Making the right choices for a small yard with clay soil

Q: I live in North Tacoma in a new house, and I'm trying to get the soil in my garden areas plantable. It is very hard, compact clay. Last fall, after we moved in, I mixed in Tagro, and right now I'm using compost from the nursery. However, it's still so mudlike I'm afraid to plant anything in it!

1. Do I dare plant in this muck?

2. I was thinking of planting some vine maples next to the fence for a "screen" and shade in the summer and pretty fall color. I am also thinking of using a strawberry tree (compacta) and some conifers, though I worry about drainage.

3. My father gave me two Cryptomeria 'Sekkan Sugis' as a housewarming gift. Despite the tag information (which reads 12-15 feet tall and 6-8 feet wide), I have seen numerous in neighborhood gardens that are much larger. I think they are so beautiful but worry that they may be too much for my backyard space.

4. Can you recommend some plants that grow well in clay? So far I know of some barberries, which are quite lovely, though a bit thorny.

A: It's great you've started your new garden by improving the soil, for that will ensure your long-term gardening success. Clay soil is a challenge; it's soupy in winter and in summer dries impossibly hard. The good news is that it does tend to be nutrient-rich. To answer your questions in order:

1. Yes, you should be concerned about planting in muck, which smothers and drowns plant roots. Compost helps. For better drainage, you may need to install French drains or consider creating berms or building raised beds. These are big tasks — you might want to seek professional help. The PlantAmnesty Referral Line (206-783-9813) can help you find a landscaper experienced in dealing with drainage and clay soils.

2. Vine maples are handsome, adaptable trees, and strawberry trees (Arbutus unedo) are pretty in all seasons, but both require better drainage than the conditions you describe.

3. Golden Japanese cedars (Cryptomeria 'Sekkan Sugi') are easy-to-grow, columnar-shaped trees that need sun and good drainage. They grow slowly to 8 to 10 feet high by 4 feet wide in 10 years, maturing at 25-30 feet. Trees pretty much always grow larger than we expect, so if you have any doubts, plant the cryptomeria where you can give them plenty of space to grow into their mature size and shape.

4. While many plants grow well in clay, few can live in water-saturated soil. Perennials that tolerate clay soil include asters, coneflowers, bee balm and daylilies.

Ornamental grasses like sweet flag (Acorus gramineus), Miscanthus sinensis and Panicum virgatum grow well in clay soil. Some trees for clay soil are Norway and silver maples, aspen, cottonwood, river birch, hawthorns, lindens, willows and ginkgos; shrubs besides barberries include redtwig dogwood, snowberry, ninebark, forsythia, serviceberry, winged euonymus and sumacs.

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.