- Barbara Rainear
Answer: Classic mophead hydrangeas (hortensias) vary from pink to blue depending on soil acidity - acid for blue, basic for pink. It would appear that the soil in which yours are growing has over many years gradually lost acidity. I had the opposite phenomenon this year - about a third of a previously pink lacecap hydrangea bloomed blue. Since mine is only three or four years old, I suspect the roots, as they grow deeper, have reached a layer of more acidic soil.

What did you do wrong? Probably nothing, though any cement work nearby would do a number on the acidity of soil (a phenomenon to keep in mind for planting in general).

To get your hydrangeas back to blue, apply a bit of aluminum sulfate or iron sulfate to the soil. Dissolve 1 tablespoon in a gallon of water and apply to the soil around the plant after it has been watered. That is, do not use the sulfate solution to water the plant, for that would be the same as overdosing it. Do this monthly throughout the growing season. If you start now, you should have blue flowers next year. Rusty nails? Without getting into soil and plant chemistry, though it can work, it just takes too long. Mulching with coffee grounds, however, will provide a little acid boost, it is organic, and it takes something else out of the waste stream and makes it useful.

This Web page has good information about fun and science with hydrangea coloration: www.hydrangeashydrangeas.com/colorchange.html. The site is maintained by hydrangea enthusiast Judith King, who lives in Virginia.

Q: Some of my crape myrtles are blooming but others have not. Why?

A: Too much rain. Crape myrtles like drier conditions than we've had this summer. My 'Dynamite' (a good red cultivar) was in full bloom at this time last year, but there's nothing but foliage now. On close examination the other day, I found tiny incipient flower buds, so I expect September flowering, which will be a nice addition to the early fall garden. It seems that my plant and some of yours, with so much natural irrigation, think it's still June.

Q: I have totally lost control of my lawn. Part of it is on a decline, and when it rains, new grass seed is washed away. The rest has every manner of weed you can imagine. My husband heard about something called a "Freedom Lawn," which seems to mean basically one that is full of weeds. Is there anything we can do, short of buying lots of new sod? Is a freedom lawn a good idea?

A: Now that the crabgrass, prostrate knotweed, plantain lilies and stilt grass have reached a luxuriant level, scope out the "freedom lawns" in your area. Don't just drive by, get out and look closely, even walk barefoot if possible. Then you can decide whether this is for you. (Keep in mind that such a lawn will get freer every year, so to speak.)

For a slope where the grass seed washes away, your best bet for a traditional lawn is hydroseeding. In this process (not a do-it-yourself endeavor), a slurry of grass seed, paper pulp, fertilizer, water and a form of glue is sprayed onto the area. Absent a hurricane, it should stay in place, even on a slope, and in several weeks produce an infant lawn - those little green threads that properly watered and tended will grow into turf. The end of August and early September are the ideal time to do this.

Laying sod is not as simple as it would seem, and you rarely have any control or choice of what varieties of grass are in the sod. With a good hydroseeding outfit, you can specify what kind of seed to use. I'm a fan of mixed fescues; mature Kentucky bluegrass is too aggressive for my taste, even as part of a blend.

When engaging someone to hydroseed a new lawn, be sure to have ample discussion on site preparation (are you comfortable with herbicide to deal with those freedom plants?) and follow-up care and maintenance (for instance: failure to use crabgrass pre-emergent next April would be, ahem, a great boon to freedom).

- Michael Martin Mills