Q: I read in your column that Sunset's Northwest editor, Nancy Davidson Short, mentioned epimediums as a favorite of hers because they're...

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Q: I read in your column that Sunset’s Northwest editor, Nancy Davidson Short, mentioned epimediums as a favorite of hers because they’re “fantastically drought resistant.”

My “Sunset New Western Garden Book,” admittedly a 1980s version, says epimediums need a modest amount of water. This doesn’t sound drought-tolerant to me. Do drought resistant and drought tolerant mean two different things?

A: The drought tolerance of any plant depends so much on soil, shade and sun, as well as on the plant’s maturity, that shades of meaning between “drought resistant” and “drought tolerant” are insignificant.

Every plant needs at least “modest” amounts of water to thrive, especially during its first couple of years in the ground.

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After that, whether a plant can make it through the summer and early autumn without supplemental water depends on if it’s planted in bright sun or has the benefit of afternoon shade; if it’s planted in rich, water-retentive soil or free-draining, sandy soil; if its roots are able to penetrate down into the ground, or if it shares soil space with big, rooty plants.

The very same kind of plant that is drought resistant in one garden may need much more water in another.

But when it comes to plants that do well with little water, epimediums are stars. These handsome, evergreen groundcovers with heart-shaped leaves and airy little springtime flowers keep their good looks year-round with very little supplementary water, even in the driest and most difficult of conditions.

You can count on epimediums persisting when planted beneath big conifers, a “drought-tolerant” litmus test.

Q: Do you know if it’s possible to purchase capillary matting (water-absorbing mats) locally? None of the large garden stores I have contacted carry them.

A: Since capillary matting is, I think, often used for green roofs, I suggest you contact the Northwest EcoBuilding Guild (www.ecobuilding.org; 206-575-2222). An association of builders, designers, trades people, suppliers and manufacturers involved with sustainable building, this group should be able to advise you.

Or check out the 2006 Green Pages Directory, a resource for homeowners, gardeners and professionals who are looking for “green” products and services.

You can download a PDF of the directory from the group’s Web site, or pick up a copy at the Environmental Home Center or Second Use Building Materials in Seattle.

Q: I read your recent article about ground covers you can walk on, and wondered if rugosa roses tolerate any foot traffic [from those who ignore thorns]. We put kinnikinnick on our parking strip [which is very sunny and dry], and like the appearance, but it gets beaten down. We thought maybe some low-growing tough roses would look good and deter the trampling. What do you think?

A: I think you probably need some clearly defined pathways through your parking strip to save your plants. Perhaps some stepping stones would do the trick, as they’d define planting areas as well as encourage people and dogs to stay off the plants.

I’ve seen many parking strips where gardeners have mounded the soil slightly to improve drainage and discourage foot traffic, creating paths between the mounds.

Rugosa roses are tough enough for parking-strip plantings, and thorny enough to discourage anyone, canine or human, from stepping on them.

Hardy and fragrant, with handsome crinkled leaves and showy autumn fruit, rugosas are the most disease-resistant of roses. But some can grow into very large shrubs; be sure and look for the shorter kinds, such as lavender-pink ‘Fru Dagmar Hastrup,’ the double, mauve ‘Dart’s Dash’ and the white-flowering ‘Wild Spice,’ all of which grow about 3 feet high and wide.

Valerie Easton also writes about Plant Life in Sunday’s Pacific Northwest Magazine. Write to her at P.O. Box 70, Seattle, WA 98111 or e-mail planttalk@seattletimes.com with your questions. Sorry, no personal replies.