Grumpy Answers Your September Gardening Questions
The not-quite-fall month keeps gardeners on their toes.
1. This fall, I'm going to lift and divide my 100-plus daffodils. I would like to plant perennials over them—nothing too fancy, as I'm an inexperienced gardener. This area is well drained with morning sun and afternoon shade. Suggestions? —Bonita
Grumpy Says: Bonita is such a pretty name! (I wonder what it means in Spanish?) I recommend you plant daylilies over your bulbs. They're tough and easy to grow and come in lots of colors—so they're perfect for beginners. In spring, their emerging foliage will hide the fading daffodil leaves.
2. There is a huge rock in the ground a few inches below the surface where I want to plant a Black Diamond series crepe myrtle. The roots would all have to grow sideways. Would this be feasible? —The 439
Grumpy Says: "The 439." Let me guess. Your senior class had 439 people, and that was your class rank? (Just kidding. Grumpy was mean.) Planting where you propose means very little soil for the roots to grow in. As a result, the tree will be very prone to water stress during hot, dry weather and might topple in high winds. Unless you can plant with a jackhammer, this sounds like a rather dubious project.
3. I transplanted a butterfly bush last week, and now all the leaves and blossoms are drooping. Will it survive? —Madison
Grumpy Says: Your shrub is suffering from transplanting shock as a result of being moved during warm weather. I suggest you cut it back by half now to reduce water loss from the leaves. Keep the shrub well watered. It should recover, but I wouldn't bet the mortgage on it. Next time, wait until October or November to transplant.
4. I planted two big whiskey barrels with flowers, but the soil in them seems to stay too wet and compacted (bright yellow mushrooms gave that away). Is there something I can do to improve the drainage? Can you recommend any pretty, fall-flowering plants for growing in my whiskey barrels in USDA Zone 9? —Bridget
Grumpy Says: To improve drainage, start by replacing the dirt with brand-name potting soil (not topsoil or anything else). Next, make sure the drainage holes aren't clogged. Finally, raise the barrels an inch or so off the ground using terra-cotta "pot feet." For flowers, I recommend planting mums, pansies, violas, calendulas, dianthus, snapdragons, nasturtiums, and petunias.
5. I have a healthy and bushy French hydrangea that hasn't flowered in four years. It gets a lot of sun. How do I make it bloom again? —Lela
Grumpy Says: Have you been pruning it in fall or winter? Unless you have a reblooming French hydrangea (Hydrangea macrophylla), pruning it during these seasons means cutting off flower buds that would open the following summer. Stop pruning yours for a year (it won't die–I promise), and see if that makes a difference.
6. I planted a flowering cherry this spring. Some of the leaves are yellow with brown splotches. Others are dry, brown, and dead. What should I do? I have a brown thumb, and I should know better than to grow anything other than a peace lily or spider plant. —Sherry
Grumpy Says: Sherry, that tree sounds positively terminal. This could be due to several factors but none that you can really address at this point. Wait to see if it leafs out in spring and if there is any dieback. If the tree still looks sickly, you should probably replace it.
7. When my son cuts the grass, he leaves clumps all over the yard, and it looks terrible. My neighbors are ready to run me off the block. What is he doing wrong? —D.T.
Grumpy Says: Don't be so hard on the guy. Many people have sons who just hang out in the man cave all day texting and playing video games—at least yours cuts the grass (albeit badly). The reason for the clumps is either the grass is getting too high between cuttings or he's cutting it when it's wet. Explain this to him. You'll need to send him a text.
8. I may be the only gardener ever to go the entire season without a single zucchini! The plants bloomed and there were plenty of bees to pollinate them, but no squash formed. Please help! —Irene
Grumpy Says: You are not alone. The same thing happened to Grumpy this year. Only female flowers form fruit, but my plants produced nothing but male ones. Outrageous! Unfortunately, there isn't anything you can do about this but hope for better luck next year.
9. Is September a safe time to divide daylilies? —Charlotte
Grumpy Says: Yes, and it's an easy job too. Just use a garden fork to lift a clump from the ground. Shake off the soil, and pull apart the clump into smaller ones. Replant them, and then water. Other perennials that are good to divide now include iris, bee balm, black-eyed Susan, summer phlox, and hostas. Wahoo! Free plants!
10. I have a very small area (5 by 10 feet) at the entrance to my driveway where I would like to plant a small, low-maintenance tree. Suggestions? —Dale
Grumpy Says: My first choice would be a weeping Japanese maple such as "Crimson Queen" or "Garnet." Their leaves are red in spring, burgundy in summer, and scarlet in autumn. "Ruby Falls" weeping redbud is another good pick. It combines deep lavender spring blooms with maroon leaves. Or plant a compact crepe myrtle, such as one from the Early Bird series.
11. I bought seeds of many different perennials not too long ago. Is it too late in the year to plant them? —Tamara
Grumpy Says: You can sow them outdoors now. They'll germinate in spring. Or you can leave them in their seed packets in a cool, dry place and sow them in spring. Be patient either way—blooming may take a few years.
12. We have goatheads sprouting in our lawn this summer! What can we do to get rid of them? —Carrol
Grumpy Says: There is nothing more unnerving to the average homeowner than seeing goatheads pop up in the yard. Despite their grisly common name, "goatheads" aren't ruminant zombies but creeping annual weeds also known as puncturevines. They spread their seeds by using spiny burs that stick to people's clothing and the fur of passing animals. The spines are so stout that they're said to be able to puncture bicycle tires. To kill goatheads that are already growing, spray them according to label directions with Ortho Weed B Gon. Early next spring, apply a lawn weed preventer that's labeled for broadleaf weeds to keep goathead seeds from germinating.
13. I carried a rhubarb plant from Minnesota to our home in Austin, Texas. Will rhubarb grow here? —Carrol
Grumpy Says: Congrats, Carrol, on being the first reader to get TWO questions answered in one column! Your neighbors ought to anoint you with precious oils. Rhubarb dislikes long, hot summers and short, mild winters, so the best place to grow it in our region is the Upper South (USDA Zone 6), where it is a perennial. Austin, however, sits in the Lower South (USDA Zone 8), where rhubarb is a cool-weather annual. Set out divisions in fall, and harvest in winter and spring. "Victoria" is the preferred selection for growing this way.
14. What does Grumpy think of wax myrtle for use as a screening plant? —Ann
Grumpy Says: Grumpy gives it two thumbs up! Wax myrtle (Morella cerifera) grows fast in just about any soil, takes trimming well, has no serious pests, and is evergreen.
15. How do you kill weeds with vinegar? —June
Grumpy Says: Some organic gardeners tout horticultural vinegar (20% acetic acid) as a natural herbicidal alternative to Roundup. But Grumpy does not. For one thing, vinegar this strong is very caustic and can cause serious damage to skin and eyes. Like Roundup, it isn't selective—it damages all plants it touches. Unlike Roundup, it isn't taken down to the roots, so tough perennial weeds may grow back. And it strongly acidifies the soil, which some plants might not like. Its best use is for killing weeds in the cracks of sidewalks and driveways, but beware: Repeated use can actually dissolve concrete.
WATCH: 5 Awful Weeds with the Grumpy Gardener
16. The leaves of my poor gardenias are turning black! I tried rubbing it off, but a lot remains. What should I do? —Sheri
Grumpy Says: Your gardenias are under attack from sucking insects. These bugs secrete a sticky honeydew that feeds black mold. Get rid of the bugs and you'll get rid of the mold. To do this, either spray your plants with horticultural oil or apply Bayer Advanced Tree & Shrub Protect & Feed.
17. Mint has totally been running rampant in our garden, engulfing hostas, daylilies, verbenas, yarrows, and black-eyed Susans. We have already tried pulling up huge sections, but it just bounces right back. Do we need to completely clear the garden to de-mint it, or would that just be demented? We'll sip some mint tea while we're waiting for your answer. —Bryan
Grumpy Says: You have made two serious mistakes, Bryan. First, you're wasting fresh mint on tea, when you should be using it for mint juleps and Mojitos. So disappointing. Second, you should never, ever plant mint in a garden with other plants or it will spread faster than fleas at a flophouse. Grow it only in pots or in confined beds by itself. To eradicate this hellacious herb, dig up all your good plants this fall, remove any traces of mint, and store the plants in pots. Then spray the entire bed with a broadleaf weedkiller. Replant when you're sure the mint is dead. Some sprigs of mint you missed will undoubtedly sprout next spring. Quickly pull them up.
18. We are building a new home and have dug up lots of clay. What are some plants that will grow in clay soil? —Bonnie
Grumpy Says: Here goes: nandina, loropetalum, holly, pyracantha, quince, juniper, Indian hawthorn, wax myrtle, spiraea, forsythia, yucca, bearded iris, crinum lily, daylily, sedum, redbud, ginkgo, crepe myrtle, and chaste tree. Oh, and a bottle tree too.
19. I'm looking for a short, evergreen, ornamental grass that takes the heat. Can you help? —Lisa
Grumpy Says: Can Gordon Ramsay scream? Try a selection of blue fescue (Festuca glauca) called 'Elijah Blue.' It forms a mound of bright blue leaves about 8 inches tall.
20. Can oleander stay indoors all year? The guy at the home-and-garden center says yes. —Connie
Grumpy Says: Not unless you live in a greenhouse. (They need full sun in warm months.) Do bring it inside to a cool, well-lit room for winter if temps drop to 15 degrees or below. Take it outside after your last spring frost. You can grow it this way for decades. Grumpy's potted oleander is more than 30 years old and recently received a membership invitation from AARP.
21. How can I get rid of the armadillos that are tearing up my yard? —Nancy
Grumpy Says: Well, you could trap them (thearmadillotrap.com), repel them (liquidfence.com/armadillo-repellents), or grab your trusty .22 and bring home dinner! Grumpy was delighted to find a recipe for Texas Armadillo at cdkitchen.com that includes white wine, thyme, garlic, rosemary, onion, brown mustard, and light cream. Woooo-eeee, does that sound good! If your guests should question the meal set before them, just announce it's "Possum on the Half Shell." Serve with a spicy Rhône red or perhaps an Australian Shiraz. Bon appétit!
22. My daffodils haven't bloomed in two years. I plan to dig them up and move them. Do you think they'll bloom again? —Claudia
Grumpy Says: There's no way to be certain, but start by giving them the conditions they like when you transplant. Plant the bulbs 4 to 6 inches deep and 6 inches apart in well-drained soil where they'll get plenty of sun. Add 1½ teaspoons of Espoma Organic Bulb-tone 3-5-3 fertilizer to each hole when planting.
23. A vole chewed off my oakleaf hydrangea and left only a little bit with roots. I want to save it. Should I move it this fall to an area that has lots of vole-eating black snakes? —Catherine
Grumpy Says: Wow—Grumpy's first snake-loving reader! How thoughtful of you to provide sustenance for these lovable, friendly serpents. Go right ahead. Another thing to try is removing any mulch or leaf litter from around the base of the shrub. (Sneaky voles like to hide under it when they are feeding. Grateful snakes will still find them, though.)
24. Is there a way to get my 'Knock Out' roses to look good after this hot summer? How and when should I prune them? —Marilyn
Grumpy Says: Even a 'Knock Out' looks woozy after months of Southern heat. So put on some leather gloves to protect you from its vicious thorns and then use hand pruners to cut the plants back by about one-third. Next, fertilize them according to label directions with Miracle-Gro Water Soluble Rose Plant Food. As soon as the weather cools and you get some rain, your 'Knock Out' roses will live up to their name, sending out fresh foliage and blooming for the rest of fall.
25. I'm growing 'Juliet' and 'Sweet 100' tomatoes. They've been very prolific to this point, but after the heavy rain we've had, the ripening fruits burst open like in the movie Alien. What's causing this? —John
Grumpy Says: When it rains a lot over a short period, tomato plants pump a lot of water into the ripening fruits. But tomato skins can't grow fast enough—they split open and people faint. Fortunately, the effect is temporary, so you won't have to blow up your ship to save Earth like Ripley did in the movie.
26. I planted two possumhaw trees in hopes of having red berries at Christmas. No berries. Any ideas? —Dolly
Grumpy Says: You need both a male and a female plant. You have either two males or two females. You can tell boy from girl when they flower in spring: Male flowers have yellow pollen, while females have tiny, green pistils in the center. If you need a male, just buy one, as it doesn't offer berries, only pollen.