A: Wood ash has a liming effect on the soil. It can be used on any plant that is not acid-loving, but it should not be used on rhododendrons, azaleas, blueberries, cranberries and citrus fruits. Also, wood ash should never be applied where you are going to grow potatoes, as it will promote potato scab.

Don't go wild on the application of wood ash to your garden. In general, about 20 pounds per 1,000 square feet can be applied each year. (That's roughly the equivalent of a 5-gallon pail, so do measure.).Twenty pounds of wood ash.equals about 6 pounds of commercial ground limestone applied to the same area.

Note that I keep referring to wood ash. Nothing else will do. If you burn paper, trash, coal, or painted, treated or untreated lumber, you will have to find another way of disposing it.

There are other uses for wood ash, as well. It will repel some insects and slugs. If your compost is particularly acidic, with a lot of pine needles or oak leaves, you can neutralize the pile by adding a sprinkle of wood ash to each layer..

A note of caution: When cleaning your fireplace or fireboxes,.protect yourself as if you were handling any strong alkaline material, like household bleach. Wear gloves, goggles and a dust mask. And do not apply wood ash outdoors on a windy day.

Have fun cleaning out the fireplace. You'll need it soon.

Q: I wasn't very good about fertilizing my hydrangeas and fairy princess roses this past summer. Is it too late to fertilize now? What else can I do to prepare them for winter?

A: Wait until spring to fertilize. If you do it now, you may cause soft, new growth that will not make it through the winter.

And don't prune the hydrangeas now. Depending on the variety, hydrangeas have set their buds for next year, and any pruning will reduce their flowering. Prune next year, immediately after blooming. Of course, we have to count on a more mild winter, too, for good blooms. You can, however, remove any completely dead wood at any time.

As for the roses, prune them before leaf buds unfurl next spring.

Winter protection is always a plus, but not a necessity. Burlap wrapping in early winter and mulching after the ground freezes certainly will help. But it's a bit too early for that now.

.Q: My tomatoes were good this year, but there was a ring of white in the outer flesh when you cut them open. What causes that? Is it a deficiency in the soil?

A: This somewhat mysterious.symptom.is not visible to the eye - until you cut or bite into the tomato flesh.

There does seem to be some correlation between a low potassium level in the soil and this disorder. Weather may also play a part in it - it seems to be triggered by extremely high temperatures.during ripening.

It may help if you fertilize the bed this fall with a higher potassium fertilizer. This formula is found in special fertilizers made for tropical plants, or simply a fall fertilizer for general garden use. Check the fertilizer labels for potassium content (look for the K symbol). The last number on the package should be high.

Q: I have a clematis vine at my mailbox facing west. The roots are covered by a cement block. I also mound up mulch another 6 or 7 inches higher to protect the roots from the full sun.

It bloomed beautifully and looked healthy until the intense sun this past summer..Some of the leaves turned brown. I also found a bright yellow spider on the plant. I use a mixture of insecticide - Sevin, RosePride, Orthonex and spraying oil - in all my gardens.

Is there something wrong with it? If I need to move it, when is the best time to do that? And, do you have any suggestions on a similar flowering perennial?

A: First of all, tell me, why would you.want to move it? It sounds like it has the perfect home right where it is.

But if you insist, you can move it this fall. Hurry though, time is getting very short. You can also wait until late winter or early spring, before new growth begins. (If I had a choice, I think I'd do it early next spring.) .

Prepare the new planting hole first.with plenty of well-composted material. Be sure the new place is as good as the old site. Then, dig the plant with as large a root mass as you can handle. Water well, mulch after the ground freezes and baby the vine for at least the first year. Expect some setback in flowering next season.

Clematis are remarkably hardy vines, but our weather has been so unreliable this year.

I don't know much about the yellow spider, but it must be very hardy, with all that you say you are spraying on the garden. Do be careful with mixtures.

This week's dirt: Collect and move your winter gardening supplies indoors. Here are some final chores to consider:

* Clean a few pots - you'll always have a plant that needs repotting next February.

* Buy a couple bags of potting soil.

* On the last mild days, take care of the dirty chores outdoors that you can do best, such as a final bug spraying, plant bathing and trimming.

* Rescue any late-blooming annuals that remain in the garden - they'll be gone after a hard freeze. Pot them up and take them indoors for temporary houseplants: A few dwarf yellow marigolds, some purple or snow-white alyssum, a coleus, or impatiens all make wonderful, but short-lived, plants - and they're free.

Then, get ready to move in for the winter.

nnn

North Shore Gardener by Barbara Barger of Beverly is a regular feature of the Home North section. Reach Barbara by e-mail at nsgardener@comcast.net or write to her c/o Essex County Newspapers, 32 Dunham Road, Beverly, MA 01915.