Watermelon ripe when tendril turns

Q: I have a hard time telling when my watermelons are ripe. They have been the size of a cantaloupe for several weeks. — Jerry Hox, e-mail

A: Watermelons can be slow to fully ripen because they depend so much on the right ratio of leaves to fruit. Leaves make energy that the fruit turns into sugar. If there aren’t enough leaves to serve all the fruit, none of the fruit grows large or ripens fully. The exact ratio is loosely defined, but my guess is that you need to remove some of the fruit from your vine. Examine the vine to find the small tendril across from the fruit stem. When it turns yellow, the watermelon is ripe. More details at xrl.us /harvestfruit.

Q: I have bags of azalea fertilizer that are 4 years old. Would it harm my shrubs to apply the fertilizer this fall? — Steve Herndon, Smyrna

A: My rule of thumb is to apply fertilizer to a plant when it is actively growing. Some plants benefit from fall feeding, but there is always a risk that fall feeding will lead to new growth just before a freeze. To be safe, apply the fertilizer in February according to label directions. It may be lumpy in the bag, but you can pulverize it with a hammer and use according to label directions.

Q: I have been unsuccessful in finding rotenone, an organic insecticide I have used for many years. Where can I get some? — Lollie Bohannon, Alpharetta

A: Rotenone has been used as an insecticide for more than 100 years and as a fish poison for more than 1,000 years. It is derived from the roots of tropical plants. These days, in order to balance the threat to fish in nearby streams with the need for organic insecticides, rotenone is usually mixed with pyrethrin, another organic insecticide. You should be able to find it locally and online from companies that specialize in organic gardening.

Q: My azalea had caterpillars clustered at the tip of the limb. Should I spray all plants, or just watch for caterpillars and then spray? — Dianne Dye, e-mail

A: Azalea caterpillar is an occasional autumn pest of azaleas. They defoliate random azalea limbs, but they will not kill the plant.

You can spray insecticide on them as you see them or simply wait for natural predators to kill them. Hornets and paper wasps find these caterpillars a delicacy.

Q: What would you recommend as a fast-growing ground cover in sunny and shady areas? — Glenn Moran, Monroe

A: For shade, I like Lenten rose or mondo grass. For sun, spreading juniper and purple euonymus are hard to beat. For more ground cover options, visit xrl.us/groundcover.

Listen to Walter Reeves from 6 to 10 Saturday mornings on AM 750 and now 95.5 FM News/Talk WSB. Go to www.yoursouthern garden.com for details on his TV show or visit his website, www.walterreeves.com.