GARDENING; Old Pests, New Pots and Soil Mixtures
By JOAN LEE FAUST
Published: September 22, 1991
SOMETIMES house plants have to be discarded. This is what happened to a beautiful Boston fern that was looking rather sad the last few weeks with many yellow or, worse, dead fronds. Since it was hanging in a strategic place, closer inspection was needed to determine the trouble. The elegant Boston fern hanging next to it didn't need a sad partner.
So down from its hook came the yellow Boston fern. The first thought was that it just needed repotting, as it had been rather crowded in its hanging container. But upon close inspection, the source of the problem was revealed: scale insects. These oval hard-backed insects were adhering to the backs of the oldest fronds in huge numbers.
Since these insects are serious troublemakers as far as any house plants are concerned, the obvious solution was to cut out the older fronds infested with the scale. Although scale look harmless, underneath the protective shells are needlelike mouths that suck sap from stems and leaves.
Once established on the plant, scale is difficult to control. Only in the mobile stage of the life cycle is the pest vulnerable to sprays, and even then, sprays rarely attack the entire population.
The solution here? Toss out the plant, promptly, lest its scale population transfer to the neighboring fern.
Lesson learned. Inspect house plants often. And not just the tops of the leaves, but the backs, too.
At this time of year many potted plants have been summering outdoors and must be taken indoors promptly if they are to adjust to less light and air before the house heat comes on. If insects come into the house on these plants, the pests will be almost impossible to control, as they will have free run of everything green indoors.
Some of the worst pests to be aware of are mealybugs, white flies and red spider mites. Mealybugs are especially keen about hiding underneath and in the joints of cactuses and succulents. Inspect these plants with great care, especially pots of cactus in desert gardens; all sedums, like burro's tail and jelly beans, and any of the crassulas, particularly jade plants. Also check echeveria, lithops, string of beads and other succulents to be sure they are clean.
Mealybugs suggest cottony masses in between the joints and along the stems. If these insects are seen, wipe them out with a cotton swab dipped in rubbing alcohol. Do this thoroughly and inspect the plants every few days to be sure that the nymphs were cleaned off. Sometimes the task must be repeated two or three times to be sure of getting the plants clean.
As for white flies, never take the insects indoors, if it can be helped. Check all geraniums before taking cuttings to grow as house plants in winter. Be sure the plants are not near petunias, ageratums or even tomato plants in the garden, as these plants are favorites of white flies. If there are white flies on the geraniums, isolate the pots of plants for a few days before taking cuttings to be sure the plants are free of them.
Red spider mites have been plentiful this summer. If house plants have been less than beautiful and the foliage has appeared dusty, suspect spider mites. These mites thrive on dry foliage and in high heat. The best way to get rid of them now is to set the pots on their sides on the lawn and turn on the hose onto the plant foliage. Turn the pots every few seconds to be sure of rinsing the leaves and then stand the plants upright for a few hours to drain. Then inspect the leaves carefully before taking the plants indoors.
Plants that have been set in the ground for the summer -- like amaryllis, gardenias and camellias -- may have grown so vigorously that the roots have anchored into the ground. If this has happened, simply turn the pot a few times to loosen the roots, then give a good tug. The roots will break loose, and by all means repot the plant into a container one size larger. If any of the other plants set on the terrace, patio or porch seem to be bursting out of their pots, repot them similarly. (Of course, the plants should be knocked out of their tight old pots before they are set into the new pot, with a fresh mixture of potting soil at the base.)
Although there are ample packaged potting mixtures for sale at garden shops, the old standard one-one-one mixture (equal parts of clean soil, sand and compost) is still tops. To be sure that soil does not run out of the drain hole in the new, larger pot, place a square piece of plastic window screening over the hole.
There is one exception to bringing all of the house plants indoors now: Christmas cactus. Leave this plant outside until one or two frosts have touched it. This simple gesture will force the setting of flower buds and allow the plant sufficient time to form good flowers for the Thanksgiving-Christmas season. Of course, many people bypass this stage and have the flowers, anyway. But this simple act helps insure that the plant will flower this fall.