Garden Detective: Mulching with breathing room

The practice of volcano mulching, mounding mulch up

The practice of volcano mulching, mounding mulch up against tree trunks, can lead to tree death. (Credit: Cornell University)

Jessica Damiano

Jessica Damiano, Newsday columnist Jessica Damiano

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DEAR JESSICA: I follow your monthly calendars and read that on the chore for May 30 you advised keeping mulch away from trunks and plant stems. Why? --John Stoia, Deer Park

DEAR JOHN: I'm glad you asked. The purpose of mulch is to retain soil moisture, suppress weeds and keep the soil temperature constant. When mulch is applied too closely to trunks and stems, moisture is kept in and air circulation is kept out, resulting in rotted plants.

You've probably noticed a common suburban travesty that's commonly referred to as "volcano mulching," in which 2-foot-high mounds of mulch are piled up around tree trunks for a volcano effect. The most disturbing part of this is that it's a common practice among some professional landscapers. As a result, many trees die a slow death, often several years after the offending practice, and homeowners are left wondering about the mysterious decline of their trees.

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As a rule of thumb, if you can't see the natural flare that extends from the bottom of a tree trunk to the soil line, that means the tree is, in effect, suffocating under the mulch. The buried portion of the trunk eventually will decay, and the rotting will make the tree susceptible to further disease. Certain trees will even send girdling roots into the mulch, restricting the trunk and eventually strangling themselves.

Applying mulch 2 to 3 inches deep over the root area in a circle around the trunk -- but never touching it -- will protect the tree from lawn mower injuries and provide the aforementioned benefits. More than that is harmful.

The same practice should apply to annuals, perennials and shrubs.

DEAR JESSICA: Our palm tree will overgrow our ceiling by next year. It has a wonderful shape and several offshoots. We would hate to send it somewhere with a higher ceiling. Is there any way we can prune it to a more manageable size? --Cindy and Jim McCann, Douglaston

DEAR CINDY AND JIM: Unfortunately, your palm can't be shortened, so it appears finding another home for it is your only option.

DEAR JESSICA: When you buy potted tulips, do you need to wait to plant the bulbs? The flowers have died and the foliage is withered. --Nancy Bajorski, West Babylon

DEAR NANCY: Tulips are reliable repeat-blooming perennials in Holland. But in New York, even under the best conditions, they practice what accountants call "diminishing returns" until one year all you get are stems and leaves and wonder where the party went. You certainly can plant your potted tulip bulbs now, but you should know that their unreliability is even more pronounced if they began life as a forced potted plant.

Tomato Challenge

Are you in? Mark your calendars: This year's contest will be held at 7 p.m. Aug. 23 at Newsday headquarters (235 Pinelawn Rd., Melville). Give your plants plenty of tender loving care all summer long, then bring your biggest, heaviest ripe fruit to the event. Garden Detective Jessica Damiano will weigh your tomatoes personally and crown the 2013 Tomato King or Queen.

In the meantime, send a photo of yourself with your tomato plants, along with details about your growing strategy, to jessica.damiano@newsday.com.