Grumpy Answers Your Top April Gardening Questions
April really ought to be a celebration of rebirth in the garden, but for Grumpy it's also the month of high anxiety. Spring tornado season peaks right about now, usually around Easter, threatening a meeting with my Maker sooner than I had expected. I often end up spending more time watching the weather radar on TV than outside planting spring flowers.
1. Question: The sunlight reflecting off the neighbor's windows is causing our siding to bubble. What are some narrow evergreens I could plant to block it? —Janice
Grumpy Says: Wow, that's hot sunlight! Check with Google Earth to make sure you live on this planet and not Mercury. If you are, indeed, on Earth, make sure your homeowners' association doesn't allow the use of Federation phasers by unsupervised minors. Lastly, try using one of these narrow evergreens to make a screen: "Sky Pencil" Japanese holly, "Scarlet's Peak" holly, "Foster #2" holly, "Skyrocket" juniper, and "Maki" podocarpus.
2. Question: Why am I losing about 25% of my zinnia seedlings that have been in pots less than one week? Some look great, but others seem to be wilting and dying! —Elsie
Grumpy Says: This is most likely due to a fungal disease called damping-off. It is caused by keeping the soil too wet and the plants too crowded. Give the seedlings plenty of sun, provide enough space between plants so that air circulates well, and let the soil surface get a little dry between waterings. And plant seeds in fresh potting soil, not old soil, which may contain disease spores.
3. Question: Is my crepe myrtle safe for my dog? —Angie
Grumpy Says: Yes, unless it makes the tree very, very angry by teasing it with food. Grumpy receives lots of questions about which plants can poison dogs, cats, and horses. (But strangely, no one ever asks about possums and beavers.) To find out more, go to aspca.org and search for "poisonous plants."
4. Question: I purchased some starter pepper plants from the local hardware store and planted them directly into rich organic mushroom compost. They are budding, but I am not noticing a lot of foliage growth. What am I doing wrong? —Daphne
Grumpy Says: Pepper plants love the heat. In cool weather, they don't do much. Mushroom compost works fine as a soil medium but contains few nutrients. Peppers are heavy feeders, so to get plenty of foliage and fruit, you need to fertilize regularly. Try feeding your plants with some Miracle-Gro or Espoma Garden-tone.
5. Question: I received an ice cube orchid about two years ago that hasn't flowered since. What can I do to get it blooming again? —Marvell
Grumpy Says: Ice cube orchids sound like tiny ice sculptures but are really moth orchids watered by letting ice cubes melt atop the soil to "prevent overwatering." This is a dopey idea. First, moth orchids come from tropical Southeast Asia, where ice is foreign. Ice could damage the tender foliage and roots. Second, slowly dripping ice cubes don't water plants very well. A moth orchid needs the humidity provided when its bark soil is drenched with room temperature water that drains quickly and is reapplied once the soil dries. To get your orchid blooming, give it bright light and temperatures around 70 degrees. Twice a month, water the correct way and then feed with a liquid 20-20-20 fertilizer mixed to half strength.
6. Question: Recently, you told us how to water dried-out potting soil in containers. There was something about adding dish soap. I lost the article. Can you help me? —Martha
Grumpy Says: You lost one of Grumpy's articles? Outrageous! I can only pray that the Hope Diamond and the Mona Lisa are never put under your protection! However, in his kind mercy, Grumpy will supply you with this crucial information again. Add a couple of drops of liquid dish detergent to a quart of water. Slowly pour the water into the dry soil, stirring it with a stick or knife as you do. The dry potting soil will gradually absorb the water. Provided you do not allow the soil to dry out completely again, you should have no more problems.
7. Question: Tall gardenias are blocking my porch and windows. What is the best time of year to prune them back? —Heidi
Grumpy Says: Gardenias will be in bloom shortly, so wait to prune until they finish flowering. Then you can cut them back as far as you want. The cuttings are easy to root in water or moist soil.
8. Question: Black-and-yellow caterpillars have nearly defoliated quite a few of my shrubs. How can I prevent this from happening again? —Barbara
Grumpy Says: As soon as you see the first caterpillar, spray your plants according to label directions with one of three natural insecticides: Bacillus thuringiensis (DiPel, Thuricide), neem-oil, or spinosad. You can get these at your local garden center.
9. Question: My garden seems to attract wasps. Are there any plants that repel these bugs? —Mary
Grumpy Says: Wasps scare people, but they do have a good side: Some pollinate flowers just like bees do; and many are predators that buzz around your garden hunting for caterpillars, beetles, and other harmful bugs on plants. No plants that I know of repel wasps, so use wasp-and-hornet traps instead. Hang traps at least 20 feet away from human activity areas and known nests. Traps are available at home-and-garden centers and online at planetnatural.com.
10. Question: I have some very old azaleas that are about to hide my house! I know I should wait until after they bloom to prune. How far can I cut them back? —Doodle
Grumpy Says: I hope you're from Ohio, because that would make you a Yankee, Doodle. (Sorry, couldn't help myself.) Evergreen azaleas will sprout new foliage from bare stubs. So you can cut them back as far as you want. Prune before June.
11. Question: My rosemary plant has little webs on the stems, and the leaves are turning gray. Why? —Kathy
Grumpy Says: Webworms are the culprits. Cut out the infested stems; then spray the plant with neem-oil.
12. Question: What are some pretty, heat-loving plants that will do well in hanging baskets? —Christian
13. Question: Last summer, a neighbor gave me a beautiful mandevilla vine that curled around my mailbox. Now it is brown and dried up. Is there anything that I can do to bring it back? —Laura
Grumpy Says: Your mandevilla is toast. This semitropical vine cannot survive freezing weather outdoors. If you want to keep one from year to year in cold-winter areas, grow it in a pot you bring inside in fall, and keep it next to a bright window until spring.
14. Question: My spider flowers (cleomes) always get tall and gangly by late summer. Someone told me to cut them back by one-third in late June to make them bushier. Do you think that will work? —Barbara
Grumpy Says: That has never worked well for Grumpy. Instead of cutting back leggy spider flowers, I prefer to plant great dwarf selections such as 'Senorita Rosalita' (pink) or 'Senorita Blanca' (white). They'll grow only 2 to 3 feet tall, set no seed, and—best of all—produce blooms continuously.
15. Question: I have a pink crepe myrtle, but I want it to bloom white. Can I put down aluminum sulfate or something else on the soil to change the color? —Jane
Grumpy Says: Jane, Jane, Jane, the trick of changing flower colors by adding aluminum sulfate or lime to the soil works only with blue and pink (or red) hydrangeas. So you have only two options to get the color you want. Either buy a white crepe myrtle or paint the blooms. Grumpy hopes you choose the latter, so one of your neighbors will send him a photo of you doing it.
16. Question: We would like to grow a pomegranate bush. What conditions do they need? —Debra
Grumpy Says: Pomegranates are becoming popular because of their colorful, healthful fruit; brilliant yellow fall foliage; and showy red, orange, yellow, or white flowers. They need full sun and well-drained soil and do well in the Middle through Coastal South (USDA Zones 7 through 9). 'Wonderful,' a favorite selection for fruit, is used for POM Wonderful juice. (You can purchase 'Wonderful' plants online at willisorchards.com.)
17. Question: Our forsythia bush is a mess. There are runners everywhere, which would be fine for a hedge. We pruned it back drastically after it bloomed last year, but now you can't even tell. How radically can we cut it back without killing it? —Meg
Grumpy Says: Forsythia is one of those shrubs you really can't kill without using WMD—and the United Nations frowns on that. After it finishes blooming this spring, go all "black ops" on it and prune it nearly to the ground. It will grow back quickly and bloom fine the following spring.
18. Question: We have a huge Foster holly that has recently had lots of leaves turn yellow and drop. Is this normal? —Neal
Grumpy Says: Yep. Evergreen hollies maintain their foliage year-round, but individual leaves live only a year or two. Then they drop and are replaced.
19. Question: It gets so hot here in Dallas that tomatoes won't grow. Have any advice on tomatoes that can take the heat? —Bob
Grumpy Says: Yours is a common complaint throughout the lower half of the South. The problem isn't that the plants won't grow. It's that the flowers won't set fruit if it's too hot. What you need to do is plant heat-tolerant selections that don't mind Venus-like temps, such as 'Arkansas Traveler,' 'Solar Fire,' 'Heatwave,' 'Cherokee Purple,' and 'Sunmaster.'
20. Question: I plant various types of spring bulbs. They usually bloom the first spring but not after that. What am I doing wrong? —Candy
Grumpy Says: Their lack of longevity likely comes down to one of four reasons. 1) You cut off the bulbs' foliage before it turned yellow. 2) Squirrels, mice, and voles like to eat certain bulbs, such as tulips. 3) Bulbs planted in the shade will bloom the first year but not after that. 4) The bulbs you chose may not be suited to your climate.
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21. Question: Is there any new control for fire ants out there? The granules I was using didn't work well. —Brenda
Grumpy Says: I always said that if anyone came out with a natural, nonchemical fire ant control that sounded feasible, I'd let you know. Well, now there's Ant-Zap (available from amazon.com). It works by replacing the oxygen inside ant tunnels with carbon dioxide. The tiny ninjas and their evil queen suffocate in a few days. I haven't tested it yet, so don't hold your breath if you want a Grumpy guarantee. (FYI, there's a product called Mole-Zap too.)
22. Question: I have an elevated barrel composter that you spin to mix the contents. I'm worried that without ground contact, there won't be any earthworms inside. Do I need earthworms for composting? —Liza
Grumpy Says: Excellent question! If the compost is properly mixed, moisturized, and oxygenated, billions of microbes will do the composting. If they're working really fast, the compost will get too hot for earthworms. If not, add a shovelful of good topsoil from your garden. It will probably contain earthworm eggs. Then add some finished compost to each new batch.