Question:

I live in Philadelphia and have tried growing lavender for years, all to no avail. A friend in Norristown has it happily growing in her raggedy, rocky soil. Someone told me lavender likes a Mediterranean-type environment.

- J. Brown
Answer: Mediterranean conditions are indeed key. And what are those conditions? Horticulturally speaking, they are mild, rainy winters and hot, dry summers - and good drainage. Repeat: good drainage. In addition to the Mediterranean basin itself, there are four areas that are said to have Mediterranean climates: coastal California, Chile, South Africa and Australia.

Notice that Norristown is not on the list. Which means your friend has, whether intentionally or otherwise, achieved some of the key elements. Since your friend can't change the climate, I'd say drainage and light are the magic words. Proper pruning is also important.

If you have a sunny site (five hours a summer day) that has good air circulation and excellent soil drainage and that stays relatively warm in winter, Lavandula x heterophylla hybrids can be tried (they're not reliably hardy here). For a colder site, choose an English lavender, L. angustifolia. Planting needs: neutral soil, drainage enhanced by fine gravel, soil built up 3 inches, uncrowded siting (2.5 to 3 feet from the next plant). Once established, reduce watering (think Andalucia) and avoid wetting foliage, which promotes fungus.

Pruning requirements: Once established, the plant should be modestly clipped for reshaping, in early spring just before growth resumes, then in midsummer after blooming. Do this every year, for if the lavender is happy it will probably get leggy and misshapen otherwise. Do not prune back into old, bare stems - it is unlikely to resprout - and the worst time to prune is in late fall or winter.

Q: I have a dogwood tree that I planted eight to 10 years back. It is 12 to 15 feet tall and has a trunk 3 to 4 inches wide. I now see that I planted it in the wrong spot. How difficult would it be to dig it up and move it, and when would be the best time?

- Walt Woodward
A: It would be very difficult, presuming you're thinking of shovels wielded by human hands.

If this tree has particular sentimental value, you might engage a landscaper who has what is called a tree spade. Not the kind of spade one might buy at the local hardware store, but a large mechanized attachment to a specialized tractor. This is the equipment used at tree farms and nurseries to dig field-grown specimens. Expect to pay a lot for this service - and, of course, the dogwood's current and future sites must be accessible by a tractor. If attempted, late fall, after leaf drop, or late winter, before leafing out, would be the time.

Better to purchase a new dogwood for the new site. And while you're at it, consider something other than the classic flowering dogwood, Cornus florida, which is vulnerable to an anthracnose that is marching through the woods and gardens of the Northeast. C. kousa, an Asian species that makes its show after leafing out, does not have the anthracnose problems, and some cultivars on the market are downright stunning - the tree becomes a layered blanket of white flower bracts, which last quite a while.

Kousa dogwoods typically bloom in June. North Carolina State University has a good list of cultivars at www.ces.ncsu.

edu/depts/hort/consumer/quickref/trees/dogwood-kousa.html, but don't expect to find more than a few at local nurseries. The cultivar 'Milky Way' is particularly floriferous.

Perhaps more alluring are the hybrids of C. florida and C. kousa created by Elwin Orton of Rutgers. They are increasingly available and have been selected for combining the better attributes of each species. They bloom, logically, between C. florida and C. kousa. This site describes the cultivars: www.uky.edu/Ag/Horticulture/kytreewebsite/commonnamefiles/text/cornusinfo.htm.

Send questions to Michael Martin Mills, The Inquirer, Box 41705, Philadelphia 19101 or gardenqanda@earthlink.net. Please include locale. Read his recent work at http://go.philly.com/

michaelmartinmills.