Can I just use the all purpose 15-30-15 fertilizer for bulbs (tulips, daffodils, iris, crocus, etc.)? That's all I have right now and I don't know if I have to use the fertilizer specially designed for bulbs. I don't know if it really makes a difference... Thanks!
To determine the type of fertilizer you need, you not only need to know the type of plant but also the type of soil. The amount of nutrients available for plant uptake vary based on the type of soil as a result of soil-fertilizer interactions. However, generally speaking, an all purpose fertilizer is sufficient but not optimal for bulb growth (bulb fertilizer is usually 10-10-10). In the end I suggest that you use trial and error to determine the type and amount of fertilizer that makes your bulbs grow/bloom best. Hope this helps, Linda
Instead of wasting time and money, possibly poisoning your soil (and contributing to water pollution) with unneeded fertilizer applications sample your soil and have it tested to get an idea what the situation is first.
Most any recognized complete vegetable food fertilizer will work just fine for Spring bulbs. A 15-30-15 is quite alright for these bulbs. I would use one teaspoon per Daffodil and Tulip bulb. One half a teaspoon for each Crocus and Dutch Iris bulb. A 10-10-10 is just fine also. I use a 6-12-6 every year for my bulbs sprinkled on top of the soil for an existing planting. Placed at the bottom of the hole then covered with 1-2 inches of fill soil and then the bulb placed on top of the fill soil and then covered over for a new planting. Then water the fertilizer in by hose, for either naturalized or new planting, just to wet it and then let the Winter rains do the rest. Jim
Nobody should be making fertilizer applications (or specific recommendations) without at least seeing a soil analysis report for the site in question. Phosphorus, in particular is often overapplied, can produce deleterious effects. http://www.puyallup.wsu.edu/~Linda Chalker-Scott/Horticultural Myths_files/Myths/Phosphate.pdf
