Your Complete Guide to Fertilizing Roses for Beautiful, Vivid Flowers
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Roses are one of the most popular flowers in the world– the fragrant multi-petal beauties come in a variety of shades and sizes, making them perfect for just about any celebration or centerpiece arrangement. Despite their popularity, roses have a reputation for being difficult to manage; they are heavy eaters, which means that they require a significant amount of nutrients and frequent fertilization. “The three main nutrients roses need from fertilizers are nitrogen, phosphorus and potassium,” says Kristen Smith, plant coordinator and rose product manager at Star® roses and plants. She also notes that roses require a range of micronutrients, including iron, calcium, and magnesium. When given a fertilizer with the necessary elements, the flowering shrub is actually quite easy to maintain and will produce large, beautiful flowers year after year.
There are several types of rose fertilizer.
In addition to containing the aforementioned elements key nutrients and micronutrients, the rose-based fertilizer should have a pH of around six to seven, Smith says. “A pH outside this ideal range will make it more difficult for the rose to absorb certain nutrients, even if the soil is rich in nutrients,” she adds. You’ll also find a few different iterations when you shop around, as rose fertilizer comes in many forms. There’s the liquid fertilizer, which is often used the first year (it’s less likely to burn new roots), says Jimmy Speas, president of the Winston-Salem Rose Society; it is also useful during times of drought or summer when the heat can quickly warm the soil or plants. Liquid fertilizer can be applied as frequently as every two weeks during the growing season, but be sure to follow the manufacturer’s directions for quantity and frequency. Beyond liquid, Smith says there are also granular or slow-release feeds, which can be added once at the start of the season and will continuously release fertilizer into the soil over a longer period of time.
You will find organic and non-organic options.
Liquid and granular fertilizers are available in organic and inorganic formulations. “Organic fertilizers come from natural sources such as manure, fish emulsion, bone meal or compost“Smith says.” Inorganic fertilizer is man-made from synthetic chemicals. “While each contains the necessary nutrients roses need in order to bloom, Speas is a fan of organic options. “Organic produce feeds on microorganisms that allow roses to use nutrients in the soil for food,” he explains. This in turn improves the color of the bloom and reduces the risk of root and leaf scorch. Synthetic options, on the other hand, are generally offered at a lower price and require less frequent application; they are more concentrated than the organic offerings. To prevent root burns, it’s best to add inorganic fertilizers to moist soil rather than dry soil, but follow the manufacturer’s label for step-by-step instructions.
Have your soil tested.
Many companies offer rose-based fertilizers in a 10-10-10 ratio of nitrogen, phosphorus and potassium, explains Speas. However, he recommends have your soil tested before choosing a formula. This will let you know if your soil needs more or less of a required nutrient. “If a soil test shows that your nitrogen level is good but your phosphorus and potassium can use more, there is 5-10-10 or 10-20-20, which means the nitrogen is half as much as the other two, ”he says. Speas also notes that if you can’t find rose fertilizer with the specific percentage your soil needs, find one that lists other nutrients at a lower concentration than you need.
Here’s how and when to fertilize roses.
When it comes to fertilize roses, Speas says growers should “focus on what’s going on below the ground more than what’s going on above,” noting that forming a strong root system is key to successful flowering. Newly planted bushes need fertilizers that are high in phosphorus, which promotes root growth, more than they need food that is high in nitrogen. Established roses will not need to be fertilized until early spring, as they begin to defoliate. Wait until you see about six inches of new growth to begin. If the roses are very dry, water them first before feeding them; Smith says this will prevent the flower from absorbing nutrients too quickly. Fertilize the perennial regularly throughout its growing season (approximately every two to four weeks depending on the type of fertilizer used). Stop feeding your roses in late summer when they start to prepare for winter dormancy. “Fertilizing late in the season can encourage new, unnecessary tender growth that can be damaged by cold snaps in the fall,” says Smith. “This damaged growth can then be susceptible to further damage from the pests.” You can, however, add organic material like compost or rotten manure as a fertilizer during the winter when the roses are dormant.
Our best fertilizer choices.
There are plenty of rose fertilizers to choose from, but to help keep the noise down, we’ve asked our experts to share their favorites. Speas says many growers use Mills Magic ($ 29.99, millsmix.com). The 100% natural product was formulated by Ted Mills, an accredited rosarian consultant and rose show judge for the American Rose Society. The mixture includes a combination of alfalfa meal, blood meal, fermented citrus peels, cottonseed meal, feather meal, bone meal and potassium-magnesia sulfate. Another great option is Down to Earth Organic Rose and Flower Fertilizer. ($ 17.84, amazon.com). The special blend is derived from natural ingredients and provides roses with all three essential nutrients, as well as trace elements for healthy plant stock. For a liquid fertilizer, we recommend Neptune’s Harvest Fish Fertilizer ($ 38.18, amazon.com). It contains all of the macronutrients naturally found in fish and is made by a process that protects the vitamins, amino acids, enzymes, and growth hormones necessary for the development of beautiful flowers.