Finished compost is the product of up to several years of outdoor ripening. Microbial activity breaks down raw materials such as yard waste and kitchen scraps into a rich humus. The finished compost improves soil tilth, making nutrients and water easily accessed by growing plants. The compost itself provides nutrients. A compost bin or tumbler speeds the process and gives the gardener convenient access to compost for the rose bed.
Raw or cooked oatmeal contributes organic matter to the compost as it breaks down over time. Add either raw oatmeal that has outlived its shelf life or unadulterated leftover cooked oatmeal to the tumbler or heap.
Incorporate compost into the planting holes of new rose beds. Spread compost over an existing rose bed beginning early in the growing season, working a layer into the top 1 or 2 inches of soil. Work lightly to avoid damaging surface feeder roots close to the bases of the rosebushes.