I used to be a total mulcher, covered my whole veggie garden. I’ve adjusted my coastal SoCal *mulch thinking to match the plant! Same goes for composting in place. That’s a good idea for some areas of your garden, other areas not at all!
If you are coastal SoCal, in the marine layer zone, your mulch, or composting in place, may be slowing things down a lot more than you realize. The best melons I’ve ever seen grown at cool & coastal Pilgrim Terrace Community Garden were on bare hot dry soil in a plot that had a lower soil level than most of the other plots. The perimeter boards diverted any wind right over the top of the area, the soil got hot! It was like an oven! So, let it be bare! No mulch under melons, your winter squash, pumpkins except under the fruits to keep them off the ground, clean, up from insect predators.
Put up a low wind barrier – straw bales, a perimeter of densely foliated plants, a big downed log, be creative. Let your peppers and jicama get hot! Eggplant is Mediterranean, maybe coastal, because they like a little humidity, interplant them closely with other plants, but still they are heat lovers! Okra is full sun Southern hot!
Tomatoes need dryer soil to avoid the verticillium and fusarium wilt fungi if your soil has it. Plant them in a basin that keeps the water out! Make the basin on top of a mound with the basin bottom level above the surrounding soil level. Let ‘em dry nearby; water a foot or more away from the central stem. Let that tap-root do its job, get the water below the fungi, wilt/blight zone, the top 6 to 8 inches. Drier soil is not comfy for slugs.
Get cucumbers up on a trellis, then you won’t need mulch to keep the cukes clean and bug free, but rather because they have short roots. Cukes are susceptible to fungi wilts/blight too, so keep the leaves from touching bare ground. As soon as they are big enough, clip off lower leaves that might touch the ground when weighted with water in case they get wet. They are a fuzzy plant, so better to water at the root, not on the leaves anyway. Plant heat tolerant lettuces at their feet to act as living mulch. They both like plenty of water to keep them growing fast and sweet, so they are great companions. In that case you will need to use a little Sluggo or its equivalent if you feel comfortable to use it.
WATER Clearly, no mulch, more heat, equals more water needed. In drought areas, plant in basins below the surrounding soil level. Use your long low flow water wand to water only in the basin at the roots of your plant. Fuzzy leaved plants, tomatoes, cucumber and eggplant, prefer not being watered on their leaves anyway. Since there is no raised mound, there is no maintenance needed for berms surrounding a basin though there is natural settling so you do need to clear the basin occasionally. If you are in a wet area, make those mounds with the bottoms of basins above the surrounding soil level for good drainage and check the berms from time to time to be sure they are holding up. These are variations on age old Waffle Gardening.
LIVING MULCH Closely planted beets, carrots, garden purslane, radish, strawberries, turnips act as living mulch to themselves. The dense canopy their leaves make lets little light in, keeps things moist. If you cage or trellis your beans, most of the plant is up getting air circulation, keeping them dryer, more mildew free, if you don’t plant too densely. They, cucumbers and strawberries, also have short feet that need to stay moist, so do mulch them – your beans and cukes with clean chop and drop or purchased mulch. Chard likes moist and cooler, so mulch. Zucchini, doesn’t care. They are a huge leaved plant, greedy sun lovers, that are self mulching. But, you can do what some do. Feed their vine up through the largest tomato cages, stake them well, that plant is heavy. Cut off the lower leaves and plant a family of lettuces, carrots, onions, salad bowl fixin’s or basil on the sunny side underneath! If you are in a hot drought zone, plant them in the filtered shade underneath. All of them like plenty of water, so everyone is happy.
If you are going to mulch, do it justice. Besides wanting to cool your soil, keep moisture in, prevent erosion, keep your crop off the soil and away from bugs, and in the long-term, feed your soil, mulching is also to prevent light germinating seeds from sprouting. Put on 4 to 6 inches minimum. Less than that may be pretty, but simply make great habitat for those little grass and weed seeds! Mulch makes moist soil, where a rich multitude of soil organisms can thrive, including great fat vigorous earthworms! You see them, you know your soil is well aerated, doing great!
If you live in a cold climate, cold, cold winters, mulch can protect your soil and keep it warm in winters. In SoCal, pull mulch away in ‘winter’ to let the sun warm the soil, remove overwintering pest habitat, let soil dry so fungi die. Pile it near your compost area and use it in compost layers if it is pest and disease free.
Mulching is double good on hillsides. Make your rock lined water-slowing ‘S’ terrace walkways snaking along down the hillside. Cover your berms well and deeply to prevent erosion and to hold moisture when there are drying winds. Use a mulch that won’t blow away or garden staple down some plastic. Plant fruit trees, your veggies on the uphill side of your berms.
Mulch with an organic degradable mulch that feeds your soil too! Chop and drop disease and pest free plants to compost in place, spread dry leaves. Spread very well-aged manures. When you water, it’s like compost or manure tea to the ground underneath. Lay out some seed free straw – some feed stores will let you sweep it up for free! If you don’t like the look of that, cover it with some pretty purchased undyed mulch you like. Use redwood fiber only in areas you want to be slightly acidic, like for strawberries.
COMPOSTING IN PLACE Build soil right where you need it. Where you do put mulch, tuck kitchen waste out of sight under it, where you will plant next. Sprinkle with a little soil if you have some to spare, that inoculates your pile with soil organisms; pour on some compost tea to add some more! Throw on some red wriggler surface feeder worms. Grow yarrow or Russian comfrey (Syphytum x uplandicum) near your compost area so you can conveniently add a few sprigs to your pile to speed decomposition. It will compost quickly, no smells, feeding your soil excellently! If you keep doing it in one place, a nice raised bed will be built there with little effort!
You don’t have to wait to plant! Pull back a planting space, add compost you have on hand or purchased compost, maybe mix in a little aged manure mix, worm castings, specific amendments to the kind of plant you will be planting. Sprinkle some mycorrhizal fungi on your transplant’s roots, and plant! Yes!
A caution: The debris pile of composting in place may be habitat for overwintering insect pests, so put it safely away from plants that have had or might suffer infestations. To break a pest’s growing cycle, put no piles at all where there have been pests before.
In SoCal and southern states, when temps are 85 degrees or above for 3 to 4 days in a row, check for BAGRADA BUGS on any Brassica plants you have – broccoli, kale, collards, cauliflower, Brussels sprouts, nor Mizuna, mustard, radish, arugula or turnips. If Bagradas are there, some gardeners immediately remove all Brassicas and all the surrounding mulch to remove Bagrada habitat, stop them laying eggs in the soil. Those gardeners then wait for cool weather again before planting any more Brassicas.
In the fall most SoCal gardeners remove tired mulch to remove habitat for overwintering pests or diseases, to let the soil warm up on short sunny ‘winter’ days. Some toss it completely away, dig it into landscaped areas to feed the soil. If clean they compost it. If you are in a snow zone, you would keep it on to keep the soil as warm as possible, cover and protect plants from freezing.
So, you see, there are times for mulch and times not for mulch. Using less saves money, saves work.
Mulch is magic when done right!
*Mulch is when you can see distinct pieces of the original materials. Finished compost is when there are no distinct pieces left, the material is black and fluffy and smells good.
Updated from June 11, 2011 post