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When to Divide and Conquer

Some perennials should wait until fall

Spring fever means many home gardeners get the urge to dig in the garden and divide their perennials. Some herbaceous perennials, however, perform better when divided in late summer and early fall. These late-bloomers include hostas and daylilies.

To divide these species, wait until they finish flowering and as they start forming seeds, generally in late August and early September.

Divide these plants now and you’ll get fewer flowers and smaller plants after the first growing season. Also, it is easier to divide them in late summer as larger plants are easier to handle.

When dividing hostas and daylilies, remove the stems with seed pods. Seed production requires lots of energy, so removing these stems enables the new plants to recover more quickly and make larger plants.

Both hostas and daylilies perform best in organic-rich soils. Boost your divided plant’s growth by back-filling the planting hole with a mixture of equal parts compost and soil. The plants will grow larger leaves and crowns and produce taller flowering stems.

Hostas growing under droughty conditions — often the case as hostas can grow in the shade of other plants — will flourish in new, richer soil.

Evaluating Mulch

Q Do you have any information on the benefit of regular mulch over the new dyed mulches?

In our community, the contract calls for double-shredded hardwood mulch and the landscaper just installed a dyed product. It looks great, but I do not think it is good for the trees.

—Kevin J. McLaren, Upper Marlboro

A Dyed mulch is nothing more that ground-up pallets colored with Bayer wood die. It provides great weed control because it starves the weeds to death; it will starve to death all shallow-rooted plants and new transplants as well. I recommend that it be used only in making pathways and around well-established deep-rooted plants. Your double shredded hardwood bark is equally hazardous. Repeated applications result in toxic manganese accumulations and increase in soil pH. I do not recommend using it except for a single application at five-year intervals.

Ask Dr. Gouin your questions at [email protected]. All questions will appear in Bay Weekly. Please include your name and address.

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