Master Gardeners: Mulches vary in composition and look, but none is 'best'
BY BRIAN JERVIS Ask a Master Gardener
Saturday, December 08, 2012
12/08/12 at 4:16 AM
Q: I am going to mulch my trees; which is the best type to use? Bob, Tulsa
A: Mulching plants is one of the key elements in plant care. There are many different types of mulch, but there is no "best" one.
There are two categories of mulch - organic and inorganic. Some examples of organic mulches are shredded tree barks, wood chips, leaves, hay and straw, pine needles, grass clippings, and pecan shells. Inorganic ones are gravel, plastics and shredded rubber tires.
There are numerous advantages of using mulches. All mulches moderate temperatures, conserve water and promote air flow over root zones. During the summer, soil may be 20 degrees cooler - and, in winter, several degrees warmer - than unmulched areas.
Mulch also blocks the harmful effect of grass and weeds on the roots of young trees. Trees undergoing establishment may grow up to three times faster and have bigger root systems when mulched.
Organic mulches benefit the soil itself by releasing nutrients and organic material into the soil as they decay. This reduces soil compaction and crusting, making it more plant friendly. A big benefit of all mulches is that they prevent damage to tree trunks with lawn equipment.
When do you mulch? It is a good habit to mulch new plantings as soon as they are in the ground. For existing plants, a general rule is to apply after the first couple of freezes and in the spring after the ground warms.
Some people are concerned about mulches possibly causing chemical changes in the soil, such as adding to soil acidity. This doesn't happen. No mulch, including oak leaves, will acidify the soil. Another concern is that as mulch decomposes it will take all of the nutrients from the soil. While the microorganisms causing wood decay require nitrogen, they don't extract it from the underlying soil at any significant depth and, after decay, end up adding nitrogen and other nutrients to soils.
An often overlooked mulch source is shredded landscape waste from the city's Green Waste Site. This mulch is free if you show proof of residency in Tulsa. The site is on 56th Street North, just west of Highway 169, and is open daily from 8 a.m.-4 p.m., except on city holidays.
If you have a garden-related question for the Master Gardeners to answer in a column, call 918-746-3701.
Original Print Headline: No mulch stands out as the best
Keep all plants watered even though some may be dormant. We are still far behind in needed rainfall. Don't neglect those plants under the eaves of a house that receive no precipitation.
Irrigate all plantings at least 24 hours before hard-freezing weather if soil is dry. Try to water deeply; shallow roots do not absorb water as well as deeper ones during freezing temperatures.
Wrap young, thin-barked tree trunks with commercial protective material to prevent winter sun-scald, which causes fissures in the bark.
Christmas gift ideas for the gardener might include tools, garden books, magazine subscriptions, Oklahoma Gardening educational tapes or a membership to Oklahoma Botanical Garden & Arboretum.
Mulching moderates temperatures, conserves water and promotes air flow over root zones. BILL SEVIER/Courtesy