Knowing when it’s time: Season’s end

The last Brandywine

I took out my tomato plants this week. It’s a lot earlier than I’d normally do it, but I had my reasons (which I will discuss below). Picking the last fruits and chopping down the stems made me think about all the decisions we make as gardeners, and how a lot of the questions we Master Gardeners get are about those choices. We might get asked at this time of year, “Am I supposed to take out my tomato plants now?” Maybe with an undercurrent of “Will I get in trouble with the garden police if I do it? Or don’t do it?” but in any case with uncertainty about doing the right thing. And the disappointing answer we long-experienced garden gurus usually give to questions like that?

“Well, it depends.”

Or, even more frustratingly: “It’s up to you.”

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Q&A: Why are lilac leaves brown and curling?

Irregular brown spots and blotches appear on lilac leaves, followed by leaf curling and defoliation in late summer. Photo: UME Ask Extension

Q: My lilacs look like death-warmed-over this time of year. Do you know what’s wrong, and is there anything I can do at this point?

A: Lilacs are sadly not very well-suited to our mid-Atlantic conditions. We’re at the southern edge of their heat tolerance, so while they weren’t among the best flowering shrub choices to begin with, climate change is only going to worsen their prognosis. Several types of leaf-spotting fungi and bacteria, plus general heat stress (which also increases their vulnerability to borers), results in foliage that looks quite beat-up by late summer. Brown spots, crispy leaf edges, and bare stems from premature leaf drop are all typical. You can explore lilac ailments and their management on our lilac diagnostic page.

No fungicide will reverse these symptoms once they appear, and while they might work as a preventative if applied before bud-break (and re-applied repeatedly well into the summer), it’s simpler to just grow something else if a plant is going to be that much of a hassle. This is especially true if the treatments don’t work and the plant still winds up looking horrible. Fungicides also carry the risk of harming other organisms.

For now, you can rake up and dispose of any fallen leaves, though this isn’t a foolproof way of removing a source of infectious spores. Cut down the oldest, thickest stems this winter (they tend not to bloom well at that age anyway) and open up the canopy by selectively removing some stems that contribute to foliage crowding. You can do this thinning after bloom next spring.

For anyone really wanting to grow lilac despite these challenges, try cultivars with above-average disease resistance and heat tolerance. While not immune to problems, they perform much better, even if they don’t look exactly the same or have blooms as large or heavily perfumed. ‘Miss Kim’ is a round, compact-growing cultivar with pale lavender-purple flowers that’s been around for decades. Other varieties are now available with pink or deeper purple blooms, some of which even rebloom a bit, sporadically producing flowers into summer and early autumn, though high heat could still hamper that.

dwarf lilac with lavender flowers
Dwarf lilac species and hybrids handle Maryland conditions much better than the traditional varieties. Some recent introductions will also re-bloom sporadically later in the summer. Photo: M. Talabac

All lilacs, but especially the traditional, classic “French” types, should be planted in a location with great air circulation (so, not up against a fence or wall) so wet leaves dry quickly after rain, dew, or irrigation. Wet foliage is more easily infected by pathogens.

The main perk of growing lilacs is fragrance, so if you want a scented replacement, consider: Winterhazel (Corylopsis), Koreanspice Viburnum (Viburnum carlesii) and its hybrids, Summersweet (Clethra), Seven-son Flower (Heptacodium), Carolina Allspice (Calycanthus), various deciduous Azaleas (Rhododendron viscosum and several others), Mockorange (Philadelphus), and Fragrant Abelia (Abelia mosanensis). Their scent characteristics, flower colors, mature sizes, and preferred growing conditions may differ from lilac, but nothing is going to be an exact substitute. Plus, several of these species will offer the additional bonus of showy autumn foliage or (for the native ones) better wildlife value. These are just some shrub ideas; there are also fragrant perennials and, if you have the room, several fragrant trees.

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

Have a plant or insect question? University of Maryland Extension has answers! Send your questions and photos to Ask Extension.

How to adapt your garden to climate change

The news is filled with references to global warming and climate change. In fact, 99% of scientists agree that climate change is real with negative impacts on the environment, weather, human health, and agriculture. In Maryland, climate change is already causing higher average temperatures, more drought, longer heat waves, more intense storms, and flooding. 

So what can we do as gardeners to help the cause and help our gardens adapt to these changes?

Adopt sustainable practices. Environmentally smart practices build climate-resilient gardens and can slow future warming by reducing emissions and boosting carbon in soil and plants. Here are a few ways to get started:

Plant more trees

Trees filter air and water and are carbon sinks, capturing and storing carbon dioxide, a key greenhouse gas. When placed well, trees can save up to 30 percent on heating and cooling costs.  

  • Plant deciduous trees on the west, east or southwest side of your home to block summer sun then let it in to warm your home in winter. Site evergreens to the northwest to buffer winter winds. 
  • Lean toward native trees. They’re well-adapted and need less water and fertilizer, the manufacture of which can contribute to greenhouse gases.  

Add or nurture native plants

Don’t stop with trees. Native shrubs, perennials, grasses, and groundcovers also help build a climate-resilient landscape. Native plants, once established, require less water and fertilizer, help store carbon, and reduce soil erosion. Since they co-evolved, native plants best support native pollinators and beneficial insects which provide chemical-free pest control. 

HGIC Website: Native Plants and Climate Change

Keep it diverse

Plant diversity also boosts resistance to pests and disease, so add many different types of plants to your gardens. Yes, more is better. 

Save the soil

Washington County Master Gardener Gary Stallings turns compost, a tool in building soil health and climate resilience

Great gardens grow from the ground up. So protect and improve your soil which stores massive amounts of carbon as carbon dioxide and organic matter.  

  • Keep soil covered since bare soil invites problems. Soil covered with plants, mulch, or cover crops best stores carbon, resists erosion, holds moisture, and has more even temperatures. 
  • Minimize soil disturbance from digging and tilling which speeds up the loss of organic matter and disturbs the soil community.  
  • Recycle nutrients by making and using compost. Compost adds organic matter, helps soil hold water and nutrients, and reduces the need for fertilizers. 

HGIC Website: Improve Soil Health for a Climate-Resilient Garden

Water wisely

  • Save water to make your garden more climate-resilient. Use a rain barrel or create a rain garden to capture and filter rainwater.  
  • Water when plants need it, not on a fixed schedule. And plant in the spring or fall when plants need less water to become established.

A few more tips:

  • Limit the emissions that contribute to greenhouse gases. Use gas-powered mowers, trimmers, and other equipment less and opt for alternatives. 
  • Shrink your lawn and replace it with groundcovers and other alternatives which need less water, mowing, herbicides, and fertilizer. When you do fertilize, do it based on a soil test to use only what you need. 
  • Help more by growing some of your own food or supporting local growers to cut down on emissions from long-distance transportation. 

You can make your garden more climate-resilient. Start with a few steps and build on them to help your garden successfully adapt to climate change.   

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.

This article was previously published by Herald-Mail Media.

What is so special about legumes? 

a collage of three photos shows alfalfa plants growing in a high tunnel
Alfalfa (a legume) with nasturtium growing at the edge of a high tunnel. Photo: A. Bodkins

There is a whole group of plants in the Leguminosae (a.k.a Fabaceae) plant family and are referred to as legumes, a word that many people may have heard but may not know the special details about. Have you ever heard that legumes make their own nitrogen or that they are plants that never need nitrogen fertilizer? Well, both those statements are true! 

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Maryland gardeners are adapting to climate change

How are Maryland gardeners adapting their gardens and green spaces to climate change? We posed this question to our colleagues in the University of Maryland College of Agriculture and Natural Resources and several of them shared examples of everything from composting and food gardening to planting trees and native plants, installing rain gardens, and more.

Action on climate change is needed on a large scale, and our individual actions at home and in our communities all add up too. Check out our Story Map showcasing the variety of ways Marylanders are adapting their green spaces with climate change and sustainability in mind. Then take our quick poll at the end of the Story Map and let us know: Are you doing climate-resilient gardening?

Screen shot of the climate-resilient gardening story map

View the Story Map

Learn more:

By Christa K. Carignan, Coordinator, Digital Horticulture Education, University of Maryland Extension Home & Garden Information Center. Read more posts by Christa.

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

Listen to the podcast

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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Poison ivy management strategy: scorched earth or pick my battles?

Recently, as I was walking my property and spotting some more returning poison ivy here and there and lamenting the existence and stubbornness of this pesky weed, a novel thought (for me) popped into my head: I know poison ivy is a native plant – does this mean it is right to totally eradicate it?

A study showing more CO2 in the atmosphere means we might get stronger, more potent poison ivy in the future with climate change, so it’s probably good to determine a strategy moving forward.

About five years ago, I had made an attempt to clear a space on my property beyond my fence and into a drainage ditch that was hard to reach, but getting overrun with tree-smothering vines, English ivy, and all matter of problematic brush. After several hard hours of pulling, clipping, snipping, and dragging, I declared the job done. In the next few days, poison ivy rash made its appearance up and down both arms, a bit on my legs, and even a few places on my body I must have rubbed. This took weeks to heal, and I resolved to be more careful in the future. I hadn’t even realized poison ivy was back there.

The next year, I wore pants, got better educated on how to spot it, and kept a better eye out for poison ivy while I worked on maintaining the same space. Poison ivy again got me pretty bad on the arms!

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