Knowing what fertilizers to use and how to apply them is critical to getting your roses started off in the right direction this spring.
Basically, there are two groups of fertilizers - synthetic and organic. Quite honestly, the plant doesn't know the difference between the two. It's only interested in the ions it can absorb through the roots and leaves. But choosing the right fertilizer and applying it correctly has a significant impact on the hardiness and vigor of your plant.
For the purpose of discussion, synthetic fertilizers are those that are nitrate-based. Often, they contain ammonium nitrate. Nitrates are the form of nitrogen used by the plant. Conversely, organic fertilizers are nitrite-based and must be broken down by microbial activity. After nitrifying bacteria convert the nitrites into nitrates, the plant "gets fed." This is why I use the expression, "Synthetic fertilizers feed the plant. Organic fertilizers feed the soil... which in turn feeds the plant."
Nitrate-based fertilizers can cause serious damage to roses if applied incorrectly or too early in the season. These fertilizers often cause a spurt of tender, young growth - growth that has not had sufficient time to harden before winter's freezing weather is complete. Die-back is often the result.
Likewise, applying these fertilizers creates an over-concentration of nitrogen in the growth tips. This nitrogen attracts plant sucking pests, like aphids, and increases your workload in gardening chores.
Finally, applying nitrate-based fertilizers does little to improve the soil because it shortcuts The Nitrogen Cycle. And in some cases, these fertilizers may actually damage the soil because many are attached to a salt which is not easily leached away.
Because of this, most every rosarian adds organic supplements as a "tonic" to their garden at the beginning of the rose growing season. The best time for this activity is just after pruning. Before applying your tonic, it's a good idea to see what is missing (or what has been consumed) from the garden. This is easily done with an inexpensive soil test kit. Then, modify your tonic to provide extra supplements as needed.
I have attached a repost of my "Spring and Fall Tonic" to help get you started. It's what works for me... in my rose garden... with my soil conditions. Feel free to use it, improve upon it, or just ignore it.
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