The fourth week of September celebrates cool nights and the end of warm afternoon sunshine — perfect weather for transplanting, digging and dividing perennials and fertilizing the lawn with a slow-release, fall and winter lawn food.
If you only fertilize your grass once a year, make it an autumn feeding. A lawn fertilized in the fall with an organic or slow release fertilizer will have an advantage over the weeds in the spring. This is because the winter rains can move the nitrogen down into the grass roots where it will be available immediately in February when the lawn wakes up from winter dormancy. Here’s the secret to more grass and less weeds: a lawn that has nitrogen at root level in early spring can outgrow and overcome the shallow rooted weeds. A thick lawn is your best weed defense. You still have time to aerate, add an inch of topsoil and overseed your old lawn before winter sets in. Tackle these fall field goals now and you’ll be scoring great yardage all year long.
Q. When should I apply lime to my lawn? I know my soil is acid because I have a lot of moss in the lawn. I do have hard-packed clay soil, and I have read that lime will help break up clay soil. True? — S.T., Sumner
First, congratulations on knowing the benefits of lime. Adding lime is the least expensive way to improve your lawn. You can add lime to your lawn any time of the year, but do not lime on the same day you add fertilizer. You could cause a chemical reaction that binds up some of the nutrients in the fertilizer. Instead, fertilize first, then wait a few days until rain washes the fertilizer down into the soil and then apply the lime. It’s true that if your soil is heavy, lime helps to break up the clay and allows air and moisture to penetrate.
Our soils in Western Washington are naturally very acidic due to the rain. This low pH or acidity binds up nutrients in the soil. Lime is not a fertilizer, but it helps to unlock phosphorous and nitrogen in our wet soils so that lawns can green up quickly. You can buy lime in a quick acting or pelleted form or as powdered limestone and it is sometimes sold under the name “Soil Sweet.” Follow the dosage amount on the package, but in general you will need fifty pounds of ground limestone to 1,000 square feet of lawn to raise the pH a full point. A simple soil test sold at garden centers can tell you the pH of your soil, but mossy, damp soils in our area are almost always very acidic. Lime is the cheap and easy answer to a better lawn.
Q. I planted a gorgeous “Black Lace” Sambucus or chocolate elderberry a few years ago and love the dark chocolate foliage, pink spring flowers and autumn berries. My problem is this shrub has grown too big and is now a tree! I must prune it. Would fall be a good time to cut it back? — R.S., Tacoma
Patience and some persistence will keep your “Black Lace” Sambucus under control. Wait until early spring, in the month of March to sharpen your shears and cut your sambucus down to size. A severe pruning always stimulates growth and now is not the season to encourage tender new leaves. Another reason to wait is so that the birds can enjoy those berries all winter. You can cut back all of the new growth to one-inch stumps or you can saw down the trunk and start all over. This is one tough shrub so don’t be afraid to be severe in the spring.
Elderberry is native to our climate, has edible berries and does great with our wet winters. I’ve found elderberry even survives and blooms a little in a deeply shaded bed where the dark, chocolate leaves make a lovely background for variegated shrubs. A colorful couple to share a shady bed with no drinking problems would be “Black Lace” Elderberry getting cozy with “Mr. Goldstrike” Aucuba. The gold-splattered leaves of aucuba have a broad and bold texture that makes a pleasing contrast with the fine texture of the chocolate elderberry.
Q. I have a compost pile and am not sure what to do with it. I’ve been adding grass clippings and garden waste for a few years and under the newer layer of clippings I do see dark soil, so I think I have compost. When do I spread this onto the garden beds? In the spring or in the fall? How deep do I apply the compost and must I dig it into the vegetable bed? — C., Email
What a wonderful gift you have for your garden. You can add compost to your vegetable and flower beds this month and let the winter rains help mix in the organic matter. If you have small weeds, fork the compost right on top of them now in a layer up to six inches deep. The heavy compost will smother those weeds and then you can work it into the soil in the spring. Use a very thin layer of compost – less than one inch deep near the stems or crowns of shrubs and perennials if you apply it in the fall. Compost in our climate can hold so much moisture over the winter that it can encourage crown rot. Don’t worry if the newer grass clippings and garden debris on top of your compost pile are not yet well-rotted. You can add this half-done compost to an empty bed or vegetable plot and not dig it into the soil until spring. Winter is the season when all things rot and in a few months that chunky organic matter will be dark and soft, ready to work into the topsoil.Marianne Binetti has a degree in horticulture from Washington State University and is the author of several books. For gardening questions, write to her at P.O. Box 872, Enumclaw, WA 98022. Send a self-addressed stamped envelope for a personal reply. She also can be reached at her website, binettigarden.com.