February 2023 – Maryland Grows

Plant shopping soon? Avoid buying invasive plants

February 28, 2023March 7, 2023Maryland Grows4 Comments

It’s a sunny day in late February and that means I’m looking at seed catalogs and dreaming of new plants! Have you been plant shopping yet this year? Adding new plants and seeds to your garden creates new scents, textures, colors, and shapes and is the easiest way to increase biodiversity in your landscape!

As you begin revitalizing your garden space this spring, I want to bring some attention to invasive plants, a category of plants that should strike fear and dread in your heart! Okay, maybe that’s a bit dramatic, but truly this is a topic that everyone needs to learn more about.

Q. What is an invasive plant?

A. An invasive plant is a non-native, “alien” species that was introduced intentionally or by accident into the landscape and causes ecological and/or economic harm. These plants tend to be free from predators, parasites, and diseases that could help keep them in check. These plants reproduce rapidly with multiple methods (i.e. seeds, stolons, root cuttings, runners, etc.) and spread aggressively. They tend to be deer resistant or deer tolerant, a big reason why they are purchased and planted in landscapes. Below is a photo of purple loosestrife. Notice how it is creating a monoculture, a visual key that might mean the plant is “invasive.”

purple loosestrife flowers crowding a field — Invasive purple loosestrife (*Lythrum salicaria*).
Photo: Richard Gardner, Bugwood.org

Did you know that some invasives are still for sale at nurseries, greenhouses, and in mail-order catalogs?

It’s true. Many of the plants on “watch lists” are still readily available to purchase. Japanese barberry is an invasive plant that is a very popular landscape plant still being widely planted today; however, research shows that black legged ticks have been found in areas with invasive barberry thickets because these non-native, invasive forest shrub thickets create ideal microclimates.

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Look out for wintercreeper

February 22, 2023February 22, 2023Maryland Grows5 Comments

wintercreeper vines climbing up trees in a forested area — Wintercreeper euonymus (*Euonymus fortunei*) overrunning a woodland floor and climbing tree trunks. Photo: Ryan Armbrust, Kansas Forest Service, Bugwood.org.

Q: I realize English ivy is widespread in Maryland, but there are some evergreen vines clinging to trunks that look a bit different than typical ivy leaves. Are they native, or should they too be removed?

A: An evergreen climber I see covering tree trunks in parks which might be confused for English ivy at a distance is wintercreeper (sometimes written winter creeper; Euonymus fortunei). This non-native invasive acts like English ivy in that it’s a groundcover when no support to climb is present, and a clinging vine when trunks or walls are available.

wintercreeper vine — Wintercreeper vine. Photo: Chris Evans, University of Illinois, Bugwood.org

wintercreeper flowers — Wintercreeper vine. Photo: Chris Evans, University of Illinois, Bugwood.org

This species also has negative impacts on the trees and our ecosystem and should be removed if growing on your own property. Parks manage invasives as best they can, but with limited resources, we can do our part by not cultivating the species likely to spread into them, even if we don’t live immediately next to parklands. Weed Warrior volunteer programs exist, such as in Montgomery County, if you wish to be trained in invasive plant ID and to help with their removal on public lands. While wintercreeper has been banned for sale by the Maryland Department of Agriculture since 2018 as a Tier 1 invasive plant, established plants in the region can still mature enough to produce fruit (berries) that wildlife then inadvertently spreads into natural areas. Long a popular landscaping groundcover due to those vibrantly green leaves (and the variegated forms for their color), I always recommend removal and replacement with alternatives, preferably a medley of native species instead.

As with English ivy, it’s safest for the tree to simply sever the climbing wintercreeper stems’ connection with the roots in the ground and let them slough off the trunk on their own as they dry out and disintegrate. Even though they attach via root-like structures, those aren’t functional roots and no moisture or nutrients are absorbed by them. Pull up, smother (deny them light), or spray any running stems covering the ground. As with any tenacious weed, eradicating an established patch of this species may take time and repeated efforts at removal before finally being successful. Be vigilant, because birds could always re-introduce it in a future year. (Invasive plants…the gift that keeps on giving.)

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.

Invite spring indoors with forced flowering branches

February 15, 2023July 17, 2023Maryland GrowsLeave a comment

Cherry branches are ideal for forcing into bloom indoors.

If the muted greys and browns of winter have you down, beat the blues by forcing some cut branches into flower.

It’s easy, gets you outside, decorates your home, and gives you the pleasure of watching buds open and flowers unfurl.

All you need is a sharp pair of hand pruners and some spring-flowering tree and shrub branches to cut and bring indoors.

Fortunately, this is a great time to prune most deciduous trees and shrubs, so this is a twofer. You’re pruning your plants and gathering branches to force into bloom.

Branches are ripe for harvest in February. Plants have had the six weeks of dormancy they need and are starting to plump their buds in anticipation of spring.

And no, you’re not harming these trees and shrubs by cutting them. You’re just nudging their branches into flower a few weeks earlier.

Cut branches on a milder day when the buds are softer and better able to make the transition to warmer indoor temperatures.

Snip branches one- to two-feet long for forcing. Branches pencil-thick or thinner are best.

Look for branches loaded with flower buds. These are the fat, round ones. Leaf buds are smaller and pointed. When in doubt, slice a bud open. Do you see tiny leaves or flower parts?

Sorry, I couldn’t resist sneaking in a botany lesson.

As you’re cutting, remember your pruning basics. Make sharp cuts at an angle so water runs away from the cut. Prune out crossed branches or ones that grow inward.

Thin dense areas for air circulation. And step back often to make sure you’re creating a good shape and not cutting away more than a third of the plant.

Gather the branches you’ve cut and bring them inside. Recut the stems and put them in a bucket of warm water in a cooler room. Let them drink overnight, then arrange them in vases.

Some experts cut stems underwater, add floral preservative, or put stems directly into vases. Regardless of your technique, change the water at least weekly to keep bacteria at bay.

Place your finished design away from fireplaces and other heat sources. To mimic spring’s temperatures, display your branches in a cooler room out of direct sunlight.

But certainly, put some of your branches somewhere where you can have the pleasure of watching the buds pop open to reveal their spirit-lifting blooms.

Did I say blooms? You need not limit yourself to bold flowers. Pussy willows and other plants that form catkins – fuzzy or thin, dangling clusters of tiny flowers – look wonderful indoors.

Cut branches of pussy willow. Photo: C. Carignan

Is it possible to walk by a vase of furry pussy willow catkins and not pet them? I think not.

Some spring-blooming trees and shrubs that force well are cherry, forsythia, redbud, quince, serviceberry, red maple, witch hazel, magnolia, crabapple, pear, and plum.

For catkins, take cuttings from beech, birch, filbert, and willow. If you want a longer show, cut branches every few weeks.

Make spring come early. Gather branches for forcing and enjoy the show.

By Annette Cormany, Principal Agent Associate and Master Gardener Coordinator, Washington County, University of Maryland Extension. This article was previously published by Herald-Mail Media. Read more by Annette.

Lawn Alternatives for Shady Yards

February 9, 2023May 22, 2024Maryland Grows3 Comments

Although a non-native example, this New Zealand Hair Sedge (*Carex comans*) illustrates the soft, flowing look multiple sedge species provide. Photo: M. Talabac

Q: I’m happy to try a lawn alternative for my shadier areas but I’d like it to look more like a lawn than a groundcover or mix of flowering plants. What kind of grasses work for that?

A: Not many true grasses will grow well if you have less than full sun, but several perennials that look like grasses can work nicely. My primary recommendation would be to try one or more species of sedge (Carex). I was excited to see the study results for sedges from Mt. Cuba released recently: “Carex for the Mid-Atlantic Region” that may be a useful reference.

Mt. Cuba Center is a public garden and research facility in Delaware which displays and studies native plants, and they perform periodic plant trials to evaluate species and cultivars for garden performance. Lately they have been including an assessment of pollinator appeal as well, though in this particular case that wouldn’t apply since sedges are not grown for pollinator draw. (Even though the caterpillars of several of our less-often-seen butterflies feed on sedges.)

Sedges are a species-diverse group and make for an excellent grass-like aesthetic in partial shade to full shade. Many form low soft-looking tuffets, though with time or dense planting can form a more-or-less uniform “lawn.” Still, don’t expose them to much foot traffic since nothing is quite as tolerant to that as turfgrass. Well over one hundred sedges are native in Maryland, and the Mt. Cuba study results include lists of those well-suited to more sun than shade, more shade than sun, and a tolerance to mowing (not that they require it by any means).

A few true native grass species tolerate some shade, but won’t give you a comparable look to a lawn since they grow much taller or have a different leaf color or texture (often wider, coarser leaves). Examples include river oats (Chasmanthium latifolium) and Eastern bottlebrush grass (Elymus hystrix), which still could make nice accents if you wanted spots with showier seed heads.

The non-native asparagus relative mondo grass (Ophiopogon), which has dark green grassy evergreen leaves and a slowly-spreading growth habit, has been successfully grown as a lawn look-alike under mature trees. I would not recommend using its cousin Liriope, the spreading form of which (Liriope spicata) can be too aggressive and is considered invasive. (Plus, it’s way over-planted.) Mondo grass thus far does not appear to be colonizing natural areas in or near Maryland.

Beyond Broccoli: A Brassica Series

February 3, 2023July 24, 2023Maryland Grows5 Comments

*Broccoli photo from University of Maryland Extension*

Welcome to “Beyond Broccoli”! In my next several monthly posts, I’m taking a deep dive into the genus Brassica and its place in our vegetable gardens. In this first installment, I’ll be exploring the classification of these plants and where they fit into the plant world.

Brassica is (logically enough) part of the family Brassicaceae, which is pretty huge, containing approximately 372 genera and 4060 species. Most of these are not common garden plants, though plenty are; examples include sweet alyssum (Lobularia maritima), honesty (Lunaria annua), and stock or gillyflower (Matthiola incana). Other notable plants in this family include Arabidopsis thaliana or thale cress, used as a model organism in many scientific studies, and Allilaria petiolata or garlic mustard, a persistent weed many of us fight back for years. One way to get rid of your garlic mustard is to eat it—it’s strong-tasting but great to mix with other greens. Many Brassicaceae plants are edible, though of course not all; always investigate before ingesting.