Q: I haven't done a lot of pots yet, so don't know exactly how one "refreshes" the soil. What comes to mind is lifting the plant out when the soil is somewhat dry and dumping the residual soil out of the pot. And by "well draining" potting soil do you mean the type that doesn't say "holds water well?"
A: Since plants in pots are completely dependent upon that small amount of contained soil, it should be "refreshed" at least once a year.
If your plant is in a roomy pot with lots of soil around its roots, or if the plant is one that likes leaner soil, such as a phormium or rosemary, then you can simply skim off a few inches of old soil in early spring, leaving room for replenishment. Then add several inches of a good quality soil mix and water in thoroughly.
For greedier plants, such as clematis, hostas, roses or hydrangeas, or in situations where you're expecting a plant to live in a fairly small amount of soil, then it helps to carefully dig out around the roots a bit, pouring in as much fresh soil mix as possible.
It doesn't hurt to add compost and some composted manure in with the soil to feed the plant and improve the soil. As you suggest, you could very carefully lift a plant out of the pot, tap it gently to dislodge some soil, and tamp it back in surrounded by fresh soil.
For a plant to live happily in a pot over many years you need to root prune every few years. After you've lifted the plant out of the pot, trim its roots a bit, which allows even more space for fresh soil.
When choosing potting soil, avoid formulations that hold water (these are for fuchsias and other annual plantings) and make sure the mix includes organic matter and some amount of perlite, which lightens up the mix and helps drainage.
Q: Is it time to prune roses? I read to cut them back in February, but it seems so cold for that now.
A: Around March 1 is the ideal time for rose pruning. For many gardeners, tidying up the rose bushes is the first task of the year, ushering in the new gardening season. For expert pruning tips, join the Seattle Rose Society for a demonstration of rose pruning noon to 2 p.m. Feb. 25 at the Woodland Park Rose Garden. Fred Dahl, 206-938-4350, has more information.
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.
