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Talk to the Annuals

Posted: July 12, 2011

 Now that it’s the end of June, take a look at the annuals you enthusiastically chose and planted in May. You probably worked very hard at selecting just the right combinations of colors and textures. You prepared your soil and amended it or added compost if necessary. You waited till after May 15 to plant to guard against an unexpected freeze; and you’ve been watering faithfully to encourage the small plants or seedlings to grow. You matched your plants to the proper location--sun-loving plants in at least six hours of sun; shade plants in dappled shade.

What else should you do to keep your annuals looking vibrant for the rest of the summer?

The most basic maintenance should be to deadhead your plants. Most annuals should be deadheaded; otherwise the spent blossoms turn into seeds. The plant is then using its energy to reproduce. If you cut those dead flowers off, the plant will continue to produce new buds and blooms. Annuals are programmed to grow fast, bloom, and produce seeds all in one summer. No wonder they need some help to look good till frost comes and kills them.

One of the most popular annuals is the Wave petunia. It was developed probably less than 10 years ago and has been improving ever since. Its main claim to fame is that it is self-cleaning (doesn’t need deadheading). This petunia grows fast, covers a lot of space, and comes in many beautiful colors except yellow. I am not alone in my aversion to the tedious job of deadheading the sticky flowers on regular petunias. By the way when deadheading petunias, you must pick off the wilted flower along with the seed (it is a hard, bead-like growth within the flower).

Frequent watering may not be necessary once the plant gets off to a good start. If you watered deeply when you first planted, the plants are probably getting full and bushy by now and their leaves and stems will provide enough shade to keep the soil moist. And certainly you covered the soil with compost or mulch to retain moisture. Of course if the weather is sunny and windy, the plant may become stressed and need more water. A windy day can create more stress than the sun. On the other hand cloudy, rainy days can retard prolific blooming. Geraniums, especially, like it hot and dry. They will be slower to set buds if there are a lot of cloudy days, and rain really destroys the flower heads.

Something else your annuals need throughout the summer is regular fertilization (keep a schedule). When you planted annuals in containers, possibly you included a slow-release fertilizer in the potting soil but don’t stop there. Every time you water your container, some of the fertilizer leaches out. Remember, containers may need watered every day or even twice a day depending on the container size and the outdoor temperature. Many people use diluted fertilizer such as 20-20-20 at half strength every time they water. You can also use a foliar fertilizer by spraying the leaves. Fertilize at least once a week in a container.

If your annuals are in the landscape, most of them should be fertilized every two weeks. Some fertilizers promote heavy bloom: if the middle number is high (10-50-10 as an example,) it will encourage compact growth and many flowers.

All of the preceding suggestions assume that your annuals are doing well already. If you find that some are just not thriving, you may want to replace them. Possibly you have been babying your pansies--this is probably a waste of time at this point. If they have gotten leggy, just cut them back and wait for fall. They will probably start some new growth and bloom again even after frost. Pansies can last through the winter and come back again next spring.

A plant that may not be thriving if you planted it too early is annual vinca (sometimes called periwinkle or Madagascar periwinkle). It needs to be planted in warm soil that has reached 70 degrees so wait until the beginning of June. Vinca is drought tolerant and needs sunny conditions. If the summer turns out to be cloudy and rainy, you might want to replace some plants with impatiens or New Guinea impatiens. Both of these do better with some shade, and they need more water than vincas.

Vincas and impatiens have similar growth patterns; they are low-growing with much branching and they form a clump. Even the flowers are similar--simple, single flowers with leaves that generally have no insect damage. Either of these plants can grow from 8 to 18 inches tall with a 1-foot spread. New Guinea impatiens are generally larger than regular impatiens, and they have much larger flowers. All three of these annuals come in a wide range of colors from white to orange, pink, lavender, and red.

Other plants to choose at the end of June are coleus that, if cut back, will continue to grow and form their colorful leaves all summer long. Be sure to cut off the blue flower spikes to keep the growth compact. Coleus can be found for sun or shade. Zinnias, especially Profusion zinnias, are still available and are plants that branch and form lots of flowers. Ornamental peppers do well in the heat of summer. They will form many peppers, and some of the varieties show the peppers in various stages of colors as they progress to ripeness. These plants will last well into fall.

Many nurseries transfer their potted annuals to larger pots (6-inch containers) as the summer progresses, so buying them now means you will have larger plants from which to choose. They may be a bit more expensive, but you will need fewer plants. If you just want to fill in a few bare spots, this is a reasonable choice.

Be sure to come to the Wednesday evening Garden Walks at the Extension Office on the first and third Wednesdays of the month at 6:30 p.m. to see how the Master Gardeners’ annuals are doing. You will get some ideas of how the annuals are thriving based on our weather.

One last thing to do to keep your annuals looking good is to check on them frequently. If you walk around your garden daily, you will notice if something is going wrong--a bug attack, a plant wilting, flowers not as big or plentiful as they should be. If you catch a problem early, you can probably correct it easily. For bugs, it may be as simple as hand-picking or using a spray of water to dislodge aphids. Don’t wait until you have to use chemicals; the chemicals will destroy beneficial bugs as well as the harmful ones. Also if you are in your garden frequently taking care of the few weeds that will inevitably appear between your healthy plants, you may discourage rabbits and other wildlife from using your garden as a buffet. And while you are there, you may want to talk to your plants--it can’t hurt. Happy Gardening.

 Martie Young is a Penn State Master Gardener from Adams County. Penn State in Adams County is located at 670 Old Harrisburg Road, Gettysburg, PA 17325, phone 334-6271 or 1-888-472-0261. Penn State is committed to affirmative action, equal opportunity, and the diversity of its workforce.