Garden and Flowers

Plants love mulch because it reduces evaporation of water from the soil surface and reducing weeds which compete with the plants for water and nutrients. If mulch is placed around garden plants, the plants will grow better and be more resistant to diseases. Mulch can also be used on potted plants for the same purpose.

Mulch can be organic or inorganic. Inorganic mulches are rocks, gravel, marble and brick chips. Inorganic mulches can be used in fixed landscape beds that you don’t plan on redigging and replanting. Small gravels migrate easily, working their way down into the soil. Even fairly large rock or brick nuggets can wash or get kicked out of their landscape beds.

Organic mulch does good things for poor soils of almost any type. If the mulch stays on top, the change will happen more slowly but earthworms and microorganisms will slowly break it down and mix it in. However, every time you disturb the bed in any way, such as when you are planting annuals, it happens much faster. Organic mulch adds fertility to sandy soils and helps hold water and nutrients. It loosens and helps drain heavy clay soils and it adds micronutrients that might be missing from even a good garden loam. The organic mulches that are high in lignin which is an organic compound in woody plants, take the longest to break down. Bark has more lignin than wood, so bark mulches last longer than wood mulches. Cypress and pine straw last almost as long as pine bark. The faster the mulch percolates water and the drier it stays, the longer it lasts. Pine-bark nuggets will last a long time. There is a lot of air space between the nuggets, and the microorganisms don’t have enough moisture to break them down.

Mulch cools the soil by either absorbing heat from the sun and not transferring it to the soil (dark organic mulch, such as bark and wood) or reflecting the heat (light mulch, such as rocks or light-colored woods) so that it’s not passed down to the soil below. In most cases that’s good, because overheated roots don’t have to work so hard. In very hot or sunny areas, however, the heat radiated from the mulch can do a number on sensitive plants. o if you’re planning to use bark mulch in a sunny bed, make sure the plants are heat tolerant. This is especially important if the mulched area is large and the plants are young and small. Most inorganic mulches don’t get as hot because they transfer some heat to the soil below.

If you’re buying mulch from large piles that may not have been turned in a while, make sure you give it a sniff test first. Good mulch has a clean smell like fresh-cut wood or soil. The odor of vinegar, ammonia, rotten eggs or silage means that the mulch has gone sour–a toxic condition that results from too much moisture and too little oxygen. Sour mulch can seriously damage and even kill plants within 24 hours after application.

You can easily suffocate a plant by mulching too deeply. The same goes for laying any impermeable cover such as plastic or several layers of cardboard that doesn’t allow the soil to breathe. This will cause root problems. The less porous and more compactable the mulch, the thinner you spread it. For very finely shredded hardwood, no more than two to three inches deep; coarse nuggets, three to five inches; loose straw, up to six inches deep for wintertime protection of sensitive plants. Top off aging or discolored mulch with a minimum of new material.

Don’t give wood borers and other insects easy access to your trees, shrubs and herbaceous plants,leave a space of eight inches between mulch and tree trunks or tender stems. Be sure to keep wood products away from your home’s foundations.