Similar to any other flowering plants, it is natural that roses also require adequate food for growing and blooming as per the growers’ expectations. Rose plants produce alluring and aromatic blooms and they also have more nutritional requirements compared to several other flowering plants. While the soil and the air naturally provide them with small amounts of nutrients, it is necessary to provide the plants with necessary supplements to ensure the optimal performance of the plants. Therefore, it is important not only to provide the plants with appropriate nutrients but also ensure that they are provided at the appropriate time and that they have the correct formulation for roses.
Typically, fertilizers enclose three elements that are essential for the growth of roses – nitrogen, potassium, and phosphorus. Nitrogen is essential for the growth of the plant’s leaves and stems. At the same time, it also imparts the plants their deep green color, in addition to promoting the growth of the plants in early spring. Similarly, potassium facilitates regulating the metabolism of the roses and also helps them to become hardy. Potassium is also necessary for the plant’s vigor, disease resistance and the wonderful hues of their blooms. Phosphorus, on the other hand, promotes the growth of roots and flower production. This element is also necessary for photosynthesis by the plants. If a fertilizer contains all these three elements, it is called a complete fertilizer.
As different plants have dissimilar nutritional requirements, various types of fertilizers are available in the market – each having a different percentage of nitrogen, phosphorus, and potassium. A standard fertilizer will come in the formulation of 5-10-5, meaning it will contain 5% nitrogen, 10% phosphorus, and 5% potassium. The remaining 80% of the fertilizer will comprise inert (inactive) materials that will help in the even distribution of these vital elements. You will find that the product labels will always mention these percentages in the same order. In addition to this formulation, rose fertilizers are also found in two other formulations – 8-12-4 and 5-10-10 (the first being the percentage of nitrogen, the second mentioning the percentage of phosphorus and the last denoting the percentage of potassium).
Similar to several other flowering shrubs, roses also flourish optimally when you apply a fertilizer that contains nitrogen, phosphorus, and potassium in the proportion of either 1:2:1 or 1:2:2 or 2:3:1. When the proportion of nitrogen is relatively less in fertilizers, it helps the plants to produce fewer lush leaves at the cost of their exquisite flowers.
Many gardeners use special fertilizers like super phosphate (0-20-0) as well as tripe super phosphate (0-45-0) at the time of planting with a view to promoting the growth of the roots. As evident from their formulations, these special fertilizers only provide the plants with phosphorus.
Generally, there are two types of fertilizers – organic and inorganic. The fertilizers that are said to be organic contain carbon and may be both natural and man-made (synthetic). There are a number of organic fertilizers like cottonseed meal, bone meal, and fish emulsions. All these are actually minimally processed vegetable or animal by-products. On the other hand, further elaborate processes are used to manufacture synthetic fertilizers like IBDU (scientific name isobutylene di-urea) as well as sulfur coated urea. Both types of organic fertilizers are available in the form of granules, powders, particles and even as liquids.
Most of us are aware that inorganic fertilizers are basically comprised synthetic or artificially made products and, hence, do not contain any organic substance. These fertilizers are made from mineral salts, usually ammonium nitrate, potassium nitrate, ammonium phosphate, calcium nitrate, ammonium sulfate, potassium sulfate and potassium chloride. In their unadulterated form, these inorganic fertilizers are solids. However, they are also available in the form of solutions.
There is a number of organic as well as inorganic fertilizers that are called slow-release fertilizers, as they release the nutrients contained by them over a prolonged period, generally taking anything between three and nine months. Slow-release fertilizers are actually more convenient for gardeners compared to the standard fertilizers, as you do not have to apply them too frequently. While a number of slow-release fertilizers need to be applied just once in a year, either during the end of winter or at the onset of spring, there are other slow-release fertilizers that need to be applied more often. At times, the release of nutrients from these fertilizers is activated by the moisture retained in the soil. On other occasions, the release of nutrients may be activated by the high temperature of the soil.
So, how do you determine if a fertilizer is of the slow-release variety? The best way to ascertain this is to go through the product label and find the proportion of water-insoluble nitrogen contained in the fertilizer. If you find that the fertilizer contains 30 percent or more water insoluble nitrogen, you should consider it to be a slow release type.
Some products come with labels that clearly mention the months that the fertilizers will last. If applying fertilizers only once a year is convenient to you, you should opt for a product that will release the nutrients all through the year, covering the entire growing cycle of your roses – irrespective of whether the growing season lasts for three months or four months or six months or nine months. It is worth mentioning here that the slow-release fertilizers do not contain the vital trace elements that are found is several other normal fertilizers. Therefore, it may be necessary to provide the plants with supplements containing these trace elements.
Then again, you have the option to use dry fertilizers or liquid fertilizers for your plants. A number of normal organic liquid fertilizers, for instance, fish emulsions, are available in the market. Precisely speaking, the expression liquid fertilizers generally denotes dry or liquid inorganic fertilizer concentrates that are soluble in water and are blended with water prior to applying them. Usually, the formulations of such fertilizers are 15-30-15 or 20-20-20. As this type of fertilizers is soluble in water, they act very rapidly and release the nutrients contained by them very fast. In fact, such liquid fertilizers are a boom for people growing roses in containers. However, as these fertilizers are water soluble, it is essential to water the plants very often after feeding them. On the other hand, if you are using dry fertilizers and water the plants frequently, it may cause the fertilizers to be washed away even before they can start working.
However, liquid fertilizers are not as suitable provided you are growing roses in the ground. This is because you need to apply liquid fertilizers more frequently – at least twice in a fortnight or every two weeks. Hence, liquid fertilizers are not as suitable as the dry fertilizers. In fact, most gardeners use them in the form of supplements for roses grown in the garden. While choosing a fertilizer for your roses grown in your garden, you should always opt for a slow-release fertilizer as this will save you a lot of your effort and time. Alternatively, you can use a fertilizer that is a combination of organic and inorganic nourishment’s – this is perhaps the best option for gardeners growing roses in the ground. At the same time, if you desire you can use liquid fertilizers in the form of a supplement for your garden roses. On the other hand, liquid fertilizers are the best option for people growing roses in containers.
How and When to Fertilize
It is extremely important that you apply fertilizers to rose plants at the appropriate time. This is important because the soil should contain enough nutrients at a time when the plants will be requiring them most, especially during the phase when they are in active growth mode and their flowering season. The time for this will, however, vary depending on the climate. However, the right time for applying fertilizers begin with the initial growth signs during the later part of winter or the beginning of spring and continues till the cool weather during the fall slows down the growth of the plants. At the same time, it is essential to apply the proper amount of fertilizer, depending on the soil type as well as the variety and size of the flowers. The amount of fertilizer that you need to apply is also subject to the duration of the plants’ growing season and the potential competition from other plants growing close by.
If you are planning to grow roses or are already growing them, you should know that these plants need to be fertilized quite often. It is advisable that you use a rose food or a complete fertilizer having an N-P-K ratio of 1:2:1, 2:3:1 or 1:2:2. At the same time, it is essential to feed the roses soon after the plants are pruned, when the plants have completed their first blooming period and approximately two months prior to the first expected fall frost in your region. On the other hand, gardeners who desire to cultivate roses similar to those of exhibition-size should feed the plants once every month during the period between the onset of spring and end summer or beginning of fall, subject to the duration of the plants’ growing season. You may also apply liquid fertilizers just before any rose show as this will help in producing improved flowers.
In case it is necessary to adjust the soil pH, the job should be undertaken about a month prior to fertilizing the soil with a view to producing the best possible soil pH for roses – about 6.5. The fertilizer you apply will be more effective when the absorption of nutrients is more efficient at this pH level.