Mulching serves several purposes. It helps conserve soil moisture by reducing evaporation caused by wind and sun exposure. Mulching also prevents new weed growth, while at the same time smothering weeds that may have started to grow. Mulch is usually organic matter that adds nutrients to the soil, AND makes your garden look nice and tidy.
Mulch can be added over bare ground, or you can put something underneath it like black plastic, newspaper, cardboard, or landscape fabric. Most of these eventually decompose somewhat and need to be replaced. Plastic tends to clump up in some areas and need repair. Experiment to see what works best for your landscape.
Mulch choices include wood chips, shredded bark, shredded leaves (unshredded leaves may can clump together and block air/water flow), composted sawdust (fresh sawdust can cause a nutrient imbalance), straw, gravel, pebbles, and even recycled glass (expensive but gorgeous!)
I don’t recommend using cocoa bean hulls (have a chocolaty aroma when wet which sounds yummy, but may be toxic to pets if eaten). If you don’t have pets, add 2 inches deep over your garden. Hay is full of weed seeds, so avoid its use. Leave pine needles underneath pine trees, (removing them may cause a nutrient deficiency in the trees), and leave grass clippings on your lawn, a process known as grasscycling (this does not cause thatch). I’ll discuss the fabulous-ness of grasscycling in greater detail in a future blog!
Some gardeners may have heard that using eucalyptus mulch is detrimental to plants. According to University research, eucalyptus bark poses no problems and makes an excellent mulch. The same goes for oak, conifer, sycamore and cypress. Oleander bark, however, should be well-composted before use.
When mulching, add about 4-6 inches of material over the area. Most mulches break down over time and need to be replaced every 6 months to 2 years, depending on the mulch chosen.