Original article appeared in Mother Earth by Lolo Houbein.
With temperatures increasing due to global climate change, and long dry summers with more frequent storms, our vegetables have come a long way since their ancestors grew in sheltered valleys in Asia and Europe, where the best agricultural land was once found. In the 21st century, North America’s agricultural land is suffering from wind and water erosion, acidity, salinization, chemical pollution, and the deadening effects of frequent droughts.
Even though our backyards may not have inherited pollution from agricultural practices, they are still subject to climate changes. Once soil repeatedly dries out, microbiotic life and earthworms disappear, and water is not taken up when applied. Therefore, we mulch.
However, once the heat has gone and rains bring cooler conditions, there is no need for thick mulches. Wet straw can become a hotbed for slugs. So let summer mulch rot away, or fork it in and let the soil air a little, unless your region experiences continuous drought with erosive winds. If weeds come up, pull them for compost or liquid manure. Never let them set seed—keep track of weeds. Mulch again in late winter.
Mulches do not have to cost much. Newspaper, cardboard, old clothes, and stones cost nothing. Stones trap moisture when placed around plants, be they lettuce, cabbage, or tree seedlings, but they also attract slugs and snails.
If your soil is rocky, acidic, or unworkable, you may choose to start your 3-foot-square garden from scratch like a no-dig garden, a method developed by gardener Esther Dean.12 Mark a 3-foot square, or build a box with sleepers or planks. Lay down twelve to twenty layers of soaked newspaper with cardboard and old T-shirts as underfelt to prevent persistent weeds breaking through. Make a doorstop sandwich (with thick “slices” of bread) by layering old animal manure, compost, and Lucerne hay. After watering well, make holes in the straw, fill with soil or compost, and plant vegetables. The garden will gradually sink, so keep topping off with CM, hay, or straw. In the first season, plants may not grow fantastically, but the sandwich improves with time.
The most fertile mulches for vegetables are compost, pea straw, or Lucerne hay. The latter is expensive, but gives a new garden a good start. If your climate is severely hot and dry, think in terms of “putting the vegetables to bed.” As soon as plants are above ground, lay sheets of soaked newspaper between them, add wet bags, shirts, or shorts, and top with CM, compost, hay, or straw. After the first watering, watch how long the plants can go without. There is always one plant that is first to look distressed. Keep mulch slightly away from stems and trunks to prevent collar rot.
Black plastic is used for commercial strawberry growing and to suppress weedy lawns. But it cooks the soil and should not stay there long. Weed suppression is its main benefit, and newspaper, cardboard, and telephone books can do that and decay in a timely manner, so that you can mulch and plant on top.
Bracken fern: I wish I still had our forest to pick bunches of bracken. Bracken contains nitrogen, phosphorus, and potassium. Apart from spreading shredded bracken on beds to decay, use ferns as parasols for seedlings.
Cardboard is good for a path between new beds or between straw-filled, no-dig garden plots. If used to suppress lawn or weeds, cover with chipped branches for good looks. Line slatted or wire compost bins with cardboard, pizza boxes, or paper party plates, or use as underfelt in no-dig plots. Only use uncoated cardboard between vegetables.
Clothes can be slow to disintegrate. For that reason, they are best used around the edges of plots for weed suppression or as underfelt for no-dig plots. Half-rotted clothes mulch can still mulch fruit trees.
Grape residue: If you live near a winery, try grape residue from the winemaking process on your plots. Investigate what other free—and safe—residues your neighborhood produces.
Gravel is a marvelous mulch if applied 2 to 3 inches thick. It is mainly used in ornamental gardens around succulents, cacti, and sword-leaved plants, but should you have a supply, try it as a mulch on sturdy vegetables of the cabbage family. Most woody herbs prefer gravelly soil for drainage; just mix gravel with garden soil.
Hay: Legendary tales are told about the effects on a garden of one bale of spoiled hay. Be wary of weed seeds in meadow hay. Great plant food, now sold in handy packs.
Herb stalks: Should you have a flourishing herb plot, do as the Shakers did. They stripped herbs for tea, cooking, and medicine, then spread the stalks as mulch under fruit trees, some acting as a pest repellent. Stalks are best over newly applied compost because they take time to break down as they shade the soil.
Lawn clippings are a quickly decaying mulch, best mixed with coarser materials, such as leaves and broken twigs. Otherwise, apply dried.
Leaves should never be burned, as this causes air pollution and asthma and robs the soil of valuable mulch. First, sweep a layer of leaves under the tree canopy as food, then compost the rest with other organic matter. To make leaf mold for mulch or potting soil, put leaves in a wire cylinder until broken down. Leaves cleared from the gutter in spring are suitably decayed. Sprinkle lime to counteract acidity, and B&B to encourage breakdown.
Mulch blocks are available commercially. Add water to a block to get a wheelbarrow of water-holding mulch to spread around plants.
Newspaper sheets make a weed-suppressing mulch in layers of ten to twelve, but cover this with leaves or straw or you get impervious papier-mâché. Don’t use between small vegetables, which prefer an airier mulch, but use underneath and around the perimeter of plots and under fruit trees.
Oak-leaf mulch or barkrepels slugs.
Olive-leaf residue can be used as a mulch should you live near an olive oil press. Ask whether you may have some to experiment with.
Pine needles are a great mulch around strawberries. Remember, the pine tree needs at least a 4-inch layer itself.
Rock, crushed or as rock dust, contains minerals.
Sawdust must be from untreated wood from your own workshop or your own trees. Use only on paths, in the ornamental garden, and sparingly in the compost, balanced out with lime because many woods are acidic.
Shrub foliage: Prune a few branches. Mow or shred them to make a mulch, or separate leaves from twigs and spread crosswise in layers between plants.
Stones: If you are blessed with a million stones on your land, use them. By planting each plant in an earth saucer surrounded with stones and filling the saucer with CMC, you trap moisture and attract good beetles. To keep slugs and snails away, spread coffee grounds around the stones.
Straw: Keep straw away from seedlings and young plants as there can be some harmful fumes during the breaking-down process.
Sugar cane mulch: This evidently excellent mulch may not be available everywhere, but if it is where you are, look out for the organic variety. Available in small bags.
Twigs: If you are strapped for mulching materials but have wattles (acacia) or shrubs, prune twigs and spread crosswise in layers between plants. This provides an airy mulch that, in time, breaks down into compost.
Weed Mats: Buy only the biodegradable type that lets water through and acts as a mild mulch. For a single 3-foot-square vegetable plot, buy 18 inches of the double width. Depending on the spaces needed between vegetables, cut weed mat into strips of 8, 12, or 15 inches. Place strips in a grid across the plot and plant vegetables in the interstices. Once young plants are well above ground, remove strips or cover with CM and water well. Re-use weed mats.
Woodchips: Some electricity utilities and city councils offer free woodchips after pruning roadside trees. Use for paths in the food garden. Pine wood is beloved by strawberries. At the end of summer, when there is little food about for wildlife, your mulched plots may be dug up at night by unseen creatures—lizards, possums, rats, and early birds—because only there in the moist mulch can they find something to eat. Hence, when planting winter vegetables in autumn, wait to mulch until the days are getting cooler or protect plantings with racks and cages. Mulch again when plants are established and there is plenty of other food for the wildlife.