Compost and Wood Chips Together Not Needed?

Q. If I use compost around plants and trees, do I still place wood mulch over the compost? Is it needed, or redundant?

When the using compost as a fertilizer and soil amendment the compost should be a rich compost full of nutrients. Compost can be a soil amendment, making the soil "fluffier", but if it's rich as well then it will add fertilizer or nutrients to the soil.

A. Regarding fruit trees, wood chips applied 3 to 4 inches deep on the surface of desert soils is always a good idea. It is also a good idea for many traditional landscape plants, like photinia, mock orange and roses, to have wood mulch or wood chips on top of the soil rather than rock. All these plants are healthiest if rich compost is applied as a fertilizer in the spring.

In this demonstration at the University Orchard, compost was added to the soil, the backfill, surrounding the tree roots. The trees were planted the bare root. The woodchip mulch was added to the soil surface in combination with the compost added to the soil. But if compost is added to the top of the soil every year, the woodchip mulch is not necessary for soil improvement. It does a great job however of controlling weeds and conserving moisture around the roots.

            Under some circumstances, some plants get by without wood chip mulch or compost applied as fertilizer. Trees and shrubs that are truly “desert adapted”, or suitable for desert landscapes, can get by without wood chip mulch or compost. All they need is a little bit of fertilizer in early spring every year. These are plants such as mesquite, acacia, Texas ranger and palo verde.

            In desert landscapes, with the surface of the soil covered with small rocks suitable for walking, your only alternative may be feeding plants with fertilizers applied from bags, a.k.a. mineral fertilizers. These can be applied directly to the surface of the soil near drip emitters and watered in.

            Would desert adapted plants be healthier with compost and wood chip mulch? Definitely. But they can tolerate our desert soils without compost and wood chips better than traditional landscape plants.