I planted hyacinth bulbs but the flowers come up very short. Do I have the bulbs planted too deep?
Although it sounds logical that a bulb planted too deeply will have a short stem, in our Toronto climate Hyacinth bulbs prefer a deeper hole, at 6 to 8 inches deep, and some mulch on top for winter protection.
Hyacinths, or Hyacinthus orientalis, do have shorter stems than many other bulbs, but if you have noticed that your flowers are particularly short, it is more likely to be caused by a reduced prechilling period and/or a shortened dormancy.
I assume that your bulbs are planted outside. If they are in a pot inside, short stems are a more common occurrence. Light and heat exposure too early in the bulbs growth cycle may force the flower spike to bloom before it has had a chance to grow a decent stem beyond the neck of the bulb.
If your bulbs were planted outside, they may have been planted a bit late in the fall- limiting the root growing period before the ground froze. During the cool months of fall, but before the bulb becomes dormant, the roots need time to grow, to anchor the bulb into the soil and produce a hormone called Gibberellin. This hormone is released within the bulb in spring to stimulate plant growth- including stem elongation. Your bulbs prefer 16-18 weeks of cold and any interruptions to this by fluctuations in temperature or a shortened planting period can affect stem length.
If your bulbs were planted late, they should be better next year. If they were interrupted by unseasonal weather, a top up with organic mulch in the fall could help to insulate them from unpredictable weather next winter.