Recently many gardeners have been asking, “Can I still use potassium phosphate at this time of year when the buds of roses are starting to show color? Some people say that overuse of potassium phosphate can lead to shorter blooms, is this true?” This leaves many hobbyists confused and wondering if they should continue to use it.
Understanding Potassium Phosphate
Potassium dihydrogen phosphate is a common water-soluble phosphate and potassium fertilizer that is widely used in home flower gardening, especially to promote flowering and enhance root health. While some gardeners have reported significant results from its use, others have mentioned that after using potassium dihydrogen phosphate, the growth of roses has stagnated instead. The difference between this depends largely on the timing and concentration of use.
Ratio of Nitrogen, Phosphorus and Potassium in Flower Duo Fertilizer
You may be more familiar with Flower Duo #1 and #2, knowing that #1 is for general growth stages, while #2 is a flower promoting fertilizer. The main difference between these two fertilizers is the ratio of their active ingredients: the ratio of nitrogen, phosphorus and potassium in Flower Duo 1 is 1:1:1, while the ratio in Flower Duo 2 is 1:3:2, which significantly increases the content of phosphorus and potassium, which helps the root system to be strong and the flower buds to develop.
Simply put, potassium phosphate is one of the key ingredients in making these water-soluble fertilizers. If you remove the nitrogen from Flower Duo 2, you get potassium dihydrogen phosphate.
The Best Time to Use Potassium Phosphate and Potential Risks
Moderate amounts of nitrogen, phosphorus, and potassium are needed throughout the plant’s growth period, but the needs vary at different stages of growth. For example, more nitrogen is needed during leaf growth, while an increased proportion of phosphorus and potassium is needed during bud formation to support bud development.
However, “heavy” use does not mean unlimited increases in concentration. Over-fertilization can lead to fertilizer damage, which can affect plant health. Therefore, a proper fertilization strategy is essential.
Potassium dihydrogen phosphate in relation to the flowering stage of roses
When roses enter the bud color development stage, many people worry that continued application of potassium dihydrogen phosphate will shorten the flowering period. In fact, instead of shortening the flowering period, the right amount of potassium phosphate fertilizer applied at the right time will help to prolong the flowering period and ensure that all the buds receive enough nutrients to open.
For flowers like hydrangeas, which bloom only once a year, it is acceptable to stop fertilizing after the buds show color, but for roses, it is very important to continue to follow up with phosphate and potash fertilizers until the smallest buds show color.