Spring Ephemerals – The Garden Thyme Podcast

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April is National Garden Month! So Happy National Garden Month everyone. One of the clearest signals of spring is the emergence of spring ephemerals — daffodils, crocus, tulips… these bulbs are some classic examples — but we have so many more to enjoy! Our woodland wildflowers may be more subtle, but are no less impressive and are even more rewarding. This month we take a break from our garden and all the spring chores to talk about some of our favorite woodland spring ephemerals.

Ephemerals covered in this episode include Dutchman’s breeches, Virginia bluebells, mayapples, bellworts, spring beauty, Jack-in-the-pulpit, and pink lady slipper. 

We also have our: 

  • Native Plant of the Month (Sessile trillium) at 22:15
  • Bug of the Month (Termites) at 25:35
  • Garden Tips of the Month at (36:55)

If you have any garden-related questions please email us at UMEGardenPodcast@gmail.com or look us up on Facebook.

The Garden Thyme Podcast is brought to you by the University of Maryland Extension. Hosts are Mikaela Boley, Senior Agent Associate (Talbot County) for Horticulture; Rachel Rhodes, Agent Associate for Horticulture (Queen Anne’s County); and Emily Zobel, Senior Agent Associate for Agriculture (Dorchester County).

Theme Song: By Jason Inc

Improve Soil Health for a Climate-Resilient Garden

Soils, plants, and animals are highly interdependent. Soils support and feed microbes and plants which feed animals. Dead plants and soil critters replenish the soils’ organic matter and nutrient supply, completing the cycle. We know that healthy soils produce healthy plants. Many experts believe that improving soil health is the most important thing we can do to make our farms and gardens more climate-resilient. 

Why are soils so important in dealing with climate change? 

  • They store huge amounts of carbon in the form of carbon dioxide (CO2) and organic matter, all of the living, dead, and decomposing plants, microbes, and animals that live in soil. Carbon dioxide is the primary greenhouse gas that is warming the planet. Deforestation, the removal of wetlands and peatlands, and soil tillage cause the release of huge amounts of CO2. Warmer temperatures cause more rapid organic matter decomposition and turnover, especially if soils are tilled and uncovered.
  • Climate change is causing mid-Atlantic weather to be warmer and wetter with more extreme weather events, including periodic drought. This increases the risk of soil erosion and nutrient run-off from intense rainfall, and the risk of plant stress from excessively wet or dry soils. 
Soil from a landscaping project that moved off-site in 2018. Maryland averaged 73 inches of rain that year!
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Q&A: Why do my hollies and other evergreens have brown and pale leaves?

holly with leaves showing sections of brown and pale color
Winterburn symptoms on holly. Photo: David L. Clement, University of Maryland Extension

Q: Several of our evergreens (different kinds) have brown or pale, bleached-looking leaves. Do they have a disease already, and can anything be done? Is it preventable in the future?

A: Most likely it’s winterburn, especially since most infectious diseases won’t cause symptoms this early and seldom impact several unrelated plants to the same degree. Winterburn is an abiotic disorder or injury – abiotic translates to without (a-) life (biotic) – meaning the condition has a non-living cause. Abiotic plant disorders are environmental, and causes include wind, water, temperature, and soil pH. In comparison, biotic factors would include insects, mites, fungi, or bacteria.

No treatment is recommended because the damage has been done, but winterburn is rarely a serious threat to a plant’s long-term health. As new growth resumes, the plant will eventually shed the damaged leaves. If it’s too much of an eyesore, you can selectively trim away the worst of it this month. Causes for winterburn typically involve a combination of cold temperatures, wind, and exposure to sun. Any autumn pruning that results in tender regrowth is priming a plant for winterburn, which is one reason it’s not recommended.

Why are cold-hardy evergreens damaged? Leaves “breathe” through tiny pores on their surface, and this gas exchange also allows water vapor to leave the leaf. Moisture leaves our bodies the same way – picture foggy breath on a cold day. Breezy days, especially in winter’s drier air, speeds-up this evaporation, as can the sun’s weak warmth. Meanwhile, during cold snaps, moisture in the surface layers of soil freezes, which prevents roots from absorbing it. Since the plant cannot replenish all of the moisture it’s losing, the leaf tissue starts to essentially freeze-dry. A thaw won’t reverse the damage because the cells have been injured, just like skin with frostbite. (Unlike our skin though, which can heal to an extent, leaf tissue can’t repair itself.)

Broadleaf evergreens are more vulnerable to winterburn than needled evergreens because the leaf surface area and evaporation potential is so much greater. Younger plants also have greater vulnerability because they are still establishing roots. This is the main reason it’s risky to plant evergreens late in the fall. Cherry laurel, boxwood, holly, rhododendron, camellia, and southern and sweetbay magnolias are common winterburn victims in our area. Plants kept in containers are also susceptible because their roots dry faster and experience more drastic temperature swings than they would in the ground.

The only actions you can take to minimize winterburn risk is to site evergreens out of the brunt of winter winds and to periodically monitor their root zones for moisture, irrigating when dry during a warm spell. Plants overwintering in pots can be sheltered a bit near a wall or windbreak, but don’t bring them inside as the interruption of dormancy may detriment their health.

Learn more and see additional photos on the Home & Garden Information Center website: Winter Damage on Landscape Plants.

By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun. 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.

What are local ecotype plants and why do they matter to pollinators?

With the planting season upon us, many of us are starting to think about what flowers may be the best for our gardens and pollinators. We may have started to look into floral mixes or even flower starts, but probably there are too many choices and now we’re overwhelmed and don’t know what to do. In previous posts, we talked about the importance of diverse floral choices and how appropriate native species are when choosing plants for pollinators. There is, however, an extra twist that is becoming more mainstream in this story and today I want to talk about it. Let’s chat about local ecotypes, what they are, what they contribute, and how to get them (and how to not get them).

What are local ecotypes?

In a few words, local ecotypes are native plant species that have a genetic background typical for the local region and adapted to it. I know, there were a lot of technical words in that sentence, so let me break it down to make it easier to understand.

Like all organisms, plants have lineages that reflect their ancestry. In the same way that we as humans are genetically more closely related to members of our own family than to those of other families, plant populations are also more closely related to other plants of the same species that live close to them. From a genetic point of view, this means that plants that come from regions close to each other will tend to have more similar genetic characteristics than those from regions far apart from each other. This genetic makeup specific to a given region is what we call broadly a local genotype.

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DC’s Famous Cherry Trees: Keeping Them Healthy in the Face of Pests, Floods, and More

a collage of cherry trees showing pink and white flowers
A collage of cherry (Prunus spp.) blossoms, some of which can be found in Washington DC. The species and varieties vary in blossom color, size, and shape. Credit: LiveJapan

Just across Maryland’s border, millions of people flock to Washington, DC at this time of year to witness the spectacular display of 3,000+ cherry trees in bloom around the Tidal Basin. Keeping these famous trees healthy from pests, predicting the timing of peak bloom, and mitigating the threat of rising tides from climate change are among the challenges that need to be addressed to keep these cherished plants in top form for people to enjoy now and for many years to come.

Dr. Lauren Schmitt, an ecologist working with the Burghardt lab in the University of Maryland’s Entomology Department, gives us a close look at the history of these magnificent trees, how pests are managed using an Integrated Pest Management (IPM) approach, how peak bloom times are predicted, and how some of the non-pest threats such as soil compaction and flooding are being addressed.

Read her two part-series on DC’s Famous Cherry Trees:

Part 1: A Case Study For IPM 

Part 2: Variation In The Trees And Varied Threats To Their Health 

Lauren Schmitt, Ph.D. is an ecologist working at the intersection of ecosystem ecology and community ecology. A member of the University of Maryland Burghardt Lab, her research focuses on linking biodiversity and ecosystem function. Much of her work takes place in a forest diversity experiment, “BiodiversiTREE” to assess how tree diversity shapes communities and ecosystem processes.

Soil temperature and why it matters

soil thermometer in the ground
Soil thermometer. Photo: A. Bodkins

Sunshine, increasing temperatures, warm rain showers, and the return of migratory birds are all signs that Spring is getting closer. They are all reasons to be excited about Spring and all the possibilities that the new gardening season will hold.  

It’s always tempting to go out and start sowing seeds at the first glimpse of sunshine, but most seasoned gardeners know that patience is the best policy. It takes several weeks of warm air temperatures and sunshine for the soil temperature to get warm enough to signal the seeds to germinate. Mother nature provides mechanisms to protect seeds from germinating too early (called “seed dormancy”) and there are certain requirements that must be met before sprouting occurs. 

Did you know that every seed has an optimum range of soil temperatures for germination? This factor helps determine which seeds are cool-season versus warm-season. Penn State Extension has a great article regarding Soil Temperature and Seed Germination that you should spend a few minutes reading. 

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Helping pollinators in small green spaces

Spring is almost almost aaaaaalmost here, and if you’re like me, you have already started visualizing what flowers will grow where and what pollinators you’ll need to keep an eye out for. Unlike in other posts, where we talked about how to help pollinators in large spaces, today we’ll talk about how to help them in very small yards, balconies, porches, or other small spaces.

small garden in front of a town home
Having a small yard is no reason to not help pollinators. Small yards can be great spaces to support them! Photo: G. Cripezzi.

Small yards

If you have access to a small yard, plenty of opportunities are available! Of course, you will not be able to plant lots of large plants, but that doesn’t mean you cannot plant anything. When offered little space, you can use not just the horizontal, but also the vertical space. While it is possible to cover the ground with a mix of perennials and annuals, there are also possibilities of installing trellises on which flowering vines can grow.

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