Growing Concerns 552: Myrtle, thin, patchy


Changing a groundcover bed from threadbare blanket to lush quilt


Dear Janet

I read that a lot of groundcovers had a bad year, something about last winter that made it thin and patchy this year. Well, that's my bed of myrtle, which looks like a threadbare blanket where once it was lush. I tried to replant but the new plants didn't seem to take.

If I should take the myrtle out and plant something different next spring, what are my choices?


Dear F.G.,

I'm not surprised the replanting efforts failed. When plants are injured by bad weather, they're often so weak that they succumb to disease pathogens that are always around but not able to take hold on healthy, vigorous plants. Late warmth in fall 2002 followed by early, lasting cold without snow cover killed many plants and weakened others. By spring 2003 the damaged plants were sitting ducks as it became warm enough for fungi that cause plant disease to proliferate -- Pythium root rot, Sclerotium crown rot and others.

By the time it was apparent that your plants were dead or in trouble, the fungi had proliferated. Into that disease-ridden area you unwittingly put new plants which would struggle a bit even at best as they dealt with transplant shock. That was like putting healthy but jet lagged people into a room full of sneezing, coughing sickies.

This year I saw some winter-injured plants -- fragrant white hostas, blackeye Susans, ajuga -- limping along even into summer. Their gardeners were aware that they weren't wonderful but were nonetheless shocked when they suddenly collapsed and died as the going got toughest in the heat and drought of July.

Switch to a groundcover that is not related to myrtle and so is not likely to be susceptible to exactly the same fungi as have accumulated there in killing the original myrtle. You can remove what's there and plant all new, or add a second or third species to create a quilt.

I favor quilts, which have built-in resistance to bad times. In a year when species A isn't doing well, it's likely that species B or C will muscle in to fill any bare spots before weeds can take that space.

On the Internet, go to, a website developed by that master of groundcovers, Dave MacKenzie of the nursery Hortech, Inc. Choose groundcovers (or grasses, vines or ferns) and then go to the "Plant Selection Wizard" feature. Pick the buttons that describe your site's light and soil, and your preference such as bloom time, drought tolerance and attraction to wildlife. You'll be treated to a customized, illustrated encyclopedia culled from Hortech's 400 selections.

Alternately, go to a library or bookstore for David MacKenzie's books, "Perennial Ground Covers" (Timber Press) or "Premium Plants: Superior Plants for the Great Lakes States" (Hortech, Inc.). Or stop in at a garden center to ask which of Hortech's line of Premium Plants they are carrying or whether they have a catalog you can peruse. The majority of garden centers in Southeast Michigan do carry at least some of that line. Since it's slow season at the garden center, you're liable to get more help than you ask for.

Short reports

Don't worry, the plants are fine in this cold.

We're bundled against the coldest weather we've had in a while but so are the plants, muffled in an insulating layer of snow. Besides, this isn't severe cold for zone 5 plants. If the plant is hardy to zone 5 then it's capable of surviving that average minimum winter temperature expected in zone 5, twenty below zero.

Three cheers for that groundhog!

You don't put much store in a groundhog's reaction to his shadow? I hold the date in high regard! The sun's higher and days are longer so light is stronger now. That combination stirs plants at a cellular level, changing internal chemical mixes to rev up for spring.

You may not be able to see trees' buds swell or buried crowns of perennials start to grow but you'll see the February effect if you keep an eye on your houseplants. Soon after Groundhog Day they'll kick into a higher gear to push out new growth or flowers. Outdoor critters sense the change too, and begin to shake off their winter torpor. Odd as it seems, I am thrilled each February to catch my first whiff of skunk, because that animal's stirring is another confirmation that the big chill is ending.


Green thumbs up

to vegetable growers already planning their planting and arranging to share their harvest with people in need. You can donate vegetables, too. Search the internet for details of programs in your area.


Green thumbs down

to sitting still and getting soft! Take a walk in the woods, go stroll in a nursery's greenhouse or botanical garden conservatory, patrol your yard to pick up windblown litter, or shovel walks for neighbors. Or put a couple dozen seed catalogs under each arm and do laps in your family room. You need to stay in shape for the gardening season!

 Originally published 1/31/04