Only Put the Bulb in the Planting Hole
To avoid even the slightest possibility of root burn, never put anything in the bottom of each planting hole under the basal plate of the bulb. In sharp contrast to the horticultural practice of years gone by, fertilizer should never be mixed into planting holes. There is absolutely no incremental benefit. It only risks cauterizing the basal plate and destroying the bulb's ability to generate root growth. The soil must be neutral pH. You may refer to our section on Soil Good for Flower Bulbs.
Do not amend individual planting holes with anything, and never top dress flower bulb beds with soil amendments. Never use mint mulch, horse manure, chicken droppings, mushroom compost, other "hot" manure, garden compost, household compost or commercial soil amendments. These soil additives may create acidic or alkaline pH levels that prevent or retard root growth and stunt plant development. They can actually rot the bulbs themselves. Garden and household compost often fail to decompose fully due to insufficient heat generation, and can be a breeding ground for damaging fungus and weeds.