Mulching Isn’t Just an Activity for Summertime
Have you ever seen ground left uncovered by nature? OK, maybe sand dunes, but even the desert floor is generally covered by a mulch of gravely stones. Peer under our chaparral and you’ll find several inches of duff--dead leaves and twigs that are slowly decomposing. Ditto under oaks.
Walk through a woodland: The ground is almost bouncy underfoot because of leaf litter decaying on the forest floor.
Even granite cracks on mountain crags collect decaying vegetation. It becomes sustenance for the pioneering “rock plants,” which, despite the name, cannot live on a diet of mineral flakes.
Everywhere one goes, nature has carefully tucked in her plants under a blanket of mulch.
Gardeners should follow suit, and although the praises of mulch are most often sung in summer, winter may actually be the better time to cover all that bare earth in the garden.
It’s true that in summer, a thick mulch keeps moisture in the soil, cools it somewhat and prevents weeds, but in winter, even a thin mulch keeps the pounding rain from pulverizing the soil.
After a rain, observe what your soil looks like. Is it still soft and crumbly, as it was when you laboriously prepared it with amendments and turnings, or does it look like a silty eroded creek bottom?
Also note how much of the soil has splashed up onto the foliage of plants. Not only is this untidy, but it gives you some idea of how much churning the rain is causing.
Wait a few days for this silty slurry to dry and try to cultivate the soil. You’ll probably find that it has caked hard. You can break it up (and you should), but it will fracture into miniature tectonic plates. Only after a good deal of effort will it become moist and crumbly again.
If you do not break up this silty layer, it will crack on its own as it dries, and the next rain will bounce off this armor plate, sitting in puddles or heading for the storm drain. Silty damaged soils flood; mulched soils rarely do.
Oxygen to Roots
Rain should be able to enter the upper soil easily and pass through quickly, pulling air behind it as it passes, providing roots with oxygen. Roots (and soil bacteria) need oxygen, just as the tops of the plants do.
Spreading a rain-deflecting mulch on the soil will greatly help. The power of a free-falling raindrop will be dissipated by the mulch, so the structure of the soil underneath is not disturbed, and the mulch will help hold the water momentarily while it soaks in.
This would seem to be especially important this year because there are so many heavy downpours contained in this season’s storms.
Try this yourself right now. Lightly cultivate two patches of earth and then cover one with fallen leaves and leave the other bare. See which looks best after a downpour.
The trick will be finding something to mulch with. Nurseries and packagers have been slow to provide good mulches.
Go out this weekend and try to buy a mulch and you’ll find two choices--chunky bark and gravel--neither of which is particularly good for the garden, because both decay rather slowly.
Since these materials decay so slowly or not at all, they don’t meld with the soil, or add anything to it. They don’t make a moist organic layer at the soil surface but just sit on top in a rather awkward and unnatural fashion. You might as well cover your soil with Coke cans.
In my book, chunks of bark have no use in the garden, and gravel is best for heavy-duty paths or as a mulch around sensitive plants that need to dry out quickly, such as cactus.
There is one nursery-bought alternative, if you can find it, and that’s shredded bark. At a recent horticultural trade show, there were many different kinds available to retailers, but I have seen few of them at nurseries.
The individual pieces of shredded bark are flat, so it packs down nicely, and they are all different sizes, from tiny to large. Not only does it look more natural, but some of the smaller pieces can actually decompose. Still, it makes a better path than a mulch.
What’s really needed at nurseries is something similar to what comes out of a home compost pile, before it has completely decomposed. Call it half-baked compost.
This adds nutrients and tilth to the soil, yet the coarser nature of the half-baked compost keeps it from packing down too tightly, or from floating away. As it continues to decay, it adds good stuff to soils.
Fallen leaves also make a good mulch, if you can gather them up before a hired gardener blows or carts them away (that should be a criminal offense).
At this time of year you may find an overlooked supply of leaves in the sideyard or back behind some trees. By now, they should be good and wet and partially decomposed.
One of my trees is still dropping leaves (a Tabebuia waits until February to go briefly dormant), so this weekend I was raking up leaves and carefully putting them around plants, in this case seedlings that have finally grown big enough to be mulched.
Keeping Weeds Down
You can’t sow seeds on mulched ground--which is why they keep down weeds--so you need to wait until the seedlings are tall enough. Everything else should be mulched at all times.
Some people simply haven’t thought of mulching in winter, or of renewing a mulch because the best kinds do decompose, but what a difference it makes.
Others find mulches messy, believing bare ground better, but they really need to learn the difference between house and garden. Clean carpets are great; a swept garden is not, if you want happy, healthy plants. It’s gotten to the point in my garden that I find bare earth unbearable and, like a spider spotting a hole in its web, scuttle off to quickly cover the breach before the next rain.
(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)
Garden Events
Walks, Talks, Shows and Special Sales
Saturday: Seminar on thrifty home irrigation by Rick Fisher, 9 a.m.-noon, at the Theodore Payne Foundation, 10459 Tuxford St., Sun Valley; (818) 768-1802. $30.
Saturday: Children’s workshop on bonsai, 9 a.m.-noon, Huntington Botanical Gardens, 1151 Oxford Road, San Marino; (626) 405-2141. $10 advance registration includes plant and free admission for one accompanying adult.
Saturday: Lecture and demonstration on topiary by Patricia Hammer, 1-3 p.m., Quail Botanical Gardens, 230 Quail Gardens Drive, Encinitas; (760) 436-3036. $12; reservation required.
Saturday: Lecture on good bugs in the garden by Lili Singer, 10 a.m.-noon, Rancho Los Cerritos, 4600 Virginia Road, Long Beach; (562) 570-1755. $3.
Saturday: Program on tree pruning by John Bishop, 9:30 a.m., Sherman Gardens, 2647 East Coast Highway, Corona del Mar; (714) 673-2261. Free.
Saturday: Lecture on history, botany and culinary use of lemons by Southern California Culinary Arts group, 12:30-2:30 p.m., Huntington Botanical Gardens, 1151 Oxford Road, San Marino; (626) 405-2141. $50; registration required.
Feb. 22: Workshop on bonsai by Gardena Bonsai Club, 9 a.m.-noon, Earl Burns Miller Japanese Garden, Earl Warren Drive (across from parking lot D), Cal State Long Beach. $35, includes plant, pot and workbook. Register by calling (562) 985-8885.
Send garden announcements to Garden Events, Los Angeles Times, Times Mirror Square, Los Angeles, CA 90053 at least three weeks before the event date.
