Grumpy Answers Your July Gardening Questions
1. Wormlike things made of sawdust are coming out from the branches of my crepe myrtle, and those branches are dropping their leaves. I don't want to lose the tree. Help, please. —Charles
Grumpy Says: Your crepe myrtle is infested with Asian ambrosia beetles. Female beetles bore into the trunk and branches to deposit eggs. The beetles won't harm the plant, but the ambrosia fungus the beetles carry will. It prevents water and nutrients from moving up and down the tree, which eventually causes it to die. Seriously infested plants can't be saved. My advice right now is to cut off the affected branches and burn them or throw them out with the trash. Then treat your tree according to label directions with a systemic insecticide called Bayer Advanced Tree & Shrub Insect Control. You'll need to apply it once every year.
2. My tomatoes are rotting on the bottom. What can I do to stop this madness? —Donnie
Grumpy Says: Eat them from the top. Just kidding. Your tomatoes have a condition called blossom-end rot. It happens when the plant fails to take up enough calcium from the soil. There are two principal causes. First, the soil is too acid and doesn't provide enough calcium. To fix that, spread a cup of lime around the base of each plant, and water it in. The second possible cause is if the soil stays too wet so the roots can't absorb enough calcium. Mulch your plants to keep the soil evenly moist.
3. I have a beautiful flowering cherry tree that was the envy of the neighborhood. A tree company cut off a branch hanging over the house. I thought the tree looked unbalanced, so I cut back all the branches until there were only six large ones left with no side branches. Did I mention I did this last July? The tree immediately sent shoots out from all over the cut branches; then the shoots died. Now my tree is bare, and I think I have killed it. How do I know if I did? I'm very embarrassed, and neighbors ridicule me for my chopping as they walk by! —Elizabeth
Grumpy Says: When you prune a tree so severely, it responds as yours did by sprouting fast-growing shoots to replace the lost leaves. But because they started growing so late in the year, they didn't harden off in time for fall, and a frost killed them. I doubt your tree is completely dead, though. To test, scratch the bark on the trunk and the remaining branches to see if you can find a green layer underneath. If you can, the trunk and branches are alive. If not, they aren't. FYI, the best time to prune a spring-flowering tree is right after it finishes blooming. And no, you may not cut my hair.
4. What is that small light blue moth I see fluttering all about my yard? Should I kill it? I am in a foul mood since my river birch died. —Cynthia
Grumpy Says: Whoa! I don't know what kind of moth that is, but you should never kill something unless you know that it is harmful. Taking out your tree grief on the poor moth won't bring back your river birch. Have a nice cup of chamomile tea instead. If it makes you feel better, river birch is a very messy tree, so maybe that moth did you a favor.
5. My neighbor's invasive bamboo is now taking over our backyard. We've tried spraying it with Roundup and digging up the roots, but it always comes back. What can we do? —Pat
Grumpy Says: You can only control the bamboo in your yard. As long as its roots live on your neighbor's property, they'll keep spreading onto yours. One easy control method takes advantage of the fact that bamboo sprouts only in spring. The new shoots make all of their growth in one year. So when new shoots pop up in your yard, wait until they're a foot tall and then either kick them over with your foot or cut them off at the ground. No more shoots will emerge until next year. If your neighbor would do the same thing, the roots would starve in a few years. Until he does, refuse to invite him to neighborhood potlucks.
6. Is it necessary to cut off the old blooms from crepe myrtle? —Jeff
Grumpy Says: In a word: No. However, if the tree is small enough for you to reach the old blooms, cutting off the spent ones before they set seed will produce a second bloom, usually in September. Once the plants get too big for this, however, that option closes.
7. We're having a very rainy summer, and rust-colored spots and streaks have appeared on the leaves of my daylilies. They're an old, double-orange variety given to me by a neighbor. Do I need to eradicate them and start over with a different kind? —Kathy
Grumpy Says: Don't eradicate them, but do take action. Cut all foliage off at the ground and throw it out with the trash. When the new leaves get about a foot high, spray them according to label directions with either Immunox or Natria Disease Control. Remove and throw out all withered foliage every winter. To avoid future disease, don't wet healthy foliage when you water. FYI—your daylily sounds like an old pass-along plant called "Kwanso." It spreads quickly. You can't kill it.
8. I cut my first "Sweet Basil," rinsed it, wrapped it in a paper towel, and stowed it in the fridge. In the morning, the leaves were dark brown with dark spots. What happened? —Cheryl Ann
Grumpy Says: Never wash herbs or veggies from the garden until just before you use them. Mold and fungal spores are everywhere. Wrapping moist leaves and putting them in the fridge creates the prime condition for fungi to grow.
9. I live in Mississippi but spent five years in Minnesota. While there, I fell in love with the intoxicating scent of lilacs. What kinds would tolerate my Zone 8 (Lower South) climate? —Eadie
Grumpy Says: Most Southerners would have to be pretty intoxicated to plant lilacs. These Northern favorites like long, cold winters. When they don't get them, they burn up and don't bloom. The Middle South (USDA Zone 7) is the Southern limit for fragrant old favorites like 'President Lincoln' (Wedgwood blue) and 'Charles Joly' (double, purplish red). However, the following heat-tolerant lilacs extend that range into the Lower and Coastal South (USDA Zones 8 and 9): 'White Angel,' 'Bloomerang' (light purple or reddish purple flowers), 'Blue Skies,' 'Blue Boy,' and 'Lavender Lady.'
10. I've watered and fertilized my roses, but they give only one or two blossoms at a time. They actually bloom better during our Houston winter. Can you tell me what is wrong with them? —Garry
Grumpy Says: You probably have hybrid tea roses. These popular plants often go nearly dormant during the peak heat of summer, and flower production declines. But if you keep watering and fertilizing them, the flowering should increase this fall. And cheer up—most people (especially those poor souls who live in Minnesota) would love to see roses in winter.
11. This is our first year to grow watermelons. The plants are thriving and producing lots of melons, but now they're starting to rot on the bottom and burst open. It's very hot, so I water twice a day. Is this the cause? —Barbara
Grumpy Says: Exactamundo! When it's really hot and you douse a melon plant with water, it absorbs the water too quickly. The melons swell up and burst. The rot is likely caused by melons sitting on wet ground. You can solve both problems by spreading 2 inches of pine straw under the plants and fruit to keep the fruit clean and even out soil moisture. Water only in mornings.
12. The leaves of my crepe myrtles started shriveling and dropping. Now my trees are almost bare. I know they're getting enough water. Any suggestions? —Beverley
Grumpy Says: A leaf spot disease called Cercospora is becoming more and more common. It causes leaves to turn red and yellow and drop prematurely. Fortunately, even a naked tree will bloom next year. You can prevent the fungus by spraying it according to label directions with a systemic fungicide called Immunox starting in early summer.
13. We're trying to choose a pair of shade trees to put 30 to 50 feet away from our home. We want to have nice fall color and to be able to grow grass under them. Which should we choose: Chinese pistache or thornless honey locust? —Kara
Grumpy Says: Chinese pistache! It grows quickly to 35 feet tall, tolerates almost any well-drained soil, takes drought, and has no pests. Plus, the leaves turn glorious shades of scarlet, orange, and yellow in fall.
14. I moved to Georgia last summer and planted peonies. They came up without a single bloom! What gives? —Cyndi
Grumpy Says: There are several possible causes for this. First, not all peonies like the South's summer heat. 'Festiva Maxima' and 'Sarah Bernhardt' are two that do. Second, make sure your plants receive full sun, and don't cut back the foliage until it turns yellow in fall. Third, plant so the fat buds on the roots, called "eyes," are no more than 1 inch deep. Finally, new peonies often take a year or so to get settled and start blooming, so be patient.
15. Will deadheading my 'Becky' Shasta daisies prolong blooming? —Jeniffer
Grumpy Says: In gardening terms, "deadheading" doesn't mean tripping to Jerry Garcia. It means promptly cutting off old flowers to prevent seed production and encourage plants to make new flowers. It also keeps plants that drop lots of seeds from becoming invasive. 'Becky,' a tall heirloom form of Shasta daisy, benefits from this, as do many perennials, annuals, and summer-flowering shrubs. So clip away! Faded flowers may be dead, but future daisies will be grateful.
16. A squirrel just used the branches of our Encore azalea to make a nest. He cut it down to a stump! If we spray our other Encores with Hot Pepper Wax, will it save them from a similar fate? —Nancy
Grumpy Says: Hot Pepper Wax is a capsaicin-based spray that lasts a few weeks when sprayed on branches and leaves. Any squirrel biting into it will think he's sampled Crazy Ed's 12-Alarm Chili and start begging for a glass of milk. Hot Pepper Wax (available at garden centers or biconet.com) is also good for repelling other pests such as rabbits and insects that chew or suck. Apply it according to label directions during the coolest part of the day.
WATCH: Planting Azaleas with the Grumpy Gardener Video
17. That creeping Bermuda grass is taking over my flowerbeds! Is there something I can use against it? Or should I just wave my white flag now? —Patti
Grumpy Says: Patti, don't surrender! Instead, load up with good ammo. There is a product on the market that kills only grasses and doesn't harm broad-leaved plants such as perennials and ground covers. It's called Ortho Grass-B-Gon, and it's exactly what you need. Follow label directions carefully, and then surrender to an episode of Modern Family.
18. I need an 8-foot-tall privacy screen for a 3-foot-wide bed in our side yard. What can I plant to create some privacy without it looking like I hate the neighbors? —Mary
Grumpy Says: Select upright, narrow shrubs without sharp thorns that can impale people. Two good candidates that come to mind are 'Green Tower' boxwood and 'Sky Pencil' Japanese holly.