Author: Maryland Grows

Root Crops in the Fall

Maryland Grows4 Comments
Radish, golden beets, and white turnip

If you’re seeing all kinds of lovely root vegetables at farmer’s markets this time of year, start planning now so you can grow them yourself next fall! I am so glad I decided to put in seeds for beets, turnips, and radishes back in August. These are all super-easy crops to grow, if you follow a few simple guidelines.

Here are the steps from thought to harvest:

  • Plan ahead! Buy your seeds for fall planting when you get the ones for spring and summer, because they may be hard to find later on. (Autumn root crops are usually grown from seed; buying plants is a waste of money since you only get one root per plant.) Radishes, beets, turnips, and carrots are all good choices.
  • Make space. Allowing room for fall crops can be difficult in a small garden. If some of your summer crops are not looking too great, take them out and prepare the bed for fall seeding. Or plant a bed with a summer cover crop or a quick-growing crop you know you’ll be removing soon, such as bush beans.
  • Prepare your soil. Root crops like a loose soil – try inserting a trowel into the soil, and if you have to force it in, you will not get a great root harvest. Add some compost! Raised beds provide the ideal environment, since the soil seldom gets compacted. Make sure your planting area gets plenty of sun.
  • Know how long your root crops will take to mature. It’s disappointing to not get edible roots because you didn’t allow enough time. Check HGIC’s planting guides for general information on timing, and also check the seed packet which will give you specifics for the variety you’re growing. Root crops are hardy and will tolerate frosts, so you can plan harvest for anytime from early October to late November, but the later you start the seeds, the slower the plants will grow. (This has more to do with the amount of sun than the temperature.) For a crop that lists 60 days to maturity from seeding, plant in mid-August (you’re allowing an extra week or two for the fall slowdown). Quicker crops like radishes can be planted in succession from late August to late September. Most root crops will sit in the ground just fine in cool weather, so you can harvest them as you need them.
  • Plant as directed. Don’t worry too much about spacing since you will be thinning later on.
  • Keep paying attention as the plants grow. Water regularly if it doesn’t rain, and take out weeds as soon as you can recognize which are the desirable plants. If your soil is low in phosphorus or potassium (which is unlikely), you may need to fertilize, but regular additions of compost through the year usually do the trick with these quick-growing crops. Thin the seedlings when they are several inches high – this means pulling out the plants in between a final set that are several inches apart. Think about what the roots will look like in maturity (what they look like when you buy them), and allow that much room plus a bit extra between plants. I find it easier to thin in two stages, taking out bunches when the plants are small and then a few more as they mature. You can eat the thinnings in salads, if you wish; they’re all edible and delicious.
  • Harvest when ready! All of these root crops will show some of the root portion above the soil, so you can check on size without pulling them out.

In practice, I’m often not on top of thinning, and it was hard to water enough this year with our persistent drought. So some of my root crops, especially the beets, are smaller than they should be. (On the other hand, some of the radishes are enormous.) But even with mistakes I manage to get good results! Try root crops next year and harvest some treasure from underground.

By Erica Smith, Montgomery County Master Gardener. Read more posts by Erica.

Little Beetles Are All Over My House!

Maryland Grows2 Comments

Q: What should I do about Asian beetles? There are hundreds of them on my house.

Multicolored Asian lady beetles (Harmonia axyridis) vary in color and the number of spots.
Photo: Gyorgy Csoka, Hungary Forest Research Institute, Bugwood.org

A:  There are multiple species of insects in our area that are native to Asia. The ones on your house are Multicolored Asian Lady Beetles (ladybugs). These beneficial insects are looking for a sheltered place to spend the winter. For this insect, or any other insect trying to enter on chilly nights, all you need to do is seal any gaps, cracks, or other access points. There is no effective repellent, and while the insects won’t harm people or damage the home itself, they can be a nuisance when they find their way in, since they are trying to find shelter for the winter. Check the window screening for tears that need to be repaired, and the door weather stripping for any gaps or worn-out pieces that require replacement.

By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun and Washington Gardener Magazine. Read more by Miri.

Have a plant or insect question? The University of Maryland Extension has answers! Send your questions and photos to Ask Extension. Our horticulturists are available to answer your questions online, year-round.

Q&A: Why Do My Boxwoods Look Off-Color?

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Boxwood leaves that are yellowish and blistered due to Boxwood Leafminer feeding.
Yellowing of boxwood leaves caused by Boxwood Leafminer feeding. Photo credit: Miri Talabac

Q:  I have a low hedge of boxwoods that are looking somewhat orange-tinted and less dense than usual. What might be causing this?

A: Boxwood Leafminer is my primary suspect, and I have recently seen boxwoods looking just like you describe, which had high populations of this common insect pest.

With only one generation per year, this species of fly is currently in its larval (juvenile) stage inside the leaves. Since larvae feed on tissues between the upper and lower leaf layers, you need to peel the leaf apart to find them to confirm their presence. Outwardly, affected leaves will become blistered-looking and have a blotchy yellow or orange-yellow color. Leafminer damage can also cause the shrubs to shed some leaves prematurely, so the branches will have more sparse growth towards the plant’s interior than a healthy shrub would have.

Boxwood Leafminer larvae are tiny orange-yellow legless maggots, only a few millimeters long. However, they are readily visible if you open a leaf and examine it with a hand lens, since the rest of the leaf interior will be light green. They will pause feeding as winter approaches and overwinter in a state of suspended development, resuming more voracious feeding in early spring. Larvae pupate and transform into orange gnat-like adults by late April or early May (depending on temperature trends).

Boxwood leaf tissue has been cut away to reveal Boxwood Leafminer larvae feeding between the upper and lower leaf surfaces. Photo credit: John Davidson, Ph.D., UMD

Some boxwood cultivars have greater resistance to leafminer (as well as to fungal diseases) than others. When the insects are too abundant for their damage to be tolerable, prune out the infested branch tips or, as a last resort, consider using an insecticide to reduce their numbers. Keep in mind, though, that insecticide use can have unintended consequences: it might facilitate an increase in boxwood spider mites (by killing mite predators); harm pollinators visiting the boxwood’s flowers; or harm insect or spider predators wandering its foliage that would be eating pests.

You can learn more about leafminer as well as other common boxwood ailments on Extension’s boxwood diagnostic web page (go.umd.edu/boxwood]).

By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun and Washington Gardener Magazine. Read more by Miri.

Have a plant or insect question? The University of Maryland Extension has answers! Send your questions and photos to Ask Extension. Our horticulturists are available to answer your questions online, year-round.

Meet the “Earth Almond,” aka Yellow Nutsedge

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You may have suddenly noticed yellow nutsedge (Cyperus esculentus) crowding into your mulched garden beds or lawn in late summer/early fall. Also known as “chufa sedge, tiger nut, or earth almond,” this charismatic and fascinating plant was one of humanity’s earliest cultivated plants. It is still cultivated and considered a culinary treat in North and West Africa, western Europe, and China for its nutritious nut-like tubers attached to underground stems known as “rhizomes.” 

Yellow Nutsedge (Cyperus esculentus) can quickly colonize bare spots in a mulched planting bed. Photo credit: Stacy Small-Lorenz | UMD

Yellow nutsedge can be identified by its yellowish coloration, stiff triangular stem, and three long leaf bracts at the base of a puffy brown flower. It tends to thrive in sunny areas with moist, disturbed soils.  While similar in appearance to straw-colored flatsedge (Cyperus strigosus), it can be distinguished by its small, nut-like tubers. One yellow nutsedge plant can produce thousands of tubers, which allows it to produce more vegetation in the spring. Yellow nutsedge flowers in late summer and early fall and is a wind-pollinated plant that cannot self-pollinate.

Yellow Nutsedge (Cyperus esculentus) tubers and rhizomes. Tubers distinguish it from 
Straw-colored Flatsedge (Cyperus strigosus). Photo credit: Stacy Small-Lorenz | UMD

Yellow nutsedge colonized North America before Europeans did, so it is considered native here by some sources. In Maryland, it is most abundant in the Piedmont and Coastal Plain ecoregions.  It is often treated as an aggressive agricultural and lawn weed across the U.S. because it can quickly take over disturbed areas and may outcompete lawn or garden plants. It tends to thrive in mulched beds and lawns that are overwatered or mowed too short.

To remove yellow nutsedge manually, you’ll have more success starting early in the season, when the plants have fewer than five small leaves. If you’re pulling in late summer or early fall, once flowers have developed, you might leave tubers and rhizomes behind in the soil that will only multiply. So, if you’re trying to manage its spread, try to remove as much of the underground plant material as possible, then stay on top of pulling it early when it emerges again next summer. You might also consider re-planting the area densely with a variety of native plants suited for sunny, moist conditions, then stay on top of weeding in spring.

If you choose to make peace with yellow nutsedge as part of your landscape, however, you can take comfort in knowing that its large underground biomass contributes organic matter and aeration to clay soils, improving water infiltration and soil structure for enhanced plant growth. It also makes a greater contribution to biodiversity than turfgrass – it’s a food source for Wild Turkeys and a wide variety of mammals that root up the tubers, and it is noted by the Maryland Biodiversity Project to be a larval host plant for the Dun Skipper (Euphyes vestris).

The Dun Skipper (Euphyes vestris) uses Yellow Nutsedge as its larval host plant.
Photo Credit: Katie Woods | iNaturalist CC BY-NC

By Stacy Small-Lorenz, Ph.D., Residential Landscape Ecology Specialist, University of Maryland Extension. Read more posts by Stacy.

Itchy, Witchy, Hexing, Vexing Plants

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Scary plants earn Halloween points. Some plants are downright scary. Since Halloween is around the corner, I thought it might be fun to discuss a few. 

Raise your hand if you love weeds.  Okay, weeds are my nemesis. Yours too, I bet. If you’ve ever wrangled with mile-a-minute you’ve probably dreamed of this vine engulfing your house, your car, your dog.  Ditto with bindweed, bermudagrass, and other brats. But armed with a little knowledge and persistence, you can get the upper hand.  There’s a good weed ID guide on our website with photos and management tips. 

Mile-a-minute vine with blue berries.
Mile-a-minute weed spreads aggressively by seeds spread by birds. Photo credit:
Leslie Mehrhoff, University of Connecticut; Bugwood.org

Much scarier are invasive plants.  These plants are obnoxious spreaders that threaten ecosystems. English ivy, garlic mustard, and others bully out native plants that we – and wildlife – need. Lest you think I’m exaggerating, look at photos of garlic mustard blanketing forest floors or trees smothered in English ivy.  These plants are a serious threat and need to be banished.  Learn more at our invasive plants page.

Garlic mustard plants with white blooms growing beneath pine trees.
Garlic mustard sneaking under a pine tree.
English ivy vines growing up on and covering forest trees.
An infestation of English ivy in a forest. Photo credit: Leslie Mehrhoff, University of Connecticut; Bugwood.org

Have you ever noticed a garden center plant labeled as “vigorous?”  Beware.  That could be nursery-speak for “spreads like wildfire.”  These vigorous plants are often beautiful and can be tamed, but it’s best to go into any relationship informed.  I call them my beautiful monsters, plants I can’t be without but need to manage carefully.

Mint will spread like mad so always, always contain it in a pot.  Brazilian verbena (Verbena bonariensis) will drop seed like crazy.  Deadhead it – or at least some of it – before it goes to seed. Obedient plant (Physostegia virginiana) is anything but obedient.  Dig out its sneaky underground rhizomes where you don’t want it or enjoy it in others’ gardens.  Yes, it’s a native, but it is a serious spreader.  Forewarned is forearmed.

Obedient plant with purple flowers.
Obedient plant is anything but obedient, spreading quickly. 

Another scary plant is poison ivy.  I itch at the mention of its name.  The merest brush of a leaf is enough to make me blister. First things first when tackling poison ivy.  Cover any part of you that might come into contact with the plant.  And consider having on hand a product that neutralizes the oils that cause itching. Remove small seedlings by hand.  Sever vines growing up trees.  Treat when you must, following the guidelines in our fact sheet. Ironically, we’re the only species for whom poison ivy is a problem.  It’s a native plant with berries that form late to feed many forms of wildlife. It only irritates our skin and sensibilities.

Poison ivy vine growing up a tree trunk.
Poison ivy deserves respect…and distance. Phot credit:
Betty Marose

Less scary are the plants in our gardens with a white latex sap such as milkweed, balloon flower (Platycodon grandifloras), and spurge (Euphorbia species).  The sap can cause minor skin irritations, more of an annoyance than a threat. The same is true with juniper rash, the red dots you get from pruning junipers.  Wear gloves to protect your hands from itchy spots and dots.

I hope I haven’t scared you too much.  Most plants are quite harmless and a delight to both tend and behold.  Into every garden a few itches, weed witches and vexing plants must grow. 

By Annette Cormany, Principal Agent Associate and Master Gardener Coordinator, Washington County, University of Maryland Extension.  Read more by Annette.

Leave (Some of) Your Leaves

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Don’t feel guilty about being a little lazy this fall! Trying to remove every single leaf that lands in your yard is a lot of effort, without all of the reward.

Many municipalities will encourage leaf collection, sometimes distributing collection bags or vacuuming leaf piles from the street. The goal is to prevent leaves from making their way into our stormwater systems, where clogs could lead to flooding in the case of a large rain event. It is therefore important to follow local ordinances to relocate leaves in front and side yards that border a road. However, fallen leaves are valuable resources containing essential nutrients, and you may consider keeping some of this ruby and gold treasure for yourself!

Autumn leaves in reds, oranges, and yellows are beneficial as well as beautiful. Credit: Wikimedia Commons.

Here are some ideas for sustainably managing leaves in back yards and other areas where leaves are unlikely to be washed down a storm drain:

  • Move leaves onto garden and flower beds. You wouldn’t want to leave a thick mat of leaves on your lawn—it would kill the grass beneath; for that same reason, leaf cover is an excellent substitute anywhere you might put mulch. A layer of leaves (aim for at least two inches) will suppress weed growth in overwintering vegetable gardens, perennial flower beds, and around decorative shrubs. To stop the leaves from blowing away, wet them with a hose or watering can. These leaves will decompose slowly, releasing micronutrients back to the soil over time, retaining soil moisture, and helping your plants grow in the spring.
  • If you have more leaves than needed for your landscaping beds, simply mow over them where they fall. Mowing will break leaves down into smaller pieces, both preventing the thick cover that would smother your grass and speeding up the decomposition process. The additional organic matter will benefit your lawn. 
  • Select a sheltered spot in your yard to leave fallen leaves intact. Insects need protection from the winter chill if they are to survive to the spring, and fallen leaves are excellent habitat! They insulate beneficial insects amidst the litter and in the soil below. Don’t mow the leaves in this sheltered spot, or you’ll shred the hibernating insects, too!
Ladybugs need warm, protected spots like leaf piles to survive the winter; as avid aphid-eaters, you’ll be glad to have them in your garden come summer. Credit: PickPik.
  • If you have a backyard composting system, fallen leaves are a great addition! The ideal compost mixture contains a combination of “greens” and “browns” (nitrogen-rich and carbon-rich materials, respectively). Dry leaves are considered “browns.” Crumbling them first will speed up the process.

Whatever options you choose, I highly recommend using rakes or at least electric mowers/leaf blowers over gasoline-powered yard tools, which are noisier and emit pollutants including carbon dioxide, methane, benzene, and other toxic and carcinogenic compounds that harm both human and environmental health. Now, I’ll ‘leaf’ you to it!

Manual yard tools like rakes are a more environmentally-friendly way to move leaves than gas-powered leaf blowers. Credit: Elenathewise, Getty Images.

By Sarah Rothman, Postdoctoral Fellow and Adjunct Faculty in the Department of Environmental Science and Technology at the University of Maryland. Read more by Sarah.

Q&A: Why Are My Plants Turning Black?

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Sooth mold fungus appearing as black splotches on the narrow leaves of a variegated sedge plant.
Sooty mold covering a variegated sedge (Carex). Photo credit:  Miri Talabac

Q:  Why are several perennials in my garden bed turning black? Can they all be affected by the same disease?

A:  Most plant diseases are not that wide-ranging, but in this case, the black residue is not an infection. It is a fungal species, but this fungus does not cause plant disease, as it only grows on the surface. Named for its black color, sooty mold is a group of fungi that feeds on the sugars in honeydew. Honeydew is a waste secretion produced by sap-sucking insects, such as aphids, leafhoppers, soft scales, and planthoppers (which includes Spotted Lanternfly).

The numerous questions that UMD Extension receives each year about sooty mold often result from the presence of Crapemyrtle Bark Scale and Spotted Lanternfly. At this time of year, a heavy buildup of sooty mold from high populations of high-bark scale or lanternflies can be a prominent eyesore. Reduced rainfall that isn’t diluting or rinsing away the honeydew contributes to the problem, but it’s also due to increased insect feeding. (The juvenile lanternflies present earlier in the year don’t generate as much honeydew.)

Sooty mold wears off on its own over time. If the insects generating the honeydew are suppressed (which is not always necessary from a plant health standpoint), it deprives the sooty mold of its food source. If you want to try removing the residue, look for products with a horticultural oil active ingredient, which include specific directions for sooty mold treatment on the label. The spray may make the mold easier to dislodge several days later using a strong spray of plain water from a garden hose.

By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun and Washington Gardener Magazine. Read more by Miri.

Have a plant or insect question? The University of Maryland Extension has answers! Send your questions and photos to Ask Extension. Our horticulturists are available to answer your questions online, year-round.