1. Archive


The September garden calls attention to perennials and pest control.
Published Sep. 9, 2009

While you may be thinking ahead to the goodies you'll grow in your fall and winter garden, September is a good time to provide some TLC to your flower beds. By dividing perennials now, you can control the size of the plants and ensure better bloomers. Here are three favored perennials in the bay area:

GINGERS are among our finest perennial plants. Shell ginger (Alpinia zerumbet), above, is a vigorous grower that produces magnificent pinkish, shell-shaped flowers looking much like a cluster of grapes. During the summer months, gingers produce an abundance of growth. To assure continued good growth next year, dig up the rhizomes now. Propagate the plant by cutting the rhizomes, leaving an immature sprout or two on each section. Plant the rhizomes about 2 to 3 inches deep. Gingers require little care other than moist soil, afternoon shade and occasional fertilization.

DAYLILIES (Hemerocallis spp.) are now beginning a short period of dormancy. As daylilies age, they produce a thick clump of growth that weakens plants so they do not bloom well. Divide them by digging up the entire clump and separating each individual plant or fan. Replant them a little higher than they were in the original clump. (There will be large, tuberous growths on the root system; do not remove these storage organs. They help promote growth.)

STOKES ASTER (Stokesia laevis) is another perennial that has a tendency to become too dense. The long, large roots may be reduced to make transplanting easier. Like daylilies, there are many plants within the clump. They should be separated and set slightly higher than their original depth.

* * *

Divide and conquer bulbs

September also is the time to dig bulbs. Separate and plant the small bulbs that form around a large central bulb, then replant the older bulb. Amaryllis (Hippeastrum) has a tendency to draw its bulbs into the ground. When replanting, make sure that the top third of the bulb is exposed to ensure blooms. This applies to other bulbs in the amaryllis family, including spider lily (Hymenocallis spp.) and rain lily (Zephyranthes spp.). The large native crinum or swamp lily (Crinum americanum) can also be divided now.

* * *

Palms susceptible to new disease

New diseases are proving deadly for a number of landscape palms. Texas Phoenix Palm Decline is caused by a bacteria and is affecting trees in the date palm family (Phoenix spp.), as well as queen palms (Syagrus romanzoffiana) and sabal palms (Sabal palmetto). The first obvious symptom on mature palms is a premature drop of most or all fruits. The oldest (lowest) fronds also will discolor beginning at the tips, among other symptoms. Texas Phoenix Palm Decline can be treated with injections of an antibiotic called OTC if caught early, but untreated trees eventually die.

Fusarium Decline also has been a problem for queen and Mexican fan palms (Washingtonia robusta). This disease is fatal for infected trees since there is currently no treatment. Learn more about the diseases at Search for "palm diseases."

* * *

Battling those no-good pests

Check citrus, gardenias, camellias and other plants for signs of a damaging infestation of whiteflies. One sure indicator is the presence of black, sooty mold on the tops of leaves. The nymphs feed on the underside. To get rid of them, try yellow sticky card traps. Adult whiteflies are attracted to yellow, so place the cards near the plants. As the flies mature, they will fly to the cards and get stuck. Chemicals also can be used, but follow label directions carefully as some chemicals are not labeled for certain plants.

- Inside, check houseplants for fungus gnats and spider mites. The adult fungus gnat is very small and usually dark brown to black. The larvae live and feed in potting soil. (The adults do not feed.) Both larvae and adult fungus gnats are attracted to moist soil, and their presence usually indicates that the plants have been overwatered. Allowing the soil to dry out for a few days or a week may be the best control. The larvae rarely attack healthy plant roots or stems. Tiny spider mites may be greenish, yellowish, reddish or virtually colorless. Mites suck juices from plants, causing a speckled appearance called stippling. Gently washing the plants with water periodically can help control spider mites, as can increasing the humidity around the plant.

- In your lawn, be on the lookout for armyworms. Armyworms are the larvae of moths. When full grown, the larvae are about 1-1/2 inches long, yellowish brown to black with a wide, dark stripe on each side of a stripe that ends in an upside-down Y on their heads. Their feeding can cause circular bare areas in the lawn. Apply pesticides carefully according to label directions.

* * *

Time to get out the shears

- Prune bougainvillea before the middle of the month to ensure good blooms this winter. Fertilize lightly with 12-4-8, 15-0-15 or other similar mixture labeled for acid-loving plants.

- The beginning of September is the last chance to prune your poinsettia. The rule of thumb is not to prune after Labor Day. Keep the plants watered and fertilize lightly.

* * *

Appreciation for the wasp

Insects such as hornets, yellow jackets, mud daubers and cicada killers are all wasps. They are generally considered beneficial because they attack and destroy many harmful insects found around homes and gardens. Hornets and yellow jackets, for example, kill houseflies, blowflies and various caterpillars. But wasps also can attack people. They nest above and below ground and can be aggressive. To control these pests, use a wasp and hornet spray for quick knockdown.

Carol Suggs is with the Pinellas County Extension Center/Florida Botanical Gardens. Pam Brown recently retired from there. For more information, visit the extension Web site at or call (727) 582-2100.