Mulching is one of the best things we can do for our landscape plants for a lot of reasons. Most of us use mulch, simply because it makes our plants looks better. But improving the landscape’s appearance is only one of many benefits of mulching.
My information on mulching was prepared by Emeritus Extension Urban Horticulture Specialist Dr. Robert Black of the University of Florida, Institute of Food and Agricultural Sciences.
It’s hard to decide which of the benefits of mulching is most important. For one thing, mulching makes it harder for weeds to grow in shrubbery and flowers beds. Also, mulch acts as an insulating blanket over plant roots, keeping them cool in hot weather and warm in cold weather.
Another advantage is that by slowing evaporation, mulch helps to conserve moisture in the soil. It reduces the crusting that can occur at the soil surface when the soil dries out. This is important because water from rain or irrigation will then be able to move into the soil instead of running off and causing erosion.
As organic mulches decompose on the soil surface, organic matter works its way down into the soil. This improves soil texture and may even increase soil fertility by a small amount. And of course, we all know that mulching just makes the landscape look better.
We use two types of mulching materials, organic mulches and inert mulches. Organic mulches include compost, bark, leaves, grass clippings, straw, wood chips, sawdust and similar materials. Inert mulches are things like gravel, pebbles polyethylene or plastic film and even aluminum foil.
Applying mulch is a simple matter. Just spread a two-to-four inch thick layer of the material around the base of newly planted landscape ornamentals. Be sure not to get the mulch so deep that it’s up around the trunks or lower branches of your plants. Then, add more mulch as needed during the year. The spring is usually the best time to add mulch around established plants.
Straw, wood chips and sawdust don’t add anything to the nitrogen level in the soil. If you’re mulching with these materials, it’s a good idea to add some high nitrogen fertilizer at the same time. One or two cups of fertilizer per 100 square feet of plant area should help you avoid problems.
If you’re using plastic mulch, the polyethylene film we mentioned earlier, you need to add fertilizer first. Use about two pounds of 8-8-8 or 10-10-10 fertilizer for every 100 square feet. Broadcast it over the area and work it down about two or three inches into the soil. This may not seem like much fertilizer, but plastic mulch reduces the amount of fertilizer that leaches out of the root zone of our plants, so you can apply less fertilizer to begin with. That’s one reason why IFAS scientists recommend plastic mulch to commercial vegetable and ornamentals producers.