Most roses need regular applications of plant food to reach their full size and produce abundant flowers. Roses prefer a slow-release plant food that is high in phosphorus. For ever-blooming roses, feed regularly with a water-soluble plant food . Not only will regular feedings provide better blooms, but a healthy, well-fed plant is also better able to resist attacks of pests and diseases and to survive severe winter cold.
Feeding your roses will be much easier if you plant them in the right soil conditions. Roses prefer a nice mix of sandy and loamy soil. The rate and frequency of plant food applications and the appropriate plant food to use depend on the type of garden soil. Plants in sandy soil need frequent applications; those in a heavy soil may not need as many. A soil test will help determine the particular balance of the three major nutrients — nitrogen, phosphorus and potassium — that your soil is lacking.
The simplest way to feed your roses is to use Ortho RosePride. RosePride slow-release granules feed roses and flowers for 6 weeks in one easy step. It is absorbed by plant roots and moves systemically up to branches and leaves providing 6 weeks of continual feeding that won’t wash off with rain or watering. The systemic action also provides fertilization to new growth. It is endorsed by the American Rose Society. Simply apply the granules around the base of the plant, mix into the top inch or 2 of soil and water thoroughly.
Dry plant foods
These are worked into the ground and are spread to the roots by watering. To be precise, you will need to know the nutrient balance in your soil to measure the proper amount of dry fertilizer to add.
Liquid plant foods
These are added to water and usually applied to the roots. Foliar liquid plant foods are sprayed onto the leaves, which absorb the nutrients. With some rose types, you should avoid spraying the leaves with a fertilizer as it may cause extra growth through the leaves and not the blooms. Ask your local nursery which type is right for the roses in your garden.
Many rose gardeners rely on a complete (contains nitrogen, phosphorus and potassium) dry plant food and supplemental applications of liquid plant food. Moisten the soil before you apply a plant food; water again after youve applied it to carry the nutrients to the roots.
How often to feed?
Species roses, old roses, and climbers usually need only one application of plant food in the early spring as the buds prepare to burst. Repeat-blooming old roses and climbers will benefit from a second feeding of liquid plant food after the first bloom.
Modern roses need regular feeding to provide energy for growth and blooms. Begin feeeding newly planted roses once they are established, about three to four weeks after planting.
Start feeding older plants after they have been pruned and the new foliage starts to appear.
In regions where winter temperatures drop below 10°F, stop applying plant foods that contain nitrogen six weeks before the anticipated first frost, and apply instead a plant food containing only phosphorus and potassium to strengthen the plant for winter.