The true fact is that plants grown in pots are entirely dependent on you for nutrition, water, grooming and affection. Like pets, they need a firm but kind hand to be on their best behavior.
Whether you've chosen and potted them up on your own or treated yourself to a pre-planted container from the local garden center, chances are very good that you have a selection of annuals. These include the familiar flowers of summer -- marigolds, petunias, snapdragons, impatiens, verbena, nasturtiums, zinnias -- and newer, less familiar "designer" annuals like bacopa, angelonia, nemesia, calibrachoa and celosia.
As a class of plants, annuals complete their life cycle in a single season. While they won't return next year, annuals can be induced to flower through the entire summer -- something you won't get from the average perennial. Perennial borders get their punch from a succession of different plants blooming in turn; annuals provide bang for the buck by blooming all but continuously from early summer through early fall. Or so we hope.
For starters, you need to understand the single-mindedness of annual plants, which make haste to squeeze a lifetime into a single summer. This means growing to sufficient maturity to bloom and set seed, insuring that there will be another generation. The successful act of reproduction convinces your plants that they have fulfilled their destinies and are free to expire.
You can thwart this syndrome by removing spent flowers before they can ripen into seed pods. Snip or pinch off not just the browning petals, but the structures just below the blossom, which will develop into seeds. Deprived of signals that the next generation is on the way, the plant will once again try to perpetuate itself, producing a fresh flush of flowers.
If you have few flowers and foliage has turned from rich green to pale yellow-green, chances are good your little plants are starving and are too malnourished to bloom.
Potting soil mixes often have few nutrients, which is why it is wise to buy those types that have slow-release fertilizer mixed in, or to mix this pelleted plant food in before you pot up plants yourself. Generally, I find this isn't enough to keep plants at their peak all by itself -- it's like a daily vitamin, providing essential nutrients but hardly a substitute for regular meals.
Fertilize weekly with a water-soluble fertilizer that has a formula of 15-30-15 or 20-10-20. You can alternate with a "bloom booster" formula high in phosphorus, say 10-52-10, to stimulate the production of flowers, but by all means give those guys some food. Nutrients are flushed away by daily watering and must be replenished.
When I pot up my plants, I also incorporate some compost or purchased humus to make the potting medium a little richer and add beneficial soil organisms, giving the sterile mix some life. I think it helps.
If your plants have become irredeemably ragged before you swing into action, cut the whole plant back sharply (by about a third), fertilize according to package directions and wait about two weeks.
Your plants should make a fine recovery, launching themselves into a period of vegetative growth, and shortly getting with the program by producing a new set of flowers. Don't be afraid to try this with straggly foliage plants as well, since things like sweet potato vine and coleus also rebound quickly, generating new leaves.
It's only when days shorten and cool down with the approach of fall that these strategies might fail to produce the desired result with an annual plant. Then, it's time to ditch the withered thing and move on -- to mums, asters and the other potted plants of autumn. To everything there is a season.
Valerie Sudol's "Garden Diary" appears every Thursday in The Star-Ledger. To reach Valerie, write to The Star-Ledger, 1 Star Ledger Plaza, Newark, N.J. 07102-1200 or e-mail her here.