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Jul 01, 2023

The Plant Doctor: When to prune common impatiens?

Question. We have several plantings of the common impatiens that have grown lanky. What will happen if I give them a light pruning? Answer. After a number of years without the common impatiens due to

Question. We have several plantings of the common impatiens that have grown lanky. What will happen if I give them a light pruning?

Answer. After a number of years without the common impatiens due to a devastating disease, it is great to see them back in the landscapes. At one time, this was the number one bedding plant in the nation. Luckily, disease-resistant varieties are now available as seeds and plants at garden centers. Healthy impatiens withstand heavy pruning and can be expected to grow and flower in a matter of four to six weeks. Do realize after pruning, the plants are not going to be attractive for a while. Maybe light pruning now that removes only the most lanky portions would be best so they can be as attractive as possible heading into fall. Keep the soil moist and apply a fertilizer where permitted shortly after pruning.

Q. It’s time for us to plant a garden, and we want to grow cherry tomatoes. Do certain varieties do better than others?

A. Now is the time to plant tomatoes for a fall harvest. Cherry or small-fruited tomatoes appear more heat-tolerant and may fruit early in the fall. Most varieties seem to grow well locally. Some selections I have personally grown and obtained good harvests include Sweet Million, Sweet Treats, Cherry Princes Sweet Surprise, Juliet, Unicorn and Snow White. All are indeterminate and need a trellis or cage to grow upwards.

Q. Large orange to brown grasshoppers are feeding on our crinum and amaryllis plants. What are they, and is there a control?

A. A few months ago, a warning was sounded that small black and yellow to red-striped grasshoppers found in local landscapes were going to become monsters. This year, the lubber grasshoppers seem more prevalent, feeding on any broadleaf lily-like plant foliage. Many have grown to three to four inches in length. They also chew the leaves of citrus trees and many ornamentals. The time to control these critters is in March or April, when they are small and can be collected and dumped in rubbing alcohol. At this time, they are mature and brown to orange color. Insecticides are normally only effective when the grasshoppers are small. At this time, hand picking and tossing in rubbing alcohol or putting under foot is the only good control.

Q. I have queen palms that have grown too tall to trim conveniently. I was wonder if cutting out the new growth at the top will stunt the palm.

A. Hold the pruners for a little lesson in palm growth habits. There is only one bud that produces all the growth, and guess where it is found? Yes, in the very top of the palm. So, you can remove the fronds back to the trunk and the flower and seed stalks, too, but don’t touch the trunk portion. Cutting out the tops of the palms would likely be the end of a landscape planting. If the palms are growing out of reach, you may want to hire a palm care company to do future trimmings.

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Q. Our three-year-old geranium plants have been attractive but with all the summer heat, they have gotten ugly. Should I pull them up and obtain new plants during the fall, or should I cut these back and see if they can make new growth?

A. Heat, humidity and rains make most geraniums look ugly during the summer season. Many gardeners would have given up on their plants a long time ago but you haven’t. So, I suggest you stick with them a little longer. The plants are only about two months away from good growing weather when geraniums start to revive. Trim the declining portions back a little, but do not remove all the foliage that is producing food to keep the plants alive. Keep the plants in bright light but out of the rain. You can provide a light feeding or two each month and water when the surface soil begins to dry to the touch. I bet your plants are going to make it through another year with this good care.

Q. Our hedge is growing out of control. Is now a good time to do the pruning, or should I wait for cooler weather?

A. Don’t delay the rejuvenation pruning of your overgrown hedge any longer. If the hedge is healthy, it can withstand severe pruning to encourage a more compact growth habit. Leaves that remain on the plant may suffer sunburn but new growth should hide the damage. If the hedge is given a severe pruning, the new growth can be slow starting. By pruning now, you allow adequate time for the planting to fill in with mature stems before cooler fall and winter weather. Keep the soil moist and fertilize when permitted.

Tom MacCubbin is an urban horticulturist emeritus with the University of Florida Cooperative Extension Service. Write him: Orlando Sentinel, P.O. Box 2833, Orlando, FL. 32802. Email: [email protected].

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