Few plants give a more beautiful return on your gardening investment than roses. But to get the greatest number of blooms from each of your plants, regularly feeding with a fertilizer designed for roses is essential. One popular method of feeding is with liquid fertilizer. Whether you choose liquid or granular, your fertilizer should contain key nutrients and be applied at proper intervals in the growing season.
Most commercially available plant fertilizers contain some combination of three key nutrients: nitrogen, phosphorous and potassium. Each is essential for healthy plants and bountiful blooms. For roses, nitrogen is needed to produce green growth, but too much can result in leggy plants with few blooms. Phosphorous is key for good root growth and abundant blooms, and potassium encourages vigorous overall growth.
Before You Fertilize
Before applying fertilizer to your rose garden, test the soil to see what the current nutrient and pH levels are. This can be accomplished by obtaining a soil test kit from your local agricultural extension service office and collecting a sample according to the instructions provided. Submit your sample to the indicated testing lab, which will analyze the sample and send you a report detailing the condition of the soil and offering recommendations for enhancing it.
Balance Is Key
Most rose experts agree a fertilizer with balanced amounts of nitrogen, phosphorous and potassium is typically best. The levels of these nutrients is displayed in a series of numbers; a product that contains equal parts of all three might have the numbers 10-10-10 or 12-12-12 on the package. Balance is important in application as well, so feed your plants at regular intervals starting with an initial application just as the plant begins to leaf out.
You may want to consider how much time you want to spend applying fertilizer when choosing between the liquid and granular varieties. Liquid fertilizers are fast-acting but drain from the soil very quickly and require more frequent application--sometimes as often as weekly. Granular and slow-release products are slower-acting but last longer and are usually applied only once or twice per growing season.
Follow Label Directions
To prevent excessive or inadequate feeding of your roses, follow the directions for your product exactly. Too much fertilizer can cause plant stress or "burn," and too little will fail to bring out the best in your roses. Also keep in mind that most roses prefer their foliage dry to discourage black spot and powdery mildew; application of liquid fertilizers should be directed to the base of the plant, rather than the leaves and blooms.