As someone new to gardening, I follow established guidelines & practices from here, universities Ag. extension services, National Societies etc.. . . somewhat blindly! I am probably missing something. I have two types of fall-planted bulbs: spring flowering (daffodils, hyacinths AND grape hyacinths, tulips, crocus, allium) and mid-summer flowering (Oriental lilies). Blooms from ALL species are removed after they're spent.
WHY should one "water in thoroughly" after planting fall bulbs? Does the water wake up these bulbs temporarily, before they resume dormancy for the winter?? What would happen if one DIDN'T water at planting??
WHY should one apply slow-release fertilizer in the soil when planting fall bulbs?? This just does not seem to make sense?!?! The bulbs are dormant and will be dormant for over the next four months (one month MORE than the fertilizer says it will last).
WHY should one apply slow-release fertilizer in the spring and fall for already-planted fall-planted bulbs? I can see why fertilize in the spring, as all the bulbs need the extra nutrients to bloom magnificiently. . . .but I don't get why wait until fall? It seems more logical to provide extra nutrients immediately after the blooms are spent, when all is being store in the bulb for NEXT year's display.
Some bulb growing practices: Why????
WHY should one "water in thoroughly" after planting fall bulbs?
This will help settle the soil in the planting bed plus provide needed moisture for the bulbs to start rooting. Fall planted bulbs must root before cold weather. Avoid over-watering at planting time since this can result in bulb rot.
WHY should one apply slow-release fertilizer in the soil when planting fall bulbs??
WHY should one apply slow-release fertilizer in the spring and fall for already-planted fall-planted bulbs?
Both spring and summer bulbs need phosphorous to encourage root development. Keep in mind that phosphorous moves very little once applied to the soil. Some bulbs are planted 6 to 8 inches deep. The phosphorus needs to be mixed in the soil below where the bulbs will be located so it can be utilized by the bulb roots. Mix bonemeal or superphosphate with the soil in the lower part of the planting bed as it is being prepared.
If bulbs are going to be maintained in a planting bed more than one year, it is important to supply additional fertilizer. Spring flowering bulbs should have mixed into the soil in the fall five tablespoons of 10-10-10 soluble fertilizer (or equivalent bulb fertilizer) plus two cups of bonemeal per ten square foot area. As soon as the shoots break through the ground in the spring, repeat the above soluble fertilizer application. Do not fertilize spring flowering bulbs after they have started flowering. This tends to encourage the development of bulb rot and sometimes shortens the life of the flowers.
Summer and fall flowering bulbs should be fertilized monthly from shoot emergence until the plants reach full flower. Apply seven tablespoons of 10-10-10 soluble fertilizer (or equivalent bulb fertilizer) split over two or three applications over a ten square foot area.
The optimum pH range for bulbs is 6 to 7. A soil test of the planting area is necessary to determine if lime needs to be applied to adjust the soil pH. If needed, limestone should be worked into the soil. For good bud development, work bonemeal into the soil at planting.
In addition to the excellent advice given above, I wanted to mention that spring flowering bulbs are dormant during the summer, but break dormancy in fall with the onset of cooler temperatures. The roots are active during fall and winter, which is why it's the recommended time to fertilize.
As you become a seasoned gardener, you're likely to experiment beyond the perimeters of recommended gardening practices, and will often find plants will thrive regardless. I have gotten away from fertilizing as heavily or as frequently as many sources suggest, but that is after years of building up the soil that was rich to start with, with compost. A soil test will also tell what nutrients your soil may be lacking, and help decide what fertilizer to use and how much.