November 2010 Newsletter©
What should I do in the fall?
This month I thought we would talk about some of the fall garden chores and why we do them. We’ve touched on much of this information before, but for the newcomers, and as a recap for our longtime customers, I think it is good to cover it again.
Why should I mulch?
There are many benefits to mulching. It helps control weeds, retain moisture, moderate soil temperature swings and it looks good. It can also cause problems…let’s look at why.
In the wild, nature adds a layer of leaves each year. It doesn’t matter whether it’s a grassland, conifer forest or hardwood forest, each year you get a thin layer of leaves laid down as mulch. It may appear to be quite thick, 6” to 8” or more, but most of the depth is air space between the leaves. The ground temperature is still fairly warm in late fall, so root growth is continuing. The air space between the leaves allows water and air to move freely and it helps insulate the ground from rapid air temperature swings. Step on them and they’ll compress to a fraction of an inch, so even though it may look really deep, there really isn’t that much organic matter being added to the surface.
When you mulch your flower beds with bark, you’re laying down 2 or more inches of wood. Step on it and it is still 2 inches deep. That doesn’t happen in nature. The first year or two, the results are the same as in nature. The mulch is coarse, air and water move through it well, weed seed can’t get to the soil to germinate, the soil moisture is retained well and the soil is insulated against rapid temperature changes, all is well in the world.
Each year, the leaves decompose and eventually become part of the top soil but it takes about 100 years to form an inch of topsoil. Remember… a years worth of leaves is very thin. Your bark mulch is decomposing also. You’ve added hundreds of times more organic matter with bark mulch as nature adds with leaves. The bark decomposes into a layer of very fine powdered bark much faster than it can be turned into top soil. This layer gets deeper each year and with each application of mulch. Many people think their mulch has washed away. It hasn’t, it’s just turned to powder.
This powder doesn’t hold water or nutrients well. Many people plant in this thinking it is rich soil. It’s not and plants perform poorly when planted in it alone. The deeper this layer of powder becomes, the less air moves to the soil surface and the soil surface stays wetter, longer. Some plants will tolerate this, but many of our favorite plants will not.
Evergreen azaleas are native to hilly and mountainous areas of Southeast Asia. They get substantial water but they have excellent drainage and the movement of water down the hill prevents soil and leaves from accumulating on the roots. We live at the bottom of the hill. Anything on the root zone stays there. Slow the air movement to an azalea and nothing good happens; Phytophora root rot, chlorotic and dwarfed foliage, azalea dieback. Japanese hollies are more prone to black root rot, perennials to crown rot and annuals to root and stem diseases. The list goes on and on.
It may sound like I’m trying to talk you out of mulching, but I’m not. However, look at your soil. If you see this layer of powder, rake everything out back down to clay and then re-apply a 2” layer of fresh coarse mulch. You may not need to rake it out every time you mulch, just don’t let the layer of bark powder get very deep.
You can save the stuff you rake out and add it to the compost pile or incorporate a little into the clay when you’re planting; it’s just not much good by itself.
Most roots are at, or near, the surface in our clay soil because that’s where they need to be. Clay is slow to dry and holds water well, so during our rainy times, many plants need access to air. Don’t let them get too deep!
Another thing to remember about mulch is this…it’s best to not let it touch the stem or trunk of any desirable plant especially during the growing season. Even if you use leaves, don’t let them accumulate in the crotch or around the base of multi-stemmed plants. Mulch will keep the stems wet and this is an open invitation to disease and insect problems.
For information on types of mulch, read the November 2006 Dan West Newsletter.
Why should I use a dormant oil spray?
We probably should stop calling it a dormant oil spray. For years we recommended it for broadleaf evergreens when the temperature was between 32° and 90°, and for dormant deciduous plants. However, that has changed. There are no temperature restrictions anymore and many of the oil sprays on the market have vegetable labels for use up to the day of harvest. There are still a few plants you want to use it with caution on, so check the label, but as long as the plant is not drought stressed, it can be used on many, many plants.
Now back to the reason we use it in the fall. Oil sprays cover and smother any over-wintering insects or insect eggs on the plant. It also helps seal the plant against water loss. Most of the borderline hardy plants we grow here, suffer winter damage from the drying wind. The oil spray helps a plant retain its moisture and it is much less likely to be damaged if it has been sprayed with an oil spray.
What should I do to my houseplants to bring them in?
The first thing to do is spray the plant with an insecticide if you see any insects. Look close for scale insects and mealybugs. The oil spray above makes a great houseplant spray for most plants (check the label). It kills the insects, seals the foliage to help prevent water loss when you move it into a warm dry house and it shines the foliage.
Then, set them in the sink or tub and run water up to the top of the pot. Let them sit for 20 minutes or so and this will flush out or drown many soil insects. Then I’d treat them with systemic houseplant granules containing imidacloprid. This will kill any fungus gnat larvae in the soil and because it is systemic and is absorbed by the plant, it will give you several months control for insects.
Try to place your houseplants in the same type of light they were in. If they were in full sun, try to put them in a southern window. If they were in the shade, an eastern or western window with shears should be fine. If the spot you want them is low natural light, then try to supplement the light by placing a lamp nearby. If you are keeping large plants, like sago palms, in the garage for winter, set them outside whenever we are not expecting a frost or freeze and they will still look great next spring.
Don’t panic if you start to get internal yellow leaves and some leaf drop. If you lower the light much, it can’t support all that foliage, so it sheds some off. It’s just trying to correct what you did to it.
Why should I use a pre-emerge herbicide?
So you don’t have to pull or spray as many weeds next spring. Pre-emerge herbicides form a chemical barrier at the soil surface that kills seedlings as they germinate. Many of the weeds you’ll see next spring (annual bluegrass, chickweed, henbit, deadnettle, etc.) come up in the winter. Some are already up, but if you haven’t applied a pre-emerge yet, go ahead and start. You’ll still stop some weeds. It has been so dry, many weeds haven’t germinated yet. If you apply Dimension every 90 to 120 days to your lawn and flower beds, you’ll control most of your weeds. Of course, don’t apply it if you plan to sow any seed in the next three months on in areas where you flowers return from seed each year.
Should I plant a cover crop on my vegetable garden?
A cover crop or “green manure” is one of the best things you can do for your garden. The roots help break up the soil and the foliage adds nutrients and organic matter back when you till in under in the spring. Two good choices are rape (the plant canola oil comes from) or annual ryegrass. And yes, we have the seed for both!
I want to invite you to drop by the nursery if you like camellias. Many of the fall blooming varieties are in full bloom.
I also want to mention a few newcomers:
Two University of Tennessee flowering dogwood varieties…
Karen’s Appalachian Blush Dogwood – Flower petals are white, tipped in pink. Heavy bloomer and shows good resistance to powdery mildew.
Kay’s Appalachian Mist Dogwood – A white flowered selection that produces huge numbers of flowers and is very resistant to powdery mildew.
Also two Kousa dogwood varieties… (Kousa dogwoods bloom after the leaves emerge)
Galilean - A rapid growing variety with large white flowers in May/June followed by bright red fruit and excellent red fall color.
Samaritan – White flowers in May/June, green leaves are edged in white, excellent burgundy fall color, very vigorous growth.
Don’t miss our Christmas Open House – November 6th from 10 to 4 and November 7th from 11 to 4.
This was the September contest. We didn’t get a correct answer on this one. It is bowtie vine, Dalechampia dioscoreifolia. It’s an annual here and we grow it for sale every year. It’s a very rapid growing vine and blooms profusely in full sun with 3” bowtie like purple flowers.
This time, instead of a plant identification question, the contest is a math problem. (I hear the moans!)
Let’s assume you have ½ acre of land. If you get 1” of rain on it, how many gallons of water would that be?
The contest ends on November 15th. Drop by either store to enter or you can email your entry to
questions@danwestonline.com. One winner, selected from all correct entries, will receive a
$25 Dan West Gift Certificate.
Thanks for shopping with us at Dan West.