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.

Comfy plant places and new garden spaces for vegetables

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

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.

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

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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Fighting CO2 on a Balcony

It’s well known that atmospheric carbon dioxide (CO2) is one of the leading causes of climate change and that plants play a role in mitigating its impact by taking in carbon dioxide and releasing oxygen. But did you know that even the smallest gardens can make a difference? Container gardens can be effective ways for adding plants to the ecosystem, nurturing pollinators and other beneficial insects, and even providing food for your table.

A container garden with mixed perennials and annuals provides beauty, food, and habitat. Photo: Pat Wilson

High above Columbia’s Wilde Lake at the Residences at Vantage Point, long-time gardener Barbara Schuyler continues the gardening that was her passion when she and her wife Pat Wilson lived on a rural property. More than 90 containers of shrubs, annuals, perennials, and vegetables grace two balconies that face west and south.

Barbara’s approach to container gardening

Shrubs and perennials comprise a significant part of the garden. Hardy perennials winter over and are especially effective at drawing down carbon dioxide. Some of the perennials, like the orange butterfly milkweed (Asclepias tuberosa) pictured below, are natives. Native plants are well-suited to our climate, require less care than imported species, and support native insects. Barbara’s native plants also include lots of Rudbeckia, some Echinacea, and several Heuchera

orange and blue flowers planted in a container garden
Native butterfly milkweed (orange flowers) combines beautifully with the blue-theme flowers. Photo: Barbara Schuyler

In addition, each year Barbara and Pat decide on a theme and collect annual seeds to plant when the temperature warms up each spring. Last year, the blue flower theme provided a consistent backdrop for the foliage and flowers of other plants.

She uses regular potting soil and each spring spreads the old soil on a tarp to remove roots and debris and returns it to the pots with a portion of fresh potting soil added.

Her collection of containers is eclectic and includes salad tables for vegetables, wine barrels, ceramic and plastic pots. A container exchange in the building helps many patio gardeners find pots that meet specific size and decorative needs. Reusing and sharing materials can help reduce CO2 associated with buying and shipping new products. She also tried felt bags but was not pleased with the results.

spray handle attached to kitchen sink
Photo: Christine Hipple

Watering 90 containers with a watering can during dry spells would be a major challenge, so Barbara purchased a garden hose sink adapter to allow her to connect a lightweight flexible hose to the kitchen sink.  

One big advantage of balcony gardens is that deer can’t get to them, though she has seen a squirrel or two.

Benefits

Visiting her garden every morning is a joy in itself. It provides Barbara the opportunity to be present with her plants, be aware of their needs, and appreciate what they offer throughout the seasons.

Even at this extreme height, pollinators are attracted to and supported by the garden. Three species of bees, several types of moths, and even a few monarchs have been spotted.

Lettuce and arugula do well in pots, and along with cherry tomatoes provide healthy super-local produce — yet another reduction in their carbon footprint. One lesson Barbara’s learned about cherry tomatoes is not to crowd them. Plant just one to a large pot and prune assertively to be sure the energy goes into making tomatoes rather than excess foliage and that there’s sufficient air circulation.

cherry tomatoes ripening
Growing some food at home is fun and helps reduce the carbon footprint of food transport. Photo: Barbara Schuyler

While there’s some level of physical work involved, container gardening is within the reach of nearly everyone – no matter your available space, skill level, physical abilities, or budget. Start small. Share stories, plants, and pots with other gardeners, and enjoy the benefits for yourself, your community, and the planet!

Are you taking any steps in your garden to help mitigate and adapt to climate change? Have a story to share? Let us know! Leave a comment or contact us.

By Christine Hipple, University of Maryland Extension Master Gardener, Howard County, Maryland

Starting a compost pile and planting cover crops – winding down the vegetable garden for the year

After a fun year of building support structures and growing really long squash, it was time to wind down the garden. Our first baby was born (thank you, thank you), and we had no further bandwidth or ambition to continue with cool-season crops, so I decided to pack up the support gear, rip out the remaining plants that were producing but slowing down, start a compost pile with the remains, and plant cover crops in the beds.

Packing it up

My big trellis used for the Tromboncino squash and the one made from part of a fencing panel used for tomatoes both folded up and packed away nicely in this outdoor storage area attached to my house. I’m happy with my designs, as I didn’t want permanent structures out in the garden getting weathered, and I didn’t want them to take up a lot of space in storage. These will be easy to set up next year again. The only thing I will do differently in the future is to use something stronger than twine to string on the trellis and hold up tomatoes with tomato clips. A lot of the twine that was under pressure from crops eventually snapped and needed replacing.

Rip it, chop it, bin it

We were going to have such a volume of garden waste this year, I decided to start a compost bin. This should give us a head start on the new layer of compost (previously all store-bought) we add to the raised beds each year. Pretty much all we have to do is throw this stuff in a bin and wait, as we are doing passive composting that is slow but requires very little attention.

I bought a cheap compost bin online; this one is just a sheet of black plastic with holes that you form into a vertical cylinder and throw your stuff into.

I ripped up our squash, watermelon, and tomato plants, wheelbarrowed ’em over to the compost bin in our back yard, stabbed at the pile with a shovel and buzzed it with my string trimmer for a while to chop it up a bit. Then I shoveled it all into the bin, attempting to mix up the types of plants in there somewhat uniformly.

Once leaves fall, I’ll drop some leaves that have been shredded by the mower into there as well.

I know you can drop food waste like fruit and vegetable scraps into compost, but I’m not sure we are going bother making the trip from the kitchen to backyard with a couple banana peels since that’s just not a lot of volume to make a difference for our intended purpose.

We will need to turn the pile a couple times in the next year to aid decomposition, but other than that, this is hands off. I’m looking forward to seeing what we get at the beginning of next growing season to start our summer vegetable garden again.

Cover crops for our raised bed garden to make it through the winter

I know it is good to protect my soil from erosion and add a layer of compostable material on the top over the winter. Last year, I had read that a layer of mulched leaves is good to place into raised beds, but when I did that, I found that much of it quickly blew away.

This year, I decided to plant crimson clover, a cover crop.

Cover crops, also known as green manures, are an excellent tool for vegetable gardeners, especially where manures and compost are unavailable. They lessen soil erosion during the winter, add organic material when turned under in the spring, improve soil quality, and add valuable nutrients.

HGIC page on cover crops

With a couple inexpensive packets of crimson clover, I sprinkled the seeds over the now empty raised beds, raked a bit to cover them lightly with soil, and then watered the soil most days. I could see sprouts in a week or so.

The clover will add a layer of protection over the winter, and then nitrogen and nutrients in April when I cut it down with a string trimmer and then turn over the soil.

Sounds easy enough. I’m all about lower-effort gardening!

Dan Adler
HGIC Web Support and Video Production

Plants not behaving as expected: vegetable garden edition

Two of the vegetable crops I grew this year are known for loving the heat: okra and eggplant. I grow eggplant in pots on my deck, to avoid flea beetle infestation, and okra directly in the ground in my community garden plot. Both of them produced adequately over the summer. Now it’s fall; we’re having days in the 70s and nights in the 50s, and there are fewer hours of sunlight in the day. Time to pull the summer crops, right?

Except – boom! Both the okra and the eggplant are going gangbusters. More flowers, more fruits than in the hot summer months, by far.

‘Bride’ eggplant on a cool autumn morning

So why aren’t these plants following the rulebook? Do they not know how to read? Or have the rules changed?

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