The University of North Carolina conducted a four year study for the Netherlands Flower Bulb Institute to determine which bulbs might be most reliable as perennials in the U.S.
In addition to developing a list of bulb species and varieties that perennialize in the eastern U.S. -- perform well for at least 3 years -- the researchers discovered that longevity was greatly influenced by fertility. In a presentation of this study, chief researcher and native Michigander Gus DeHertogh stressed that the best time to fertilize was just as the bulbs broke the surface in spring.
Perennial gardens, shrub and tree beds also appreciate fertilizer now. Slow release organic fertilizers are best since their nutrients become available as the soil warms, right in step with plant development.
So break out the fertilizer. Spread it in all your beds.
We fertilize gardens in fall (October or November or whenever we finish work in that bed) and early spring (April; or whenever we start working in that bed). Slow-release organic fertilizers have done the best job for us, so that's what we use. The amount we spread is what will provide 0.2 to 0.3 pounds of nitrogen per 100 square feet of bed.
For the 80-square foot garden you're about to see, we need just under 1/4 pound of nitrogen. (We figured that this way: We scaled down the 100-sq.-ft. max. rate of 0.3 lbs to suit an 80-foot bed: 0.3 X 0.8 = 0.24)
Please don't let your eyes glaze over. In short, we chose to use 6 pounds of Holly Tone by Espoma as it was the best buy.
For how we arrived at that decision, read on.
The most efficient sequence we've found for spring work in a mixed border -- where perennials, bulbs, annuals and woody plants grow together -- is to:
• Prune the woody plants,
• Cut down spent or unwanted parts of herbaceous perennials,
• Remove that debris from the bed and then
• Spread a slow release fertilizer.
We apply the fertilizer before edging, weeding, dividing, planting and mulching because these follow-ups eliminate any need to "scratch in" the fertilizer.
Working this way means taking fewer steps, so we're all for it!
...is a two part process. First, select a product that will correct deficiencies in the soil. Either you have a fertilizer test result with a prescription, such as 4-6-6 ratio of nitrogen - phosphorus - potassium, or you are using a complete, reasonably balanced product such as 5-5-5 or 4-5-5.
Second, you evaluate the fertilizers that will meet the need to determine which is most economic.
Scroll down for what we found in considering four slow-release organic fertilizers currently on the market. For those who are handy with math, we've "shown our work" and know you can take it from there. For everyone else, we've prepared a fertilizer chart that includes even more types of fertilizer and how much ground each will cover, for which types of bed.
Here are the four slow release organic fertilizers we looked at when it came time to fertilize the 80 square foot bed you just saw.
Read on for how much we would need of any one product to cover the entire bed, and how much the nitrogen in that product cost us.
3-9-4 in a 4-lb. bag. Since it's 3% nitrogen (N), we would need 8 pounds. That's two bags at $10.98 each. (.25 pounds N needed ÷ 3% nitrogen = just over 8 pounds of fertilizer.)
The nitrogen in this fertilizer comes to us for $91/pound.
4-3-4 in an 8-lb. bag.
It's 4% nitrogen (N), so we would need 6 pounds: 3/4 of this 8-lb., $10.98 bag. (.25 pounds N needed ÷ 4% nitrogen = just over 6 pounds of fertilizer.)
The nitrogen in this fertilizer comes to us for $34/pound.
3-4-1 in a 3-lb. bag.
It's 3% nitrogen (N), so we would need 8 pounds: nearly 3 bags at $7.48 each. (.25 pounds N needed ÷ 3% nitrogen = just over 8 pounds of fertilizer.) The nitrogen in this fertilizer comes to us for $83/pound.
6-4-6 in a 3-lb. bag.
Since it's 6% nitrogen (N), we would need 4 pounds: one+ bags at $7.98 each. (.25 pounds N needed ÷ 6% nitrogen = just over 4 pounds of fertilizer.)
The nitrogen in this fertilizer comes to us for $44/pound.
It's least expensive per pound of nitrogen, nearly balanced, plus it contains some sulfur to help acidify the soil --- almost always a good thing in our home ground, alkaline Southeast Michigan. A bit more than a third of the nitrogen in it is fast-dissolving which is not ideal for use in cold soil. That portion of the fertilizer may dissolve and drain away before the plant is ready to use it.
For the economy and the sulfur, we choose Holly Tone for this bed.