The best time-saving measure a gardener can take is applying mulch. This goes for every garden site, from vegetable garden to flower bed. Mulched gardens are healthier, more weed free, and more drought-resistant then unmulched gardens, so you'll spend less time watering, weeding, and fighting pest problems.
There are two basic kinds of mulch: organic and inorganic. Organic mulches include formerly living material such as chopped leaves, straw, grass clippings, compost, wood chips, shredded bark, sawdust, pine needles, and even paper. Inorganic mulches include gravel, stones, black plastic, and geotextiles (landscape fabrics).
Both types discourage weeds, but organic mulches also improve the soil as they decompose. Inorganic mulches don't break down and enrich the soil, but under certain circumstances they're the mulch of choice. For example, black plastic warms the soil and radiates heat during the night, keeping heat-loving vegetables such as eggplant and tomatoes cozy and vigorous.
Using Organic Mulches
There are two cardinal rules for using organic mulches to combat weeds. First, be sure to lay the mulch down on soil that is already weeded, and second, lay down a thick enough layer to discourage new weeds from coming up through it. It can take a 4- to 6-inch layer of mulch to completely discourage weeds, although a 2- to 3-inch layer is usually enough in shady spots where weeds aren't as troublesome as they are in full sun.
Wood chips and bark mulch: You can purchase bags of decorative wood chips or shredded bark from a local garden center to mulch your flower garden and shrub borders. A more inexpensive source of wood chips might be your tree-care company or the utility company. They may be willing to sell you a trunkload of chips at a nominal price. Many community yard waste collection sites offer chipped yard debris or composted grass clippings and fall leaves to residents for free (or for a small fee).
Shredded leaves: If you have trees on your property, shredding the fallen leaves creates a nutrient-rich mulch for free. You can use a leaf-shredding machine, but you don't really need a special machine to shred leaves—a lawn mower with a bagger will collect leaves and cut them into the perfect size for mulching.
You can spread a wood chip or shredded leaf mulch anywhere on your property, but it looks especially attractive in flower beds and shrub borders. Of course, it's right at home in a woodland or shade garden. Wood chips aren't a great idea for vegetable and annual flower beds, though, since you'll be digging these beds every year and the chips will get in the way. They do serve well as a mulch for garden pathways, though.
Grass clippings: Grass clippings are another readily available mulch, although it's a good idea to return at least some of your grass clippings directly to the lawn as a natural fertilizer (see the Lawns entry). It's fine to collect grass clippings occasionally to use as mulch, and the nitrogen-rich clippings are an especially good choice for mulching vegetable gardens. Your vegetables will thank you for the nitrogen boost!
Compost: If you have enough compost, it's fine to use it as a mulch. It will definitely enrich your soil and make your plants happy, but keep in mind that when any kind of mulch is dry, it's not a hospitable place for plant roots. So you may want to reserve your compost to spread as a thin layer around plants and top it with another mulch, such as chopped leaves. That way the compost will stay moist and biologically active, which will provide maximum benefit for your plants.
Pine needles: Pine needles are a trim-looking mulch for garden beds. They allow water to pass through easily and they break down slowly. Despite what you may have heard, using pine-needle mulch will not make your soil significantly more acid.
Straw and hay: Another great mulch for the vegetable garden is straw, salt hay, or weed-free hay. It looks good and has most of the benefits of the other mulches: retaining soil moisture, keeping down weeds, and adding organic matter to the soil when it breaks down. But be sure the hay you use is weed and seed free, or you'll just be making trouble for your garden. And don't pull hay or straw up to the stems of vegetables or the trunks of fruit trees or you'll be inviting slug and rodent damage.