University of Maryland Extension

March Soil, Compost, Fertilizer, and Mulch Tips

garden fork in soil

Use a garden fork to loosen and aerate topsoil and subsoil.

(More tips from HGIC)

Soil

  • Avoid the temptation to turn over or dig into wet soil. Tilling wet soil can cause it to become cloddy and brick hard when it dries out. How do you know when your soil can be turned or tilled? One test is to form a clump of your soil into a ball. Bounce it up and down in your hand a few times. If it breaks apart easily it’s probably OK to dig!
  • Test your soil if you have not had your lawn or garden soil tested for the past 3-4 years. Be prepared to raise soil pH with lime or lower soil pH with iron sulfate and/or elemental sulfur this spring according to the written recommendations you receive. For more information on soil testing see:
  • Poor, compacted soils can be improved through the generous addition of organic matter. This spring, spade or till in a 6-8 inch layer of compost for new flower and vegetable garden beds.

  • If you want to grow vegetables, flowers or herbs next spring and your soil is especially poor, consider building a raised bed and fill it with a purchased mixture of topsoil and leaf compost.

Compost

  • Your compost pile will begin to come back to life this month.If your pile dries out, add water so that the materials have the moisture content of a wrung-out sponge. If your pile is overly wet and smelly, mix in some dry materials high in carbon, like shredded newspaper, straw or shredded leaves. Be sure to bury kitchen scraps deep inside your outdoor compost pile to prevent offensive odors that might also attract rodents.
  • Keep sticks, roots, and woody stems out of your compost pile. They take too long to breakdown and make it difficult to turn the ingredients. The composting process will slow down considerably when temperatures dip below 50 degrees F. Turning the pile every 2 weeks will hasten the breakdown process.
  • Compost piles should be at least one cubic yard in volume to heat up properly. An even mixture of green, high nitrogen and brown, high carbon materials is necessary for rapid composting. Grass clippings and spent plants from the flower and vegetable garden provide a good source of high nitrogen, green materials for the compost pile. Fallen leaves and old straw mulch are good sources of high carbon, brown materials. Shred your materials with a lawnmower, string trimmer or machete to speed-up the breakdown process. 
  • Finished compost is the very best starter material for a compost pile because it contains nitrogen and a huge number of microbes that help transform organic matter into compost. It is not necessary to buy a bioactivator to add to the compost pile.It is also not necessary to add soil or lime to a compost pile. Consider placing a tarp or lid over your pile to prevent waterlogging and nutrient leaching over the fall and winter. Kitchen scraps thrown on top of compost piles may attract pest animals. It is best to bury these scraps in the middle of your compost pile.

Fertilizer

  • Many home gardeners overuse PDF fertilizers. This results in excessive nutrient runoff and water pollution. Over-fertilization especially with fertilizers high in nitrogen can also lead to succulent, weak plant growth that encourages sucking insect pests like scales, aphids, and adelgids. Most landscape plants get adequate nutrition from a healthy soil rich with organic matter.
  • Fruit trees are fertilized in the spring. Landscape trees are usually fertilized after they drop their leaves in the fall. Mature shade trees do not typically need to be fertilized at all.
  • Plants that typically benefit the most from fertilizer are those that are producing either flowers or fruits such as flowering annuals and vegetables. Apply a soluble fertilizer to the root system and or foliage to encourage quick establishment in spring. Compost tea, fish emulsion, seaweed extracts, and soluble plant foods can all be used according to label directions. Additional fertilizers are often unnecessary with fertile soils in well-managed beds that receive yearly applications of at least one inch of compost.
  • Whenever broadcasting granular fertilizers near sidewalks and drives always sweep them from paved surfaces to prevent them from washing into storm drains and waterways.

Mulch

  • Keep wood mulches away from the house. Mulches should be applied only 2-3 inches deep around ornamental plants and kept away from shrub and tree trunks. Mature trees do not benefit from being mulched, except to keep mowers away from the trunk.
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