The fourth week of August is time to answer the latest garden questions sent in by local gardeners:

Q.How can I stop lichen from growing on the bark of my birch trees? I do not like the look even though I know the lichen does not harm the tree. P.K.

A. If you do not like the lichen, you can scrub it off with a stiff brush and if you want to get really persnickety you can be like the garden owner in England that uses a bit of bleach in a bucket of water to scrub the birch trees each spring so the bark stays white.

The warning here is the dripping bleach water can kill plants beneath the tree and add an unintentional fashion statement of bleach spots to your clothing. An old gardening tip from the past century recommended using horsetail weeds to scrub the bark of trees. The sand in the horsetail rubs off the lichen and the juice stops it from coming back.

Or you can just learn to like the lichen.

Q. How do I keep my tomatoes from getting rotten before they are ready to harvest? R. Email

A. Keep your tomato plants dry and they will not be able to contract the late blight disease that is spreading in area gardens. Some gardeners build a cage of plastic around each plant making sure there is a way to vent the top on hot days.

A more practical approach is to plant tomatoes under the eaves of the house on the hot west or south side. Once you see dark spots forming on the stems and leaves it is too late to stop late blight. My sympathies.

Q.We bought a small eggplant from a garden center and it has done well in a container on our patio. The purple fruit are small but very beautiful. The question is how does one know when an eggplant is ripe? I assume we can eat an ornamental eggplant right? N.L. Buckley

A. Yes, the tiny ornamental eggplants are edible. You can slice, stir fry or bake eggplant no matter what size the fruit at harvest time.

But you must harvest the eggplant while it is still young and the skin glossy. If you wait too long the eggplant will form seeds inside and this can make the flesh bitter and spongy.

There are many different varieties of eggplant and the weather determines how long it takes to ripen on the plant. Start harvesting once the skin is dark and the fruit filled out.

Q.Is it better to water the lawn in the evening or in the morning? Anon

A. Early morning watering is best in Western Washington because watering at night can encourage the fungus among us. Just remember that too much water given to a lawn can cause problems so aim to apply just one inch of water a week.