Other than adding to the beauty of your landscape by providing interesting textures and colors, mulching improves the quality of your plants and mimics natural forest environments. Mulching not only keeps plants healthier and improves soil structure; it drastically reduces the need for weeding by preventing germination. It also helps maintain more even moisture levels.
By preventing the top layer of soil from drying out, mulching enables water to move more easily and to be absorbed by the soil. Evaporation of water from the soil can be reduced by as much as 25% when you mulch with a 2”–4” layer (after it settles), meaning less watering is needed.
Mulch also keeps the soil cooler in summer and warmer in the winter. Soil erosion and water runoff are halted when you mulch. Microorganisms in the soil that help promote root growth and earthworms thrive as the mulch begins to decay.
Mulching also helps reduce soil compaction from raindrops and sprinklers and the splashing of fungi and soil borne diseases onto the plants. When you mulch around your plants, you develop a well defined area that provides a barrier from damages caused by mowing and weed eating.
This physical boundary is also aesthetically pleasing and reduces the need for landscape maintenance. Be cautious about use of mulch in very humid areas.
The mulch can hold too much moisture that creates an environment for slugs and snails. It can also cause stems that come into contact with the mulch to rot
Application: It's best to mulch when you plant your new plant. The best time to mulch established plants is in late spring when the soil has warmed up. If it’s applied earlier, it can delay the plant coming out of dormancy and delay growth. Late fall is good, too, after the ground has frozen. Mulch will act as an insulator for the tender roots. Sandy soil will need more mulch (4”-5”) to keep it from drying out as quickly.
If your mulch is coarse, you will also need a thicker application than with finer mulch materials. Low areas that collect water or have a lot of clay won’t benefit much from mulching. The area around the plant should be free of grass and weeds before adding mulch. Mulch will not kill these, but will keep the seeds of most from germinating. If planting in beds, mulch the whole bed. If mulching around trees or shrubs, plan to mulch 3- 6 feet from the center of the plant.
When a plant doesn’t have to compete for moisture or nutrients with weeds, it can grow faster and healthier. It’s advisable to move the mulch an inch or two away from the bark to prevent rot. Also, keep the mulch about a foot away from buildings. Be sure the mulch you use is free of weeds, non-clumping, and easy to apply.
Some of the best materials include compost, pine straw, and pine bark. Pine straw stays in place well, but breaks down quickly. Pine bark nuggets don’t break down as quickly, but can easily float away with watering or rain. Compost can be purchased or created in your backyard from leaves, grass clippings and food scraps.
Researching composting methods will be very beneficial rather than just using piles of rotted materials. As organic materials decompose over time, they release small amounts of nutrients into the soil. This helps plants thrive by increasing root production and keeping soil structure loose and nutrient rich. These materials need to be replaced to maintain the 2”-4” depth of mulch. Usually this means adding an inch to previously mulched areas. Pine straw needs to be replaced annually, while pine bark, which should contain less than 10% wood fiber, may not need reapplication for 2-3 years.
Compost needs to be replaced 2-3 times per year. However, as plants grow and fill in areas, less mulch will be needed. Leaves can be used as mulch if they are coarsely shredded, using a lawn mower or shredder. Whole leaves have a tendency to blow away and to pack so tightly that they don’t allow water to penetrate the soil.
Possible Problems: Do not over mulch or mound into volcanoes. More is NOT better. If the mulch is too thick it can suffocate the plant. Water will not be able to move easily through it and this will force roots to grow closer to the surface to seek moisture. Organic mulch can be a breeding ground for slugs, snails and some insects. Applying wood ash, Celatom (celite), or slug and snail bait should remedy this problem.
Mulch that is too compacted can sour (smells like vinegar, silage, sulfur or ammonia) and can quickly damage tender young plants. Mulch needs air and water to decompose properly. Without the ability to breathe, anaerobic conditions occur and the microbes produce toxic substances (acids and alcohols) that can kill plants. Indications of this problem, besides the odor are scorching, dropping or yellowing of the leaves, and possibly death of a plant. If this problem exists in your beds, turn your mulch one or two times each month, or more if it is very wet. Be sure to check that the depth of the mulch does not exceed 3” (settled). This should remedy the problem within a day, but allow up to three days to be safe.