Changes in the soil will improve the performance of plants and will give you a larger group to choose from. Changing and preparing soil are fundamental building blocks of agriculture and horticulture. Soil turn over can be done with a rototiller or by hand with a spade or digging fork. The organic material can be composted manure, leaf compost or peat moss, two to three inches deep. The organic material should be evenly mixed into the soil.
Organic material does a number of good things for the soil.
It improves soil's structure, increasing the soil ability to hold moisture, and promoting a freer flow of oxygen into the soil. The organic material will also aid in the break-down of tied up minerals in our clay soils which can increase fertility. Chemical and granular fertilizers can be added to flower beds at this time. The use of chemical fertilizers in vegetable is a personal choice. If you decide to use them, do it early in the year so by harvest any residue is reduced.