A beautiful rose garden is the pinnacle of success in the gardening world. Many gardeners, unfortunately, avoid rose gardening because they know roses are heavy feeders and that many roses are prone to mildew and soil-borne disease. But rose gardening doesn’t have to be so difficult and danger-prone. The foundation of a healthy rose garden is healthy soil, and healthy soil requires good soil amendment.
Good soil amendment improves soil structure, letting it hold and drain water. It allows the soil to have good tilth, which is a loose structure so air can work its way in the soil. Loose, well-amended soil allows earthworms and other beneficial creatures to work their way through the soil, improving its structure with their movement and adding their rich, organic waste.
Roses benefit from soil amendment because nutrients in the soil become more readily available. Organic matter fertilizes roses, while other amendments moderate pH. Good soil is the foundation of a healthy rose plant that is less susceptible to disease and insect damage.
Compost and manure loosen soil and add nutrients, particularly nitrogen. Organic matter slightly contributes acidity. Sand or soil conditioner loosens heavy clay soils, allowing drainage. Bone meal or pulverized crab or oyster shell contributes potassium, phosphorus and calcium. Sand, bone meal and pulverized shell also moderate acidic soils. If soil is particularly alkaline, iron sulphate can be added during planting.
When planting, mix all ingredients in the planting hole to the depth of a shovel. Die-hard gardeners with strong backs sometimes double dig their rose gardens. Double digging mixes in amendments to the depth of two shovels and provides an even deeper amended area for roots to grow in. This is especially useful if soil is particularly poor or compacted. Soil amendments should account for one-third of the new soil mix. If your soil is particularly dense, one-half would not be too much.
Replenishing organic mulch each spring improves soil structure and nutrition by breaking down over the growing season. Liquid kelp meal and fish emulsion fertilize roses and help break down organic matter in the soil. Granular organic fertilizer often contains organic elements, such as cocoa meal, which break down over time, improving soil structure. Scratch granular fertilizer and additives into the mulch.