Nourish: Tips on Applying Compost and Mulch

Flower and Garden Beds

Cover your planting area with a one- to three-inch layer of compost. Incorporate it thoroughly using a spade, hoe, or rototiller with the top 5-6 inches of soil. If necessary, repeat this process one or more times. Rake the soil smooth and level. Water thoroughly after planting. Condition the soil this way every one to two years depending on overall soil quality. Remember, compost can also be used as mulch.

New Grass or Turf

Depending on the results of your soil test, apply a one to three inch layer of compost to the soil and incorporate it to a depth of five to seven inches. Apply seed to amended area then rake and water.

Turf Maintenance

Apply a one-quarter to one-half inch layer of compost evenly to the grass or turf surface. Add the additional benefit of core aeration to your turf maintenance program if the soil is overly compacted – if it is difficult to push a screwdriver into your lawn it needs some aeration. The compost will stimulate new root growth.

Trees and Shrubs

Dig a hole the same depth as the root ball. Mix one part compost with three parts soil obtained from the planting hole. Place the tree or shrub into the planting hole, placing 2” of the amended soil in the bottom of the hole and around the root ball. Water thoroughly then firm up the soil around the base of the plant.

Topsoil Upgrade 

Mix twenty to fifty percent compost into your existing soil. Adjust your blend depending on the condition of the existing soil type and plantings that you will be installing.

Did You Know?

University of Washington research found the best plant growth results with 5 inches of pure compost added to the top 8 inches of existing unimproved soil for a total mixture depth of 13 inches, plus another 2 inches of compost as top dressing mulch. This soil improvement strategy increased plant biomass by between 580 percent and 860 percent without the use of chemical fertilizer. The improved soil also held twice as much water as the unimproved soil.