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Our Gardens as Ecosystems Part II

With Diane Greenberg

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Lovely though they are, deer are a threat to our region's biodiversity. - LARRY DECKER
  • Larry Decker
  • Lovely though they are, deer are a threat to our region's biodiversity.

Last issue, Diane Greenberg, co-owner of Catskill Native Nursery in Kerhonkson, introduced us to concepts and definitions around ecological landscaping and native plants. Let's dig deeper.

When clients have invasive plants or underperforming gardens, what do you tell them?

Frequently, when people buy a house, they feel obligated to keep the existing plants, especially if they're fairly mature. I tell homeowners not to feel guilty about editing, or even starting over. Sometimes it's easier to get rid of everything and start over with a blank canvas; other times, an older landscape plant can be happily incorporated.

We like to remove old-fashioned landscape standards like Bradford pears because they are not beneficial to wildlife and are prone to disease and storm damage. We like to replace the endless suburban rows of sterile forsythia with plants that have pollen and berries. Shrubs like barberry and burning bush are in almost every landscape and over time they've invaded our woodlands and damaged the biodiversity of our environment. Studies show they also harbor more ticks than native shrubs and should be eliminated whenever possible. 

What's your reaction to seeing things like weeping Japanese maples in Hudson Valley landscapes?

I have done Japanese-style gardens using a mix of native and non-native plants, but I tell people that a weeping Japanese maple next to their 19th-century farmhouse is going to look like a kimono at a square dance. My feeling is that I don't want to go to Japan or France and see an American style landscape—yet most Americans have acquired their garden aesthetic from Europe or Asia. We have this beautiful Catskill landscape to work with as our backdrop and we should celebrate that through our gardens. I feel we should enhance our sense of place by using native maples, oaks, winterberry hollies, red twig dogwoods, mountain laurels, and wildflowers. Our gardens should complement our region and look like they belong in the larger landscape.

What do native plants want?

As with any plant, you want to learn about the environment the plant has evolved in and then match it up to the conditions you have on your property. Ferns want rich soil in shade and huckleberries want acidic dry soil in the sun. We have a lot of high water tables in Ulster County, so we have a bog walk in the back of the nursery to show people how to create bog gardens with plants that want those seasonally wet conditions. Rocky outcroppings can be turned into alpine gardens and large swashes of former grazing lands can be biodiverse meadows, instead of something that takes hours to mow. Learn your property, embrace your site as it is, and work with nature—and you'll have a lower-maintenance garden.

One thing native plants do not want is earthworms; this is especially true for woodland wildflowers. Most indigenous worms were wiped out here during the last ice age. The common nightcrawler, Lumbricus terrestris, is now ubiquitous in America but was previously a European species never found as a native species in North America. These large worms were brought here by the settlers, who used them as bait for fishing and to add fertility to their vegetable gardens. The problem is that these worms eat what native plants thrive on—rotted leaves. Worms eat fast, while plants have to absorb nutrients slowly, so you end up with the worms beating out the plants for food. When you have large saturations of earthworms, like around lakes where people fish a lot and cast off leftover bait, you see a steep decline in the population of native woodland plants like trillium. If your soil has a heavy worm population (common on former farms) you can counteract their presence by using a lot of shredded leaf mulch. What you should not add to your native gardens is manure in any form, manure is like steroids for worm populations. 

We rarely use fertilizer, as most native plants don't need it. A common mistake when putting in a meadow is fertilizing it or using a rich soil; meadow plants are evolved to less fertile soils and thrive with some hardship. Sometimes we'll apply a little acidifier to blueberries if the soil is not acidic enough or we'll put some specific organic fertilizer around fruit trees, but for ornamentals I never use fertilizer other than that provided by the slow breakdown of leaf mulch.  

Thoughts on lawns?

Typical lawn grasses do not like our acidic soil, which was once forest floor covered with ferns and moss. I usually tell people if it's green, just mow it. In shady areas, I encourage people to let mosses, fungi, and sedges take over and then you don't have to do anything. Whenever possible, I encourage meadow plantings and garden islands to replace lawn. 

Thoughts on deer? 

People tend to have a very romantic view about deer. The problem is they are out of balance with our local ecology. White-tailed deer are more a Midwestern species, but populations were encouraged in the Northeast for hunting, and venison farms were promoted during the 1930s as an economic industry. It was not uncommon for deer to escape. These deer discovered the local corn fields and happily ate themselves into a population boom because they breed based on food supply. We have also lost our predator populations that keep the herd healthy by targeting the weak. The only real predator of deer nowadays is the SUV, especially as hunting declines.

Deer are a threat to our region's biodiversity. They devastate the forest understory by eating saplings. Without new healthy saplings to replace older trees, we will not have future forests. Deer eat the flowers that the pollinators need and the berry shrubs the birds rely upon. Unfortunately, deer rarely eat invasive plants, which helps those plants spread even faster because they are left to thrive in the environment, and also because people sometimes resort to mostly using invasive plants in desperation to have a deer-resistant garden.

For these and other reasons, I don't recommend the "deer-resistant" school of gardening to my clients. Deer are very adaptable, and when people keep using deer-resistant plants, the deer just learn to eat them—or at least damage them. Plus, for every deer-resistant plant we put in our gardens that is one less plant that would have added to the biodiversity and strength of our environment.

To deter deer, we advocate various forms of fencing, either beautiful or invisible. The nursery is completely fenced with a type of wire fencing you can't see unless you are close up. If you can't fence the full perimeter of a property, you can make a smaller fence that becomes a beautiful part of your garden. Even a small enclosure can be make a difference when it's planted with a diverse selection of beneficial plants that might be hard to grow in competition with deer. The deer just need to see some height; you don't need the Alamo. At the very least, do not encourage the presence of deer in your gardens. Chase them off when you see them. Make their habitual trails unappealing. You can detour deer with a well-designed hedgerow or by creating spaces they can't see into. Use the deer repellent sprays; they all work and it's good to rotate them. Once they're diverted to a new trail they are not as likely to pester you.

You are a superfan of opossums. Why is that? 

Unlike deer, which can spread Lyme disease, opossums prevent it by doing tick control. They're like vacuums and can consume up to 5000 ticks each. They don't get Lyme disease and they spend hours and hours grooming themselves, eating ticks. For whatever reason, ticks love opossums, and opossums love eating ticks. Leave dead trees ("snags") up on your property for possum habitat if you can. Slow down when you see them on the road and wish them safe journey to the other side.

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