Garden Detective: deadly volcano mulching

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

Jessica Damiano is a master gardener and journalist with more

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DEAR JESSICA: We have a beautiful 6-year-old weeping cherry tree. It just lost its flowers, so it appears healthy. While adding mulch to the beds recently, some of the soil was moved away from the bottom of the trunk, and we were horrified to find that at least a three-inch-high area of the front of the trunk was gone halfway through. The damage doesn't appear to be caused by insects, but we're now wondering what our options are. We'd rather not have to purchase an expensive replacement.
-- Ted and Theresa Brass, Lake Grove

DEAR TED AND THERESA: I can't be 100 percent certain without seeing the tree and the conditions in which it's growing, but it does sound like it has fallen victim to "volcano mulching."

Mulch always should be kept at least a few inches away from trunks so that the natural flare of the trunk at the soil line is visible. It never should be mounded up against a tree. When that's done -- a horrible practice referred to as volcano mulching because of the visual effect -- the portion of the lower trunk that's covered will rot, and eventually the whole tree will die. What's worse is that some "professional" landscapers apply mulch this way, lending credibility to the practice, which is then perpetuated by trusting homeowners.

I'm sorry, but it sounds like it's only a matter of time before your tree succumbs, and you'd be better off removing it altogether to avoid a dangerous situation should the tree topple on a windy day. I wish I had better news.

DEAR JESSICA: I recently purchased a few 'May Night' salvia with the understanding that they bloom spring to fall. Is that true, and is there another perennial you would recommend that blooms all summer?
-- Barry Goldstein, via email

DEAR BARRY: Salvia 'May Night' is a tough plant that thrives in full sun in practically any type of soil. Once established, it doesn't need much attention and is generally drought-tolerant. It's also a favorite of butterflies and hummingbirds, and is deer- and rabbit-resistant. However, it doesn't bloom from spring through fall, but rather from early summer to midsummer -- typically from mid-June all the way through the end of July, which is certainly a good stretch. Because of the unseasonably warm weather, this year the show likely started earlier.

Some all-season bloomers you might consider include black-eyed Susan and purple coneflowers, which start up in early July and flower straight through to fall, Knockout roses, which begin their show in spring and continue until frost, and butterfly bush, which blooms on and off all summer long. Common daylilies typically start up in July and continue through September, while the smaller, yellow 'Stella de oro' variety gets an earlier start. Consider catmint, too, which begins blooming in spring and continues intermittently through autumn.

DEAR JESSICA: I've enclosed a photo of the lovely tree fungus on my forsythia. Do you have any suggestions?
-- Jannine Thorp, East Islip

DEAR JANNINE: Those unsightly lumps are forsythia galls, which will eventually weaken and kill off branches if not treated. Although no definitive cause has been pinpointed in the horticultural world, it's believed they're most likely caused by a bacterial or fungal infection. The only thing you can do is prune off and destroy affected branches, taking care to disinfect your pruners between cuts to avoid spreading the infection.