Roses are heavy feeders. A healthy, well-fed rose will produce more blooms and be better equipped to ward off disease and illness.
Roses can survive without being fertilized, but they will struggle. If you don’t have the time to fertilize regularly during the growing season, choose a Species or near-Species rose that is used to growing in the wild without much care. Rosa Mundi, Rosa glauca, Hybrid Rugosas, and large Ramblers like ‘Darlow’s Enigma’ and ‘Paul’s Himalayan Musk’ can fend for themselves. These are once-blooming varieties.
Any gardener wanting to grow repeat-blooming roses should fertilize regularly during the season.
Nutrients Roses Need
All plants need the same nutritional building blocks: Nitrogen (N), Phosphorus (P) and Potassium (K). This is called the N-P-K ratio and is listed on all fertilizer packaging.
As an overview, remember the phrase “Up - Down - All Around.” Nitrogen (N) helps shoots above the ground, Phosphorus (P) helps roots below the ground, and Potassium (K) helps the whole plant all around like a vitamin.
Getting the Right Balance of Nutrients
It’s important to use the right fertilizer for your plants to produce the healthiest plant possible.
If your rose has too much nitrogen, you will have a lush plant with few or no blooms. If it has too little nitrogen, the plant will have yellow leaves, no new growth, and small pale roses.
Too little phosphorus results in dull foliage, dropped leaves, weak flower stems, and buds that will not open.
Lack of potassium produces weak stems, poorly developed buds, and yellow-edged leaves that turn brown.
Roses also need a combination of: Calcium (Ca), Magnesium (Mg), Sulfur (S), Boron (B), Copper (Cu), Iron (Fe), Manganese (Mn) and Zinc (Zn).
That’s a lot of information, and can be daunting to a new gardener. But don’t worry! That’s what we are here for - to help you make the best choices for your plant.
Choosing the Right Fertilizer
Whether you choose organic or inorganic fertilizer is up to you, but look for a balanced, high-quality, rose fertilizer that contains macronutrients as well as micronutrients.
Organic fertilizers include manures, compost, or other plant and animal products. Since the nutrient content is usually low, organic fertilizer needs to be used on a continual basis. While the price for organic fertilizer can be higher, they are better for the environment and make for healthier soil.
Inorganic fertilizers are synthetic fertilizers and are most readily available at stores. They are convenient, more concentrated, and less expensive than their organic counterparts, and come in a variety of forms (liquid, granular, and slow-release). However, inorganic fertilizers do not help the condition of your soil.
When to Fertilize
In spring and summer, begin fertilizing when you have 4 to 6 inches of new growth and can see the first real leaflet with 5 to 7 leaves. When your rose is hungry, it is hungry.
During the first growing season with your rose, feed with a liquid-only fertilizer. Do not use any granular fertilizer as they are too hot and will burn the fine, baby roots, and can potentially kill your rose. We recommend using our Founder’s Fish Fertilizer every 4-6 weeks during the blooming season. Always water in your fertilizer before and after application.
During the following growing seasons, continue to use a liquid fertilizer every 4-6 weeks or granular fertilizer every 4 weeks throughout the growing season. Don’t forget that the use of granular fertilizer during the first growing season will void our one-year warranty. So be sure to only use liquid fertilizer during that first season with your rose.
Late in the fall, apply fertilizers with little or no nitrogen, such as bone meal or rock phosphate, to help promote root growth and next year’s blooms.
Stop fertilizing 6-8 weeks before your first typical frost date.
If you planted your rose in the fall, do not fertilize until next spring when the plant comes out of dormancy.
Already a Pro? Here are a few more fertilizing tips:
- Roses grown in containers need to be fertilized with liquid fertilizers on a more frequent basis.
- Compost and mulch can rob the plant of nitrogen as it decomposes. To counteract this process, you may need to increase the level of nitrogen.
- Your local soil conditions have a lot to do with what nutrients are available to your roses. You may need to make amendments to adjust the pH level of the soil to ensure the best fertilizer uptake.
- Test your soil if you are using the correct fertilizer, have corrected pH levels (between 6.0- 6.5 for roses), and/or are still having a nutritional deficiency. A soil test will pinpoint the problem.