Hyacinth is a hardy perennial that spreads by sprouting smaller bulbs off its main bulb. You can transplant outside once the bulbs are established, after about 3 years of growth. Follow these steps to ensure the minimum of shock and maximum of bloom in summer for your transplanted hyacinths.
Step 1: Transplant in Late Spring
You can transplant hyacinths in the fall, but it is easier to find the bulb clumps in the late spring once the flowers have bloomed and dropped off.
Step 2: Dig Deep to Get the Root Ball and Bulb Clump
Use a garden trowel or spade to dig vertically into the ground a few inches away from the main stem. Push the trowel or spade down 6 inches to avoid cutting the bulb clump or root system. Gently lean down on the handle of the trowel or spade to lever the bulb clump up to the surface. The bulb should be at the center of a clump, with several small offsets attached.
Divide up the bulb clump, and carefully extract the largest offsets. Some of these will have their own small bulbs attached. These are the best candidates for transplanting.
Step 3: Choose and Prepare the Transplant Location
Dig a hole for a mass planting about 6 inches deep. Make the hole about 15 inches in diameter. Add bulb fertilizer and cover it with garden soil.
Step 4: Transplant the Hyacinth Bulbs
Choose 3 of the bulb offsets and plant them at the bottom of the hole, 4 to 5 inches apart. Press the dirt down firmly for support. Water until soil is soaked, providing more water for the next 3 days till roots are settled. If you have sufficient space, plant more groups of hyacinths in the same manner.
Step 5: Results
Your transplanted hyacinths will need a period of cold weather in which to lie dormant before they will bloom again. Leave them alone after transplanting and monitor their growth next spring.
Step 6: Care and Maintenance
Water sparingly, but provide more in the dry period of late summer. Deadhead the blooms grown from bulbs to retain nourishment. If you have purchased self-sowing hyacinths, leave the flowers on till they drop off of their own accord.
Guard your hyacinth bulbs from digging pests and rodents by fencing them off. Alternatively, if rodents are chewing on the bulbs, dig them up again carefully and install hardware cloth (a stiff fabric with wire mesh embedded in it) to create a barrier that will safeguard the roots.
In cases where the growth is weak or slow, check for symptoms of insect or disease infestation. Destroy diseased bulbs and dig out old soil. Then add fresh topsoil with some sand and fertilize. Guard against overwatering as well, as this will encourage the growth of fungus.
Hyacinth bulbs are hardy in winter down to 0 degrees Fahrenheit, so there is no need to cover them or bring them in for the winter.