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Applying Compost

Amend Soil with Finished Compost


On established lawns, apply compost once a year in layers 1/4 to 1/2 inch thick. Water well.

To prepare soil for a new lawn, till 4 inches of compost into 6 inches of soil.

Trees and Shrubs

Lay 1" compost around trees from one foot away from trunk out past the drip line. A 2" layer should be used for shrubs. Apply once per year.

To prepare soil for new shrubs, till the soil to a depth of 8 - 10 inches. The depth should be at least twice the width of the root ball. Apply a layer of 4 inches of compost and mix thoroughly into soil. If soil is very poor use 6 inches of compost instead.


Lay 1/2 to 1" compost on top of soil. If possible, till 2 - 4" into the top 10" soil. In large fields, apply between 900 and 1200 lbs. per acre as needed, depending on the current health of the soil.

To establish a new garden or prepare garden for planting, till the soil to a depth of 8 - 10 inches. Apply a layer of 4 inches of compost and mix thoroughly into soil. If soil is very poor use 6 inches of compost instead, mixing much of the additional compost into the top 3 - 4" of soil.

Potted Plants

Do not plant in pure compost. To root properly, plants must have the texture provided by soil. Your potting mix may be 1/4 to 1/3 compost. The remainder may be good potting soil. Many organic gardening books have "recipes" for potting soil which recommend a combination of compost, castings, potting soil, and other organic materials.

Amend Soil with Organic Materials

This section covers soil amendment by addition of organic materials that are not yet fully composted. Such materials should not be added into soil which contains living plants -- see the discussion on nitrogen draft in the next section. Organic materials may be added directly into the ground and allowed to compost there if the ground will remain fallow for an appropriate time -- at least 6 months. For instance, organic materials may be tilled into a garden after the fall harvest and left fallow at least 6 months until spring planting. Because the appropriate mass is not achieved, composting in the ground takes longer than composting in a pile.

To prepare for a new lawn or garden, till 2 inches of compost into the top 6 inches of soil. Be sure to cover the ground with several inches of mulch.

Mulch with Organic Materials

Mulch is matter that is placed on top of the ground (NOT tilled into the ground) as a covering. All bare soil should have a cover of mulch. Although some like to mulch for the appearance, the real purpose of mulch is to protect the health of the soil. Mulch lessens the effect of extreme temperatures. During summer months bare soil may reach 120 degrees F, but if that same soil were mulched, it would reach about 85 degrees F. In addition, mulch increases moisture retention, prevents top soil from washing away, and reduces soil compaction. One of the great benefits of mulch is that it shades out weeds. By covering the ground, weeds cannot get enough light to grow. The few that do survive are so weak, they can be easily removed. Before you lay down mulch, cover the ground first with newspaper. This will make it even harder for weeds to grow.

In addition to partially completed compost, there are many other organic materials which may be used as mulch: pine needles, various types of wood bark or chips, pecan or peanut shells, and shredded leaves.

Partially Completed Compost, Nitrogen Draft and the Forest Floor

There is controversy as to whether partially completed compost should be used as mulch. Opinions range from
"Never use compost that is not completely finished. After compost is finished, let it cure for several weeks to be sure the process is complete."
"One of the best mulches is partially decomposed compost."
Proponents against this practice claim that the compost will rob soil and existing plants to obtain nitrogen needed to complete composting. Other concerns are that there may be pathogens in the bacteria that have not yet been killed by exposure to the hot center of the pile, and that acids in the materials may be released as they compost and harm plant roots. Most experts agree that nitrogen will be stolen for composting if the materials are tilled INTO THE GROUND. The debate is whether or not this is true if the matter is laid on top of the soil. Other experts, including Howard Garrett (Texas Organic Gardening, p. 98) say that, as long as the partially decomposed matter stays on top of the soil, there is no damaging nitrogen draft.

For my own use, I believe it is a good mulch. I base this decision on the forest floor. The forest floor, from the bottom layer up, consists of soil, finished compost, partially finished compost, barely-started compost, and fresh organic materials. If it is OK for nature, it is OK for me. You must decide for yourself on this issue.


Place compost around trees or shrubs from one foot from trunk, extending out past the drip line. Don't place mulch right up against trunk. Recommendations as to the depth of mulch varies from 2 - 6 inches. I usually try to get it about 4 inches deep when I lay it down once a year. When I mulch the next year, I put the new mulch on top of the previous year's mulch, which is in the process of decomposing. An added benefit to mulching around trees is that the ground does not get compacted, nor the tree trunk damaged from mowing and weed-eating.

Annuals and Perennials

Partially completed compost can make a mulch for ornamental plants. Recommendations range from 1/2 to 3 inches over entire bed. Don't place mulch right up against plants.


Partially completed compost can make a mulch for food crops. Apply 1/2 to 1 inch over entire bed. Don't place mulch right up against plants.

Finished compost adds nutrients and organic matter to the soil,
improving its texture and increasing its ability to hold air and water.
Because it doesn't burn plant roots, large quantities of compost
can be applied to the soil at any time.

Soil Improvement

Try digging several centimetres of finished compost into a flower
bed or vegetable garden before planting. How much you use will
depend on how much you have available: the soil can use it all.

You can also give trees, shrubs, and nursery seedlings a good start
by planting them in half-and-half soil and compost. New lawns will
develop healthy roots to keep them green, if compost is dug into
the soil before the grass seed is applied. When an established lawn
suffers winter-kill, working some compost into the bald spots
before seeding again is another good idea.

Top Dressing

Treating lawns with a half-inch of compost serves as a very
effective feeding when the ground has dried in the spring. By sifting
the compost first, you can remove any unattractive large pieces or
materials that may not be fully decomposed.

Side Dressing

You can also apply compost as a spot fertilizer. Scratch it lightly
into the top few inches of soil around the plant that needs a boost,
and water deeply.

Compost "Tea"

Here's a tidy way to supply compostnutrients to house plants or to spot-fertilizeseedlings. Soak a burlap bag or old pillowcase of compost in a pail of water until the liquid is tea-coloured. Or stir one part compost into three parts water and pour off the "tea."Using this liquid to water plants makes a difference, particularly inthe middle of the warm growing season.


Mulching should be done latein the spring when the groundis thoroughly warmed, but before summer's heat, in order toconserve moisture. Spread several inches of compost on top of the soil around trees and shrubs, from near the base of the trunk out to the dripline. You can also mulch around vegetables and flowers as soon as the plants are several inches high, to keep roots cool and discourage weed growth.

Potting Soil

House plants, window boxes and hanging baskets will all benefit
from a potting soil mixed with sifted compost. Compost alone can
be used for growing vegetables in containers, and for starting
plants from seed. For indoor use, you may want to sterilize
compost in the oven for an hour at 95oC (200oF) -- but don't be
alarmed by the (temporary) strong smell.

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