Q: I think this insect fell from my maple tree [the reader sent a photo]. No one seemed to know what it was, so I finally googled "fuzzy green caterpillar" and came up with American dagger moth. Do I need to be concerned?
A: It is a dagger moth. There are several species, with the largest being the American dagger moth. The adult moth is a small, grayish white moth, fairly nondescript, but the larvae or caterpillar is something to behold. The large, greenish-yellow caterpillar has four bunches of black bristles on the body. The black bristles, or spines, can break off and embed themselves in human skin. The spines contain a toxin that can cause an allergic reaction, so avoid them. The larvae feed on a variety of shade trees, including maples. They won't cause much damage to the tree, but avoid picking one up.
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Q: I have two really great geraniums, and they are blooming. What can I do to save them from winter? Should I cut them back and put them in the garage?
A: Even though we grow geraniums as annuals, they have a much tougher, almost woody stem, unlike most annuals with tender, herbaceous stems. Geraniums will also handle some light freezes and actually bloom fairly well in cooler weather. This means they can be planted earlier in the spring and will last later in the fall. They do not need to be exposed to a hard freeze, however. You have several options for overwintering them. You can take them indoors as a houseplant — they won't be happy and will get leggy, but they will survive. You can also move them into the garage or crawlspace of your house to prevent them from freezing. Some older gardeners used to remove them from their pots, shake the soil off and hang them in the attic, and replant them next spring (probably not a 100% survivor rate with this). Whichever option you choose, instead of cutting them back, unless they are huge, leave them intact, because they will die back. Cut them back and repot when you move them back outside in the spring.
Q: I have 35- to 40-year-old photinias that I would like to at least cut by a third. They are 25-40 feet tall. When would be best time to do that? In fall or spring?
A: Fall is not the time to prune anything hard. Pruning now would leave you with a "cut" plant all winter until new growth begins in the spring, and that would expose the plant to cold damage, should we have a severe winter. Normally I would say severe pruning should be done in late February to early March, to allow the plants to recover quickly with new growth. The one concern I have for red top photinias is their potential disease concerns — a leaf spot problem. Rapid new growth tends to be more susceptible to the disease. So, another option would be to allow the spring burst of growth and prune in late spring — early May. This would still allow recovery before hot weather hits but hopefully prevent extremely rapid new growth, which dormant pruning often promotes.
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Q: My grandmother's home place is being sold, and all of us grandchildren have fond memories of playing in her huge old magnolia tree. Is there some way we can grow another tree from the one she has, and if so, how do we go about doing it?
A: Magnolias can be started from seeds, cuttings or layering. You should be seeing mature, ripe seed pods now. The cones containing the seeds will begin to darken and dry, and the emerging red seeds will be visible. Try to harvest as soon as they are ripe, and begin the preparation process as soon as possible. Don't store the seeds for later use. Take the seeds and remove the outer pulp. Magnolias have a hard outer seed coat, so it would help to scarify, or break, the hard outer seed coat before planting. To do this, lightly rub the seeds between two sheets of sandpaper or inside one folded sheet. Then place the seeds in a plastic bag filled with moist peat moss or potting soil. Place that in your refrigerator for several months, then pot them up and wait for them to begin growing. The combination of scarification (the abrading of the outer seed coat) and stratification (the cool, moist storage period) should result in seedlings. This process happens naturally outdoors, so you also might find some seedlings growing on your grandmother's place that you could dig and transplant. Cuttings are best taken in June to July from new growth that has gradually hardened off. An easier method than cuttings is to layer some of the lower limbs of the tree. Take a low hanging branch and lightly wound its bottom side, bend it to the ground and mound soil over it. Weigh it down and wait until next spring. By then it should have sprouted roots and can be cut off the main tree. Which option you use depends on how much time you have.
Retired after 38 years with the University of Arkansas Cooperative Extension Service, Janet Carson ranks among Arkansas' best known horticulture experts. Her blog is at arkansasonline.com/planitjanet. Write to her at P.O. Box 2221, Little Rock, AR 72203 or email email@example.com