Using Compost In Gardens
Homeowners who have flower or vegetable gardens usually give them top priority when it comes to deciding where to use compost. It is in the garden that the benefits of a soil rich in humus are most obvious and appreciated. The plants in gardens are intended to either be decorative or productive (or both) and soil enriched with compost promotes the good plant health required for these qualities. As with compost on the lawn, the main question here is how much compost is appropriate to maintain healthy garden soil? The answer to that question affects the strategy for spreading it in the garden.
Lots of Compost -- A garden soil that has been attended to for many years, has been mulched well, and has had some organic material added to it from time to time probably has a decent humus content. Such soil will require only about a ¼ to 1/2 inch layer of compost every year or two to maintain its quality. A garden soil that seems to need frequent watering, that produces fewer crops or less vigorous plants than normal may have insufficient humus content. In this case it may be necessary to spread a 1 inch layer for a year or two to rehabilitate it. How much compost is available to do the soil maintenance and soil rehabilitation around the yard has a lot to do with how it is used.
Not Much Compost -- If the supply of compost is really limited, it must be used more sparingly. Topdressing is out of the question because it requires more compost than is available. An alternative way to introduce compost into the soil is called "side dressing". Rather than spread it all over, when you side dress, you strategically place compost just around certain plants or along certain rows or groups of plants. The idea is to use compost in small amounts, targeting particular plants that are young or look poorly.
Here also, the goal is to apply from ¼ to 1/2 inch of compost, but it is put on a limited area in close proximity to certain plants. To side dress a plant, lay a circle of compost on the bare soil around the plant. Start it about an inch away from its stem and spread it out to the drip line of its foliage, or the width of its foliage. Scratch the compost into the soil just a bit with a trowel or hand cultivator, taking care not to disturb plant roots. If plants are particularly shallow rooted like azaleas and many annual flowers, it is best to just leave the compost on the soil surface and let the rain and the soil microbes take it below the surface. Side dressing is best done in the late spring and early summer so the rapidly growing plants can get the most benefit from this amendment when they need it most.
Starting Seedlings Indoors -- A fungal disease called "damping off" is a common problem of seedlings that are started indoors. Two measures will reduce problems with this fungus. First, use compost made at low temperatures (the slow method) in the potting soil that the seeds are planted in. A good mix is about 1/3 compost, 1/3 vermiculite, 1/3 perlite or coarse sand. Compost made the slow way suppresses damping off spores. Second, when the seedlings appear, always be sure they have good air circulation. The best way to do this is to set up a fan to blow a very light breeze over the flats or pots of newly sprouted seeds. Damping off will seldom attack a seedling that is well ventilated.