The What, Why, When and How of Mulching
By Julie Abramson, Master Gardener
Mulching garden beds can often make the difference between success and failure, especially when gardening on dry sites or with newly planted perennials, shrubs or trees. Some plants that are marginal for your climate zone may also thrive in your garden with winter protection through mulching. Mulching is one of the simplest and most beneficial of gardening practices.
What is mulch?
It is a protective layer of material, often organic in nature:
- Grass clippings
- Bark chips
- Shredded bark
- Leaf mold or decomposing leaves
- Cocoa or buckwheat hulls
- Shredded leaves
- Pine needles
- Christmas tree boughs
Such material is laid down on exposed soil in the garden and spread to a depth of 2-4 inches. Mulch can also be inorganic, including stones, stone dust, landscape fabric and plastic sheeting.
Organic mulches ...
- enrich and protect the soil from erosion
- reduce compaction from the impact of heavy rains
- conserve moisture
- prevent weed growth
- keep soil cooler in summer and frozen in winter (see ‘when to mulch’ below for explanation of why it is important to keep the soil frozen in the winter)
- keep fruits and vegetables clean and keep soil-borne disease from splashing onto plants
- set plants off visually and give garden a finished look
- improve the condition of the soil by providing organic matter from decomposing mulch
- improve root growth and the infiltration and water-holding capacity of the soil
- provide source of plant nutrients and encourage earthworms and other beneficial soil organisms
Inorganic mulches can do some of the same things that organic mulches do, such as keeping weeds down and protecting soil and plants; however, they do not enhance the soil, provide nutrients to plants or improve the look of the garden, with the exception of stone mulches.. Stone mulches can be very effective in rock gardens both visually and as a protection from rot for sedum, cacti and other rock garden plants. Plastic mulches offer some advantages for the vegetable garden as they warm the soil and keep warmth-loving plants such as tomatoes, peppers and eggplants happier in our northern climate. Recent research has shown that red plastic mulch improves the productivity of tomatoes. Salt marsh hay and straw work well in the vegetable garden while other types of hay may harbor weed seeds. Shredded leaves are an excellent mulch for perennial beds, as is shredded bark, while bark chips and shredded bark are effective in foundation plantings or around bushes or trees.
When to mulch?
Time of application varies with your goal in mulching. Mulches provide an insulating barrier between the soil and the air and moderate the soil temperature. Therefore, a mulched soil in the winter may not freeze as deeply as one that is not mulched. Yet, mulch also will cause soil to stay frozen when warm spells occur in the winter, thus protecting your plant roots from exposure due to the heaving resulting from freeze and thaw cycles. This is a major cause of plant loss in the garden. Although it may seem counter-intuitive, when you mulch to protect plants from the impact of winter, you are actually trying to keep them consistently cold rather than warming them with the mulch. Therefore, it is essential to wait to mulch plants for the winter until the ground is fully frozen. In our area, that may vary with the weather but often coincides with the post-Christmas disposal of Christmas trees whose boughs serve as an excellent mulch for the perennial garden. In my last garden, I was able to convince the town waste collectors to drop a load of Christmas trees at my door when they were collecting them for recycling. It is important to note that if you apply mulch before the ground has frozen, you may be offering rodents an attractive spot in which to over-winter and possibly munch on the bark of trees or shrubs. Mulching around trees also can protect them from weed whackers and mowers.
However, since mulch insulates, mulched soils warm up more slowly in the spring than soils that are not mulched. Therefore, you should not apply mulch in the vegetable garden until the soil has warmed. In fact, you can use plastic mulch to hasten the warming of the soil for those vegetables that appreciate warmth but not for those such as peas or lettuce that need cooler soils. Wait to add mulch to existing perennial beds until the soil has warmed fully.
How to Mulch?
- Remove weeds before spreading mulch.
- Keep mulch at least 6 inches away from the trunk or a tree of shrub to avoid build-up of moisture and provision of cover for rodents
- Do not let mulch come in contact with the crowns of plants
- Add no more than 2-4 inches of mulch
- Avoid mulch build-up beyond 2-4 inches especially around trees; build-up can reduce oxygen available to the roots of plants and trees
- Put down five layers of newspaper or a layer of cardboard when starting new beds; this suppresses weeds initially and adds organic matter to the soil as it rots
- Purchase mulch by the yard if you have a large area to mulch or by the bag at garden centers if your area is small
Declare Independence From Weeds
Contributed by Jennifer Tufts, Master Gardener
July conjures up images of hot, lazy days in the sun, juicy watermelons, ice cream, fireworks, and summer flowers. Most of the serious planting work is done. Now it's time to sit back and enjoy the long days, harvest the fruits of our labors, watch the fireflies, and, of course, pull the weeds.
Thoughts of Fourth of July celebrations inspired this Master Gardener to look into our country's ecological history. On Independence Day, Americans remember a victory that seems long behind us. But, in fact, we are standing side by side with Paul Revere and the Minutemen of the Revolutionary War every time we weed the garden. You may not need to be on the watch for Red Coats coming over the hill with loaded muskets, but remnants of that invasion still linger in our countryside.
In 1778, General George Washington, based in Brunswick, N. J., directed his army to put "green boughs" in their hats, issued them a double allowance of rum, and ordered a Fourth of July artillery salute to commemorate Independence Day. What he probably could not imagine was that long after the English troops surrendered at Yorktown in 1781, their ecological allies would continue to occupy and dominate North America. You might very well see many of the same green boughs George Washington was familiar with out your back door or on a walk in the Erving or Quabbin state forests. You will also find plants that arrived with the wave of European colonists - and some that have traveled from distant parts only recently.
In his book, “Ecological Imperialism: The Biological Expansion of Europe, 900-1900”, Alfred W. Crosby makes the case that European migration took many forms: human, microbial, and biological. With European domination came the advances of agriculture, including concentrations of plants and animals that brought with them populations of predators, including insects (mosquitoes!), fungi, bacteria and viruses. Crosby notes that there were "three kinds of life forms that often passed over the seams of Pangaea and usually prospered in the colonies, not with, but often without help and even despite European actions: weeds, feral animals, and pathogens associated with humanity." "Sixty percent of the more important farmland weeds in Canada are European. Of the 500 equivalents in the United States, 258 are from the Old World, 177 specifically from Europe." What more proof do you need?
William Cronon writes that "Grazing animals were among the chief agents in transmitting to America one of the central - albeit not applauded - characters of European agriculture: the weed." Ragweed was already here and we can only hope it gave the British soldiers a bad case of hay fever ... but 22 European weeds came on the scene as early as the mid-1600s: dandelions, chickweed, Shepherd's purse, bloodworts, mulleins, mallows, nightshades and stinging nettles, to name a few. "With fences had come the weeds: dandelion and rat alike joined alien grasses as they made their way across the landscape."
So, a weed is a weed is a weed, right? Not so fast. There are weeds and then there are dangerous weeds! All weeds are characterized by their ability to produce large numbers of seed as well as their adaptability, meaning that they can withstand high or low temperatures and long periods of drought. They also reproduce with a vengeance, both by seed and by asexual means. All gardeners know the back-breaking work of hand pulling and hoeing as a means of controlling weeds, and that can certainly be effective, especially against annuals, but you may need other weapons in the battle against biennial and perennial weed invasions.
If it is a lawn you are trying to save, you might consider Carbohydrate Starvation to keep the crabgrass, spotted spurge or goosegrass under control. Every growing plant needs leaves to store carbohydrates and flourish, and if you mow often enough you will seriously limit the spread of the weeds. It's not pretty, I know, but remember, this is war. Mow and mow again, removing the seed head of your worst lawn enemies, and starve them out!
Ratcheting up the intensity a bit, there is the smothering tactic for certain unwanted intruders. Obviously, this method will not work on your lawn, but for a targeted area in the garden, between the rows of tomato and squash plants, you can stop weeds cold with ground covers, including carpet, tarps, weed fabric, paper, plywood or plastic.
Another tool in the guerrilla warfare arsenal, albeit the last resort of the weed warrior, is flaming. Beware of torching your neighbor's fences, areas of vinyl siding, mulch or dry grass in the vicinity. Basic safety regulations apply, such as keeping a safe distance from the plants you want to save and any exposed body parts. But don't hesitate to do what you have to do, patriots! This is not just about ugly - this is about the integrity of our countryside!
Because this is the third century of the struggle, after all, we do have some highly modern weed control substances to recommend. There are brand new herbicides containing vinegar (yes, vinegar!) to control Canada Thistle seedlings. Other modern organic products useful for spot treatment of weeds are made from yucca extracts, acetic acid and/or lemon juice. Corn gluten meal contains a compound to inhibit germination and can take out 50%-60% of the vegetative varmints in the first year, 80%-90% by year three. Don't hold back. Throw the whole kitchen cabinet on the problem if that's what it takes!
If you want to do something a little less violent than throwing vinegar on the ground to win the war of European aggression, let me suggest that you visit Nasami Farm or the internet to learn more about our region's native plants. A native plant is generally understood to be any plant that existed here in Western Massachusetts prior to the arrival of Europeans. Whereas only 3%-4% of non-native species of plants are likely to become a nuisance by displacing native plants or endangering wildlife with a loss of shelter or food, there are several unwelcome invasives around, and we need to watch that we don't contribute to the problem by encouraging them. Unfortunately, some well-known and all too common plants, such as Norway maple (Acer platanoides), multiflora rose (Rosa multiflora), oriental bittersweet (Celastrus orbiculatus), and burning bush (Euonymus alatus) are in this category.
We are fortunate to have Nasami Farm in our neighborhood. A venture of the New England Wild Flower Society, located in Whately, Massachusetts, Nasami Farm is devoted to the propagation of and education about native plants. You can also learn about which plants are invasive non-natives and how to avoid or remove them from our ecosystem.
As you stop to honor our country's origins this year, reread the Declaration of Independence with the eyes of a gardener and see what jumps out.
When in the course of human events, it becomes necessary for one people to dissolve the political bands which have connected them with another, and to assume among the powers of the earth, the separate and equal station to which the Laws of Nature and of Nature's God entitle them. . .
Be a true patriot this Fourth of July: plant something native into your landscape and stomp on a weed.
“Changes in the Land, Indians, Colonists & the Ecology of New England” by William Cronon
“Ecological Imperialism: The Biological Expansion of Europe, 900-1900” by Alfred W. Crosby
Last Month's Feature Article:
The Red Menace: The Lily Leaf Beetle
Contributed by Lyssa Peters, MG
My mother had a unique way of controlling the Japanese beetle population on her roses. She’d send whichever grandchild happened to be around out into the yard with a jar of ammonia. The going rate was a nickel per bug caught and drowned in the ammonia.
Most gardeners are familiar with the Japanese beetle. These colorful metallic green beetles have voracious appetites and make lunch out of some of our prettiest flowers, like roses, often devouring rosebuds before they open.
A close cousin, the Asiatic beetle, is a less pretty bug (it is tan with darker spots) but also a voracious pest. Another relative lives in my garden and comes out to eat at night. It took me years to figure out who was eating my plants, since I never saw the culprits. I finally had to go out with a flashlight to see the mahogany brown beetles munching away. These guys are FAST, too, and hard to catch.
Luckily, I do not have a big problem with beetles. I don’t use pesticides, but I grow plants that attract beneficial insects. I keep my garden watered and healthy. Stressed plants attract bugs like a magnet. And I hand pick any that I see. I also do not grow a lot of roses or Shasta daisies, which are delicious and attract beetles.
If you grow asiatic or oriental lilies, you may have had some experience with a somewhat newcomer to our region, the lily leaf beetle. This bright red bug has a voracious appetite for lilies and can strip a plant of its foliage in no time.
According to the University of Rhode Island Plant Science Department fact sheet, the lily leaf beetle, native to Europe, was discovered near Montreal, Canada in 1945. Its damage was limited to the Montreal area for decades, but recently it has spread to the south and west. The beetle was first officially sighted in Cambridge, Massachusetts in the summer of 1992. The beetles are strong fliers and excellent hiders. They have spread as much as 150 miles from Boston, in many cases with the assistance of gardeners. At present the infested area in the USA reaches into all of the New England states, including southern Connecticut and northern Vermont. Not all areas are yet infested and gardeners who are transplanting bulbs and other garden plants should be careful not to move these beetles to an uninfested area.
Lily leaf beetles will taste or feed lightly on many plants including Lilium spp., Fritillaria spp., Polygonatum spp. (Solomon’s seal), Solanum dulcamara (bittersweet nightshade), S. tuberosum (potato), Smilax spp., Nicotiana spp. and other plants. However, they will only lay eggs and develop on Liliuim species (Turk’s cap lilies, tiger lilies, Easter lilies, Asiatic and Oriental lilies), and species of Fritillaria.
The lily leaf beetle adult is a striking insect with a bright scarlet body and black legs, head, antennae, and undersurface. The adults are 6 to 9 mm (1/4 to 3/8 inch) long, and they will squeak if they are squeezed gently--a defense mechanism to deter predators. Adults and older larvae feed on leaves, stems, buds, and flowers of the host plant. Adults lay their eggs on the underside of leaves in an irregular line. The reddish/orange eggs take from 7-10 days to hatch under normal conditions. Females lay up to 450 eggs, sometimes over two growing seasons. Larvae resemble slugs with swollen orange, brown, yellowish or even greenish bodies and black heads. Larvae tend to cause more damage than adults. Larvae are distinctive and repulsive in that they secrete and carry their excrement on their backs. Younger larvae feed for 16-24 days, primarily on the underside of leaves. Larvae enter the soil to pupate; pupae are florescent orange. New adults emerge in 16-22 days and feed until fall. They do not mate or lay eggs until they emerge the following spring in late March through June. Lily leaf beetles overwinter in the soil or plant debris in the garden or woods, sometimes a distance away from the host plants. Adults prefer environments that are shaded, protected, cool, and moist.
If you spot Lily leaf beetles on your lilies, don’t wait to see if they will disappear on their own. Immediate action is necessary.
Here is some excellent advice I found on ivillage garden web:
First of all, if you’re in an infested area, avoid sending any lilies or other plants to anyone else, and carefully inspect any plants you receive.
Hand-picking should be the first level of control if possible. Constant vigilance and quick removal and disposal of beetles, eggs and larvae can control an infestation on a small number of plants. Make sure the critters are actually dead! If you squash them, don’t leave the squashee in the garden. Some gardeners drop them into a can of water with vegetable oil on the top. If you suspect the beetles may be lurking around your lilies but you don’t see any, carefully dig in the top half inch of the soil - no deeper! They hide just under the surface, so be ready to get them when they pop out.
The adults are easily spooked when you try to pick them by hand, and if you “miss” them, they tend to drop to the ground where THEY LAND UPSIDE DOWN, and since their tummies are black, they effectively vanish. The suggestion was to place a light-colored cloth under the plant before you hand-pick in order to be able to see the nasty little things if they fall.
If your garden is overrun with the beetles and hand picking has not gotten rid of the beetles, the University of R.I. fact sheet suggests treating flowers with neem, an insecticide based upon extracts from the neem tree. Neem can be purchased at garden centers under the trade names Turplcx, Azatin EC, Margosan-0, Align and BioNeem. Neem kills larvae and repels adults. Neem is most effective on first instar larvae; it must be applied every five to seven days after egg hatch.
Click here to visit the UMass Extension service's website for their "Fact Sheet" on Lily Leaf Beetles.
Robert Frost called them "flying flowers." Artists and children delight in them and lepidopterists study them. As a gardener, I am forever enchanted by the visit of a brightly colored butterfly with its velvety wings-especially at the most unexpected time while slaving away at weeds or dividing. It's like a friend stopping by who appreciates your garden.
Fritillary upon your viburnum, like night moths visiting the nicotiana, or dragonflies and damselflies in the meadow, offer an unmistakable extra pizzazz to the garden. And they always seem to appear at that impromptu moment.
Or is it impromptu? Actually, much can be done to coax them into your garden.
A few facts: of the Insecta class and the Lepidoptera order, they form a complete metamorphosis. Approximately 200 species exist in New England, ranging from the Great Spangled Fritillary to the Eastern Tiger Swallowtail and the Question Mark. Cold-blooded, they thrive on warm sunshine and absolutely shun windy conditions.
"To attract butterflies, we need to make only relatively small changes in our current practices and styles," states Alcinda Lewis in "Butterfly Gardens," published by the Brooklyn Botanic Garden. As usual, habitat is crucial. In the wild, many clues are offered on attracting these pollinators upon which so many plants, such as milkweed (Asclepias) or Joe-Pye weed (Eupatorium), depend.
Leaving some areas undisturbed, e.g. not mowing your field, is important for the development of the butterfly's larval stages. More specifically, milkweed provides food for this instar stage of that most fascinating butterfly: the monarch. Tall grasses or a weedy patch provide a "nursery" for females seeking a safe place to lay their eggs. Of course, limiting the use of pesticides, as endorsed by IPM, is crucial.
With good sun exposure, a warm rock to rest on, protection from wind and availability of water, the home gardener can attract these wonderful creatures. A crucial ingredient for coaxing, however, is nectar-producing flowers.
To enjoy regular visits, plan a successional garden, with grape hyacinths and lilacs in spring; perennials such as Echinacea, Echinops, Rudbeckia and Monarda as well as an array of herbs (dill and parsley if left to flower will attract the black swallowtail) in summer, and purple asters in fall. Plant in clumps and at varying heights; butterflies prefer to flit about.
Shrubs such as Viburnum, Clethra, mock orange and, of course, buddleia (the butterfly bush) will both protect from windy conditions and offer nectar-providing flowers. For male butterflies, a little salt in a mud puddle is also recommended.
Where do native plants fit in here? As it turns out, most adult butterflies are not fussy. They will gravitate toward a Chinese or South African delicacy as well as any American "dish." However, for their more vulnerable egg and caterpillar stages, native plants are often essential. For example, the orange and black Harris' checkerspot caterpillars feed only on tall, flat-topped white asters, and the monarch caterpillars on milkweed.
Finally don't worry if you're singing in the garden. Along with others such as damselflies and dragonflies, butterflies are deaf. You can holler or sing and they won't budge -- an advantage to the more hushed demands of bird watching.
For more information: the Taylor Guide "Attracting Birds and Butterflies," by Barbara Ellis; "Butterfly Gardens," published by The Brooklyn Botanic Garden; and "Butterfly Gardening in New England," published by The New England Wild Flower Society and The Garden Club Federation of Massachusetts.
Why Pollinators Are So Important
Pollinators, such as most bees and some birds, bats, and other insects, play a crucial role in flowering plant reproduction and in the production of most fruits and vegetables.
Examples of crops that are pollinated include apples, squash, and almonds. Without the assistance of pollinators, most plants cannot produce fruits and seeds. The fruits and seeds of flowering plants are an important food source for people and wildlife. Some of the seeds that are not eaten will eventually produce new plants, helping to maintain the plant population.