Question: We purchased a blue flowered agapanthus in a container and have both sun and shade. Where does it grow best and what care is needed?
Answer: Sunny garden sites are recommended for agapanthus, also know as Lily of the Nile. But locally, lightly filtered sun to morning sun and light afternoon shade seems best. Besides the powder blue flower varieties there are also purple and white colors available. Plants flower best after they form clusters so you might avoid dividing until they grow quite dense. Keep moist but not overly wet spring through early fall then allow to remain on a slightly dry side during cooler months. Old flower heads can be removed as needed to keep the plants attractive.
Q. Our poinsettia from over a year ago is in the ground and now about four feet tall. Can we still do needed pruning?
A. Pruning continues throughout the spring and much of the summer months for poinsettias. You are on schedule to cut your plant back about a foot or more. Then allow 6 to 8inches of new growth until you remove another 2 to 4 inches from tips of the main shoots. Continue the latter pruning regime until the end of August when all trimming except for errant branches should stop as the poinsettias mature and eventually produce the colorful shoots. Where permitted, fertilize with a slow-release product as labeled and keep moist. Also, be ready to control insects and mites that could damage the leaves.
Q. We inherited a 10-foot-tall gardenia when we bought our house that just finished flowering. Could or should we do pruning now?
A. Sounds like you have a very attractive and likely quite fragrant gardenia shrub. Unless the shrub is overgrown for the site, very little pruning is needed. Some varieties continue to produce sporadic blooms throughout the summer which you could still enjoy. Where needed, pruning can be performed at this time to remove out-of-bounds shoots and reduce plant height and width. Recovery should begin in a few weeks from healthy plants. Gardenias need good care to remain attractive, that includes a moist soil, fertilizer three to four times a year as permitted and sprays to control scale and similar insects. Some also develop yellow leaves — a magnesium deficiency — that can be cured with an Epsom salts application at label rates.
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Q. My delphiniums had great blooms, but since blooming the plants look like they are dying? I did remove the flower stalks but the plant looks weak. Is this normal?
A. In Florida your delphiniums are performing normally. The plants often grow as short-lived perennials in cooler climates but with the late spring and summer heat, plus seasonal rains, local plantings gradually decline. The lower stems and roots rot due to the growing conditions. New Central Florida plants are started from seed each fall or purchased from garden centers for winter or early spring planting.
Q. I am covering my garden to bake out the nematodes. Are any vegetables besides tomatoes affected by these pests?
A. Very few vegetables escape a nematode attack. Some Southern peas and resistant tomato varieties are not affected as much but other vegetables might be considered nematode bait. It’s best to reduce the nematode populations by covering all tilled and moist garden sites with clear plastic to bake out the pests for six to eight weeks during the summer. This treatment also controls some weeds and vegetable diseases, too. If you cover the soil now, you should be ready for planting by mid- to late-August.
Q. Please tell me about the century plant, as I have a big one in bloom. What happens after it is finished flowering?
A. Finished is the best word to describe a century plant when it shoots sky high to produce its blossoms. The tall stalk with the greenish-yellow blooms at the top grows to 20 feet tall in a few weeks then declines. In fact the whole plant dies. It is probably best to cut the flowering stalk down when the blossoms fade to keep it from falling over as it weakens. The mother plant then gradually declines, but don’t feel too bad as there are normally a number of offshoots forming at the base to carry on the tradition. Oh yes, if you are wondering, it only takes the plants six to 10 years to flower again. It just seems like a century.
Q. My pineapple plant is producing its first fruit. Once the pineapple is harvested will the plant produce more fruit later?
A. Get ready for a succession of good eating but not from the same plant. A pineapple plant only produces one fruit. But wait, there is good news — additional plants usually grow from the base to continue the production. The mother plant gradually declines as the new plants form. You can leave them to grow a cluster of fruiting plants or remove a few when they are 8 inches or so tall to expand the pineapple patch. If left mostly intact, the planting normally produces more fruit within a year.
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: TomMac1996@aol.com.
