Extension News: Landscaping Archives

Spring is finally here. The days are longer and warmer, daffodils are popping up, and the mulch volcanoes are erupting.

The mulch volcanoes? You know, those piles of bark mulch mounded up beneath many landscape trees. I don't know where or why this practice started, but too much mulch under a tree or shrub actually does more harm than good, and is a waste of mulch and money.

Mulch serves several purposes besides dressing up your landscape. It helps retain soil moisture, important because most "feeder" roots (the roots that obtain water, air and nutrients for the tree) grow in the top 12 inches of the soil.

Mulch that's deeper than three inches can smother feeder roots and compromise the tree's health. Roots may actually grow up through a too-thick mulch past the base of the tree and encircle the trunk, a condition called girdling. As the tree grows, these roots could choke the tree and cause a slow death.

Mulch should never touch the trunk of the tree. Because it holds moisture, mulch will keep the trunk damp, encouraging bark rot and disease. Also, insects and rodents may find homes in the mulch volcano and feed on the bark of the tree.

Spread the mulch in a uniform layer two to three inches deep and out at least to the drip line (the area beneath the outermost branch tips of a tree). You want the natural flare at the base of the trunk, where it meets the ground, to be exposed. You can renew mulch each year by adding a little to the surface; there's no need to remove old mulch, but don't allow it to become deeper than four inches.

Because mulch helps prevent roots from drying out, especially when newly planted, use a quality, natural mulch. Untreated plant-based mulches are best, since they help improve the soil as they decompose. These include wood chips, bark mulch, straw, leaves, and pine needles. Avoid wood-chip mulches made from construction materials, pressure-treated lumber and old telephone poles, as these might contain harmful chemicals.

Mulch can also prevent weeds from growing around the base of the tree. Particularly when the tree is growing in a small or confined area, unwanted plants (or even flowers) may compete with the tree or nutrients and water.

Finally, mulch provides a "safe zone" between your lawn and the tree. This makes lawn mowing easier, and protects the bark from mower or trimmer damage.

If you'd like to remove the mulch volcano from your tree, do it gradually over a few months. The trunk has been kept shaded and damp from the mulch, and sudden exposure to the sun could cause it to crack. If the feeder roots have grown up through the mulch, they could dry out and lose their ability to absorb water. Remove the mulch a little at a time, remembering to water the roots thoroughly for 20 minutes each time.

You may lose some roots to exposure during this process, but in the end your tree will benefit from having deeper roots and a healthier growing environment.

By Melinda Wright, Cooperative Extension Master Gardener and Tree Steward

Photo: the Plant & Pest Diagnostic Laboratory at Purdue University Used with permission.

Lift your spirits and welcome spring with a visit to the UNH Greenhouse Open House, Friday, March 28 and Saturday, March 29 at the UNH campus in Durham.

The greenhouses will be open from 9 a.m. until 4 p.m. both days, and there's no admission charge. You'll find plenty to do and see.

• Take a guided tour.
• See UNH research projects and a breathtaking array of plants.
• Bring your gardening questions to an Ask-the-Experts session.
• Bring your sick houseplants in for diagnosis.
• Shop for plants and flowers.
• Join a question-and-answer session on carnivorous plants.
• Attend talks by UNH faculty on topics such as eco-friendly insect control on home lawns, new and different vegetables for the home garden, shoreland landscaping, and more.
• Have lunch in the Greenhouse Cafe.

The UNH greenhouses are located off Main Street in the west end of Durham. For more information about the Greenhouse Open House, call 862-3200 or view the brochure.

This spring about 1,000 New Hampshire landowners will slice the newly-defrosted ground to create thousands of welcoming holes for tree and shrub seedlings bought from the State Forest Nursery.

Howie Lewis, nursery forester, calls his nearly 40-acre nursery one of New Hampshire's best- kept secrets. Lewis says the nursery produces a unique product.

"We provide something nobody else does – tree and shrub seedlings native to New Hampshire, with seeds picked from specimens grown right here in the state. When you buy from the state forest nursery, you know the plant is suited to grow here."

A century-old enterprise
In operation in Boscawen since 1910, the nursery grows more than 50 species of trees and shrubs for reforestation, Christmas trees, and wildlife, and sells them at affordable prices. Seedlings, sold on a first come-first served basis, include conifers such as white, red and Scotch pine, Norway, blue, red, and white spruce, concolor, balsam, fraser and douglas fir, and hemlock.

The nursery offers many deciduous species as well, including arrow-wood, crabapple, fragrant sumac, grapes, highbush cranberry, dogwood, rose, nannyberry, beach plum, elderberry, winterberry holly, bayberry, hazelnut, red oak, cedar, sugar maple and white ash.

Special deals
Special "packages," each containing an assortment of 25 shrubs and/or trees, include a Christmas tree sampler, as well as wildlife-and-songbird, wetlands, native species, and winter survival packages.

"This is a very popular program," says Hillsborough County Cooperative Extension Forester Jon Nute. "The seedlings are usually two to four years old, up to 24 inches tall, including the roots, and you can easily hold about a dozen in one hand."

"Some first-time buyers come expecting to pick up large potted landscape-type shrubs and are a little shocked when you hand them a bundle of 50 pine seedlings that can easily fit into a shopping bag," says Nute. "However, these small seedlings are hardy and easy to plant and just great to use in reforestation projects, windbreaks, and Christmas tree plantations."

Ready to order?
Individuals can order seedlings from January 1 through March 30 each year in quantities of 10, 25 or 100 per bundle, with costs ranging from 25 cents to $1.00 per seedling, with the seedlings distributed for planting at the end of April.

"When you're in the nursery business, spring starts a different time each year," says Lewis, "So we ship to a county pickup point in late April or early May, whenever the seedlings can be lifted from the ground. We work throughout the year getting ready for the spring shipment and hope we have many new customers this year." Customers receive a card in the mail announcing the pick-up dates.

Order early! We've just let New Hampshire's best-kept secret out of the bag.

By Karen Bennett, UNH Cooperative Extension Forest Resources Specialist

More information:

• View the State Nursery catalog and order online.


• To receive a catalog, contact the N.H. State Nursery, N.H. Division of
  Forests and Lands, P.O. Box 1856, Concord, NH 03302-1856, or call 603-271-3456.


• Planting and Care of Tree Seedlings


• Establishing the Christmas Tree Plantation

A new way of thinking about landscaping home grounds and public spaces

New Hampshire's rapid development over the past four decades has replaced natural plant and animal communities with landscapes that often appear as an afterthought, replicating the same few plants over and over again," says Mary Tebo, UNH Cooperative Extension's community forestry educator.

"This cookie-cutter approach weakens natural communities, reduces plant and animal species diversity, degrades soils and water quality, and destroys the look and feel of the land that form our sense of place. Another result of disturbance is proliferation of invasive plants that crowd out native plants and imperil endangered species. Invasives alone cover more than 100 million acres across the nation and cost U.S. taxpayers billions."

Looking to nature for guidance

"But what if we looked to New Hampshire's natural ecosystems for guidance? By following nature's lead we can create landscapes and gardens that not only add beauty and increase property value, but that also protect soils, promote species diversity, reduce pollution, minimize energy and labor costs, recycle wastes, support the local economy, and look and feel as if they belong in New Hampshire.

"That's the approach we take in our new book, Integrated Landscaping: Following Nature's Lead," says Tebo.

"Integrated landscaping features multi-layered plant systems that grow and change over time," she says. "It proceeds holistically. Every step in integrated landscape, from initial conceptual design, to plant selection, establishment and ongoing maintenance, anticipates or loops back to connect with every other step."

Besides Tebo, the book's authors include landscape designer and permaculturist Lauren Chase-Rowell, geographer and low-impact living advocate Kate Hartnett, and professional artist and teaching naturalist Marilyn Wyzga. The idea for the book emerged after a conference where the four women got to talking about the need for information that would help landowners faced with challenging environments such as wet or droughty areas or small, tight spaces make environmentally sensitive decisions about landscaping.

A grant from the N.H. State Conservation Committee (the "moose-plate" fund) got the book project underway.

A book anybody can use: homeowners, professional landscapers, municipal planners and community developers

"We've created a book anybody can pick up and create a beautiful, multi-functional landscape, whether their space is a postage-stamp garden, a parking lot island, a municipal park, or a large backyard," Tebo says.

"We invite readers to take a fresh look at their existing landscapes by asking questions such as: How does it follow nature's lead already? Does it keep soils covered? Are there any invasive species present? Are any plant layers missing? Plants that provide food or homes for wildlife? Can an individual tree or shrub become the foundation for a multi-layered plant system?"

Lavishly illustrated, Integrated Landscaping features original photos, drawings, and sketches on almost every page to provide clear examples of the concepts presented. The book also incorporates 12 plant-system models that help landscapers and gardeners apply the concepts of layering and visualize how plants can work together in a variety of different low- and high-stress settings.

Integrated Landscaping provides extensive plant selection charts and lists, worksheets for completing a comprehensive site inventory, plus appendices that offer more information on the many topics presented.

The 162-page book costs $20, plus $4 shipping and handling for mail orders

Order online

Peek inside Integrated Landscaping: Following Nature's Lead

I brushed a mere dusting of snow off the car when I left that parking lot south of here. Suddenly it was coming down real hard and blowing right straight into the windshield, getting harder to see the road.

Lowering the sun visor seemed to help a little. Should've wiped clean the headlights before I left. Too late now. I think I'm still on the road, hard to tell though, I might be edging into that cornfield. No pull-off plowed out yet to let me pull over. Not sure I would anyway.

That character is following so close he'd probably plow into me if I stopped. Guess my tail lights are his security blanket or something. Holy smokes, buddy! Back off a little!

Keeping winter roads open: expensive
White-knuckled driving. If you've lived in New Hampshire for any time at all, you've experienced it. It's a common occurrence in all northern parts of the U.S., particularly those flat open regions of the West and Midwest. Staying on top of wind-blown, drifting snow is a constant chore for plow drivers, and snow removal costs can run pretty high.

A while back a county in Idaho kept track of what it cost to keep open a two-mile stretch of road. It ran upwards of $20,000; that was back in the 1990s, with lower fuel and other expenses than today. Their solution, with an eye towards both lower expenditures and improved driving conditions, was to plant a "living snow fence" the next spring.

Utility of living windbreaks
Call them what you like: windbreaks, shelter-belts, living snow fences, these plantings are popular in many parts of the country. Done right, they're more than just a haphazard line of shrubs and trees. In a properly constructed windbreak, careful bio-engineering considers design, location and plant species selection to achieve the intended results.

Like a structural barrier, a windbreak works by slowing down wind speed, causing the snow to settle out of the air into a designated area away from buildings and roadways. Long-lived plant barriers also offer a lot of other benefits. I think they have a place on many farms and rural homesteads.

Wind makes it worse
Wind exaggerates normal weather conditions, making everything a good bit harder to do. A glance at wind-chill charts illustrates that pretty well. Air temperature zero degrees? Add a 20mph wind to that and it's now 39 below. Add snow and you've got a double whammy.

Dense, multiple-row windbreaks can pile up snow where you want it. Somewhat like a sheltered deer yard. Lower-density field breaks can be used to uniformly spread snow over a larger area.

Grow your own
The materials for constructing these are easy to obtain (see article on State Forest Nursery) and could already be growing on your property. Besides buffering winds, these living screens can screen and soundproof unattractive or noisy areas, improve wildlife habitat, possibly even add extra income from agro-forestry products.

Learn more about windbreaks

by Steve Turaj, Extension educator, Coos County

The calls started coming into the Family, Home & Garden Education Center in mid-May: Help, all my plants are dying! My landscaper spread mulch around them yesterday and today they are scorched, wilted, and some are losing leaves. Besides that, my lawn is yellowing alongside the mulched bed. What can I do?

Known as sour mulch, this problem occasionally shows up when hardwood mulch has been stockpiled in very large piles. High moisture and lack of oxygen towards the center and bottoms of these piles leads to anaerobic fermentation, producing by-products such as alcohol, ammonia, and organic acids that can harm plants. Storing mulch in long, low rows no more than 10 feet high and turning it frequently to expose it to oxygen will keep it from souring.

Once sour mulch is spread, plants show symptoms within a day. Sometimes they recover and other times they die. A wide range of plants, from herbaceous perennials and annuals to newly planted trees and shrubs, can be affected.

Often you can detect sour mulch by its rotten-egg, vinegary, or ammonia-like smell, although these odors dissipate quickly once spread out. It may also feel hot to the touch. The pH is very low, ranging from 2.2 to 3.5, a good diagnostic test if you suspect you have sour mulch.

Damage is quick but not long-lasting. The harmful compounds in the mulch will volatilize and/or leach out fairly quickly once the mulch is spread in a shallow layer. Landscapers who suspect they have piles of sour mulch should check the pH and, if in doubt, spread the mulch and turn it to provide aeration. Apply lots of water to leach out the toxins and apply an ample amount of lime to bring the pH back up. After a few weeks, the mulch should be safe to use.

Homeowners shouldn't buy, spread or allow application of mulch with off-odors or mulch that's hot to the touch.

Interestingly, the sour mulch occurrences this year were limited to black mulch. Of all the calls received by Cooperative Extension or the N.H. Department of Agriculture, Markets & Food, no one complained about problems with other colored or natural mulches. We were not able to trace the black mulch back to a common source, however.

by Cathy Neal, UNH Cooperative Extension nursery and landscape specialist

For more information:
Beware of Toxic Mulch
Beware of Sour Mulch
Sour Mulch

A manual for N.H. Landowners and Landscapers

No matter where you live in New Hampshire, the actions you take in your landscape can have far-reaching effects on water quality. Why? Because we all live in a watershed, an area of land that drains into a surface water body such as a lake, river, wetland or coastal estuary.

Landscaping at the Water's Edge: An Ecological Approach, a new book from UNH Cooperative Extension, explains how landscaping choices affect ground water and demonstrates how, with simple observations, ecologically-based design, and low-impact maintenance practices, you can protect--even improve--the quality of our water resources.

"Every citizen should be concerned with the impact of his or her own actions on the environment," says Extension landscape specialist Cathy Neal, one of the book's authors. "The balance of nature is easily disrupted by humans, with far-reaching impacts on water quality, soil health and stability, animal and human health, and the living ecosystems around us."

"This book will help you understand the basics of how watersheds and shoreland ecosystems function so you can use the strategies and techniques presented to help prevent soil erosion, nutrient and pesticide runoff, exotic plant invasions, and other detrimental processes associated with developed landscapes," Neal says. "Applying the principles of ecological landscaping will support wildlife and plant diversity and maintain or even improve water quality in our lakes, streams, rivers, bays and estuaries."

In addition to Neal, the book's authors include nine other UNH Cooperative Extension educators with expertise in horticulture, soils, water resources, entomology, turf grass and landscape maintenance. These educators partnered with an ecological landscape designer and consulted with state regulatory agencies to provide the most current information to help landscapers and property owners make good decisions about landscape inventory, design and maintenance practices that will protect water quality in our lakes, ponds, rivers and estuaries.

Illustrated with full-color photographs, paintings and drawings that provide clear examples of the concepts presented, Landscaping at the Water's Edge: An Ecological Approach also contains appendices that include relevant information about state regulations, recommended plant lists and other resources.

Order your copy online.