Fast Release to Control Release Fertilizer Analysis

Based on the success of the daylilies and roses in 2022 when we began using 13-6-6 Control Release urea blend from GreenPoint Ag rather than the “Concoction”, and the desire to simplify/reduce repetitive feeding of all plants, in Spring 2023 we began feeding roses, crapes, and others with the time release.

The two feedings where the quantity applied was somewhat controlled was here where the amount spread per square foot in March 2022 was based on the circular Lady Daylily bed at 75 SF where we spread a little more than a quart evenly over the area. That will be the maximum target for the future adjusted based on rainfall that would wash out the fast acting 5.54%.

The following table was prepared to evaluate how frequently to reapply that mix to be equivalent to traditional bi-weekly feeding for the crapes and monthly feeding of the roses of fast-acting fertilizer.

Nitrogen componentMarchAprilMayJuneJulyAugSeptOctNovDec
5.45-6-65.455.455.455.455.455.455.455.45
7.54 90 day PCU2.52.52.5
2.52.52.5
2.52.52.5
2.52.52.5
2.52.52.5
2.52.52.5
2.52.52.5
2.52.52.5
Total Nitrogen8.010.513.013.013.013.013.013.05.02.5

The logic in the table is that spreading monthly will apply the immediate release of 5.45% each month plus one-third of the 7.54% component for that month plus the one-third part of the 7.54% from the previous two months. The control release portions for each month overlaps with previous months and adds to the overall release.

A monthly application of 13-6-6 TCU 90 Day will be the equivalent of spreading 13-13-13 after the third month. We likely should stop applications after September so there is only a small release in November.

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