How will climate change affect native plants?

Maryland Grows3 Comments

Maryland temperatures are predicted to increase 5⁰ F to 11⁰ F by 2100. Higher temperatures will cause native plants to experience more heat-related stress, a situation that will be made worse by longer droughts. Warmer temperatures will cause earlier leaf out and bloom times, de-synchronizing relationships between plants and their pollinators. Invasive plants will become even more aggressive because higher atmospheric carbon dioxide (CO2) levels preferentially promote the growth of invasive plants.

Graph from NOAAs Maryland Climate Summary
Graph from NOAAs Maryland Climate Summary

Some species will adapt to the changing climate, allowing them to maintain or even expand their natural ranges. Native species that still thrive in your region, for example, have adapted to all the climate change that has occurred so far. City native plants have also adapted to all the warming associated with the urban heat island effect, and they have done so in just a few decades.

This common milkweed is thriving in a Washington D.C. hellstrip. This species’ ability to conquer the urban heat island suggests it can tolerate some climate warming. In fact, herbarium studies show that common milkweed is expanding its natural range southward despite climate change.
This common milkweed is thriving in a Washington D.C. hellstrip. This species’ ability to conquer the urban heat island suggests it can tolerate some climate warming. In fact, herbarium studies show that common milkweed is expanding its natural range southward despite climate change.

As the climate warms, the temperature conditions with which a species co-evolved will move north or to higher elevations. But plants can’t just get up and migrate the way some animals do. Plants migrate through seed dispersal. For northward migration to work there must be large, contiguous blocks of natural area. Species that are adapted to life on Maryland mountaintops are in peril because there are no higher elevations to migrate to.

Plants in tidal habitats must also cope with sea level rise. As of 2018, around the Chesapeake Bay, sea level is rising at a rate of ¾”to 1” every 5 years. Additionally, tidal environments are being pounded by more intense storms. Unfortunately, upslope migration is often blocked by hardened shorelines.

There are several things you can do to make your native garden plants more resilient to climate change. For example, don’t plant natives in conditions that are too sunny or too dry for them, and avoid species that are near the southern end of their natural range. Gardeners can also help protect wild native plants by helping to preserve natural area corridors that species need for migration. You can get more detail on these topics by visiting our Native Plants and Climate Change webpage.

Trees are different from other types of native plants because they live longer.
Trees are different from other types of native plants because they live longer. If you buy a tree now, you need to select one that will be adapted to temperatures in the year 2100. In a best-case scenario (society begins to curb climate emissions now, left), the arrows point to where Marylanders should currently source native trees from.  In a worst-case scenario (we do not change our emissions behavior), the red arrows (right) indicate where you should source native trees. These maps also show about how quickly plants would need to migrate. Could they migrate from Virginia to Maryland by the end of the century? Seems possible. From Georgia to Maryland? Less likely.

By Sara Tangren, Ph. D., Senior Agent Associate, Sustainable Horticulture and Native Plants, University of Maryland Extension, Home & Garden Information Center (HGIC)

My Pachysandra is Dying, What Can I Plant in Its Place?

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landscape in partial shadeResident seeks groundcover options to replace Pachysandra. Photo: University of Maryland Extension / Ask an Expert

Q: My Pachysandra is Dying, What Can I Plant in Its Place?

A patch of Japanese Pachysandra in my yard was formerly healthy but in the past three years, it has died back. I would like to plant deer-resistant plants or groundcover in its place. Can you recommend some perennials I can try? This area gets filtered sun most of the day.

Answer: Volutella is a common fungal disease of Japanese Pachysandra that attacks both the leaves and stems and causes dieback symptoms. It is most severe in overgrown plantings and is often associated with scale (insect) infestations. This may have contributed to the decline of your plants.

It is a good idea to consider different options for this space. In addition to its susceptibility to Volutella dieback, Japanese Pachysandra has escaped garden cultivation and is now invasive in some natural areas of Maryland. We no longer recommend planting it. In the forest understory, it outcompetes native plants such as our spring ephemeral wildflowers and the wildlife (insects, birds) they support.

japanese pachysandra in a forested area
Invasive Pachysandra terminalis covers a large area of forested ground in Howard, County, Maryland. Photo: C. Carignan

There are other groundcover choices that are unique, beautiful, non-invasive, and adapted to Maryland’s growing conditions. For a partially shaded, moist area, try a combination of ferns – Christmas fern (Polystichum acrostichoides) and marginal woodfern (Dryopteris marginalis), sedges – blue wood sedges (Carex glaucodea or Carex laxiculmus) and Pennsylvania sedge (Carex pensylvanica), Canadian ginger (Asarum canadense), golden groundsel (Packera aurea), foam flower (Tiarella cordifolia), and creeping phlox (Phlox stolonifera). Some of these plants also support pollinators.

native plants garden
Groundcover plants were in bloom in April in the native plants garden at Camden Yards, Baltimore. From front to back: Phlox, Foamflower, Golden Groundsel. Photo: C. Carignan

Additional Resources

Planting Groundcovers | Home & Garden Information Center

Twelve Easy Native Plants for Shade | Montgomery County Department of Environmental Protection

Groundcovers | Plant NOVA Natives

By Christa K. Carignan, Maryland Certified Professional Horticulturist, Coordinator, University of Maryland Extension Home & Garden Information Center

Have a plant or insect question? University of Maryland Extension’s experts have answers! Send your questions and photos to Ask an Expert.

Karifurore or Fioretto cauliflower

Maryland Grows2 Comments

You know how sometimes you just – quick! snap a photo, and then it takes you down a rabbit hole? I was recently in a market in Fuling, China (that was the big trip I posted about preparing for last month), eagerly photographing the displays of produce, and got this shot:

IMG_5432

We’d been served this vegetable at meals several times previously. It’s clearly cauliflower, but not a variety I was familiar with – all loose and lacy, with lots of delicate stem.

So I got back, and recovered from jet lag, and was casting around for a topic for today’s post, and remembered the cauliflower. What the heck was that? It took a little google-fu to get started – “Asian cauliflower” just provides recipes, but “Asian cauliflower varieties” began to yield results. Continue reading →

Dandelion Greens: Glad I’m Not a Starving Colonist

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My son stood in the back of the pick up truck surveying his work. His eyes were wide, arms outstretched, and his jaw slack in amazement. “Did I plant all of this?” he asked, as he pointed to the broad swaths of brilliant yellow dandelions smothering the field, encroaching on the lawn. Grady did help sow those dandelions, but he was not alone. Many kids have blown dandelion seeds in my yard with great delight, hoping that their wishes would come true.

girl blowing dandelion seeds
Katy Hill makes a wish as she ensures the proliferation of dandelions. Photo: Susie Hill

If I were to turn back the hands of time to the era of our early American ancestors, I would be monumentally proud of my kids. Ours is an old farmhouse that was a one-room cabin in the 1700’s. If I lived in this house back then, I would have spent my winter subsisting on pork rinds, corn bread, and half rotten squashes from the root cellar. I would have jumped for joy at the sight of emerging dandelion greens. After all, colonists brought dandelions to the new world. They were a welcome addition to the dinner plate after long, vitamin deficient winters.

I am so glad that I am not a starving colonist. Green is my favorite color to eat. I grow a lot of my own greens, but when those are unavailable, I do not suffer through a long winter, waiting on bated breath for poke greens and dandelions. I just go to the store and buy what I want. I have tried, but to date, I have not developed a taste for dandelion greens. I have tried them in salad- never again. I have tried dandelion wine- not my favorite. I tried feeding them to my chickens- they turned up their beaks.

dandelion leaves
Dandelion greens. Photo: Pixabay

Hoping to find a way to reduce my dandelion colony, I thought I would try feeding them to my eldest sister. She is an extraordinary cook and she has a broad culinary palate. In the early 90’s she paid $6.00 for a bunch of purslane, a weed that grows prolifically in my sidewalk. She seemed the most likely taste tester. When I visit my sister in Manhattan, I always bring produce, eggs, and flowers. On one visit, I brought dandelion greens. I spent an hour carefully selecting the best rosettes I could find. I triple washed them and brought them bagged and ready to eat. She did eat them because of the effort involved in getting them to her, but they were so bitter that she said she had to choke them down.

On my way home from the city, I stopped in a Pennsylvania Dutch meat market where they just happened to have bags of dandelion greens for sale. I inquired about how to prepare them and the woman behind the counter told me that you must dig them when the rosettes are very small. Clean them well. Then cook them with lard and bacon, topped with hard-boiled eggs. It seems the only part of this process I got right was the triple washing.

dandelions
Dandelion flowers. Photo: Pixabay

This spring, I shall try them again. I’ll probably skip the extra lard but will surely cook them with bacon. I will dig the rosettes when they are very small and I will triple wash them with care. If after that, I do not like them, I will not eat them again until I am starving to death following the next apocalypse. Surely, dandelions will survive an apocalypse. Maybe then, I will actually turn to Grady and all the other kids in my life and thank them for a job well done.

Susie Hill is a University of Maryland Extension Master Gardener in Frederick County and a former HGIC Horticulture Consultant.

Filling Your Raised Bed

Maryland Grows6 Comments

Healthy soil will help you produce healthy crops. Ideal vegetable garden soil should be loose, deep, and crumbly. It both holds water for root uptake and allows excess rainfall to quickly percolate downward. So how do you fill a raised bed? Should you add topsoil, compost, or potting soil? The answer depends on the situation. Read the scenarios below to learn about options and develop an approach that works best for you!

Scenario 1:

Reduce costs by foregoing an enclosure. Photo credit: Jon Traunfeld
Reduce costs by foregoing an enclosure.
Photo credit: Jon Traunfeld

Raised beds without a wood enclosure- formed by “pulling up” loose, fertile topsoil into a 2-6 inch raised bed with gently sloped sides. Spread 1-2 inches of compost on the area before forming the beds. Continue reading →

Q&A: How Can I Make a Naturalistic Garden Look Intentional?

Maryland Grows3 Comments
blue sedge
Blue sedge. Photo: Ellen Nibali

Q: I would like to plant a more natural garden but am worried about irritating the neighbors who might think it is sloppy or not a garden at all! Any advice?

A: Make a natural garden look intentional. Here are three major design tips to make a garden’s intent obvious:

1) Give it obvious edges. Edges can be botanical, such as a row of blue sedges (pictured) or can be hardscapes such as pavers, bricks, a path, low wall, or low fencing.

2) Give it an obvious shape. This can be geometrical lines and angles (circle, triangle, parallelogram, etc.) but also can be flowing lines made obvious with big or repeated curves.

3) Within the beds, make plant choices obvious. Use blocks or ribbons of plants, repetition of key species, or a predominant plant family (e.g. grasses) with a few other species mixed in. Of course, banish all invasive plants. Use at least 70 percent native plants.

By Ellen Nibali, Horticulturist (retired), University of Maryland Extension Home and Garden Information Center. 

Do you have a gardening question? University of Maryland Extension experts have answers! Send your questions and photos to Ask Extension.