Climate Change

Climate Change and Sea Level Rise with Dr. Kate McClure – The Garden Thyme Podcast

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Nuisance flooding. Photo by Howard F. Schwartz, Colorado State University, Bugwood.org.
Staghorn sumac flower. Photo by Ohio State Weed Lab , The Ohio State University, Bugwood.org

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In this month’s episode, we are speaking all about Climate Change and Sea Level Rise with Dr. Kate McClure from the University of Maryland Sea Grant Extension Program. We talk about the effects of climate change that we are seeing right now and what sea level rise looks like.

Dr. McClure also gives us some online prediction tools to help us better plan our landscape for the future. 

We also have our: 

  •  Native Plant of the Month – Staghorn sumac (Rhus typhina)
  • Bug of the Month – Baltimore checkerspot (Euphydryas phaeton)
  • Garden Tips of the Month

If you have any garden-related questions, please email us at UMEGardenPodcast@gmail.com or look us up on Facebook at https://www.facebook.com/GardenThymePodcas. For more information about UME and these topics, please check out the UME Home and Garden Information Center and Maryland Grows Blog at https://marylandgrows.umd.edu/. 

 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

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Pollination of Vegetable Crops in a Warming Climate

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Pollination is the movement of pollen from male to female flower parts of sexually reproducing plants. It is often accomplished by wind and insects and results in the development of some type of fruit containing seeds for the species’ continuation. Farmers and gardeners in the mid-Atlantic are finding that high day and evening temperatures can cause vegetable plants to drop flowers and small fruits or produce deformed and under-sized fruits. This  problem has been observed in crops like bean, tomato, and pepper (mostly self-fertile; individual flowers can pollinate themselves), and in crops like squash and pumpkin (require cross-pollination between flowers).

How do high temperatures affect pollination?

All fruiting plants have an optimal temperature range for the pollination/fertilization process. High temperatures can reduce pollen production, prevent anthers from releasing pollen, kill pollen outright, and interfere with the pollen tubes that serve as conduits for uniting sperm cells and eggs (fertilization) inside undeveloped seeds (ovules). High temperatures can even injure flowers before they open. Night temperatures are increasing at a faster rate than day temperatures as a result of climate change, and seem to be most responsible for these pollination problems.

pollination of a flower
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Improve Soil Health for a Climate-Resilient Garden

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

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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.

Comfy plant places and new garden spaces for vegetables

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Every time we plant a seed or baby plant in our vegetable garden we are hoping for the best outcome- a healthy crop and big harvest. Gardening success comes from learning about the needs of our crops and doing all we can to meet those needs. Climate change is causing us to think a little more deeply and holistically about those plant needs and our gardening practices.

In addition to making sure that plants have enough space, water, and healthy soil, we can alter how and where we plant our crops (“comfy places”) to help them adapt to increasing summer temperatures. We can also consider ways to expand or shift our food garden spots (“new spaces”) to better manage growing conditions and produce more food.

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Peat-free potting mixes

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Sphagnum peat moss is valuable in horticulture because its fibrous structure helps it retain a lot of water and air while draining excess water. This has made peat a primary ingredient of soilless growing media (potting mix) around the world. These stable, light-weight, and porous products have been filling the benches, flats, and containers of greenhouse and nursery operators and flower and vegetable growers for decades. You’d be hard-pressed to find a gardener who has not benefited from soilless potting mixes for starting and growing plants, inside and outside.

lettuce seedling showing roots and potting medium
vegetable seedlings
Peat-based growing mixes allow rapid germination and root
growth, and healthy transplants.

What’s the problem with peat?

Peat is an organic substance formed from mosses, reeds, and sedges that accumulates and decomposes very slowly in waterlogged soils (bogs). Peatlands hold 30% of the earth’s soil carbon and occur mostly in cold, temperate regions. “Peat moss” used in horticulture typically refers to mosses in the Sphagnum genus.

The problem with peat is three-fold: stripping off peat from peatlands disturbs complex ecosystems; excavation releases enormous amounts of CO2, a major greenhouse gas driving climate change; and demand for peat-based soilless media is growing.

For decades, there have been calls to conserve the U.K.’s dwindling peatlands. Timelines are in place for soon phasing out peat as a growing media for gardeners and commercial growers. Most sphagnum peat is from Canada and there are no indications that Canada, with its vast peat reserves, will follow suit. But public demand for peat-free alternatives will drive the industry to develop new products.

Reducing the use of peat in horticulture will mitigate climate change and increase reliance on local materials as peat substitutes.

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Heat-tolerant vegetable crops and cultivars for the changing climate

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Our food-growing spaces allow us to grow healthy produce, connect with Nature, and hopefully save money. They are also a solid response to climate change and COVID.

My blog articles this year will be about climate-resilient food gardening. Each month I’ll address one or more aspects of how climate change is affecting our food gardens and changes we can make to reduce global warming and ensure a future of healthy harvests.

HGIC has a new Climate-Resilient Gardening section (thanks to Christa Carignan!) where you’ll find more information on these topics. We plan to continually update content and add new pages. And please check out the University of Maryland Extension’s new Healthy Garden, Healthy You project that connects food gardening and human health.

This first installment includes an overview of how our mid-Atlantic climate is changing and a look at heat-tolerant crops and cultivars. Future articles will explore low-dig soil prep, composting food scraps, peat alternatives, heat stress in plants, reducing plastics, and “hardening” our garden spaces.

Resiliency is mentioned a lot with respect to climate change. A climate-resilient garden can both withstand and recover from warmer, more extreme weather. Resiliency can also mean transforming how we grow food by creating and sharing a community knowledgebase of new ideas and techniques.

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