The grape hyacinth (Muscari armeniacum) propagates its thumb-sized clusters of fragrant blue blossoms through bulbs, which send out offsets to create a bulb clump. These directions will help ensure successful transplanting of your grape hyacinths.
Step 1: Find the Best Time to Transplant
Transplant in the late summer, after flowering but while new leaves are still sprouting from the stems.
Step 2: Choose the New Location
The new location can be sunny or in partial shade. Choose an area that is level with its surroundings or at a higher slope. Check that the soil has little clay and is well-drained. Add sand or gravel if the soil seems too moist.
Step 3: Dig Up the Clump
When digging bulbs, use a garden fork or pointed spade to make a shallow trench in the soil around the entire clump. Loosen the soil around the clump so that new small bulbs do not break off. Crumble away as much soil as you can to see the growth on each bulb.
Step 4: Select the Largest Bulbs
Choose the largest and healthiest bulbs for transplanting. Some may have their own small offshoot bulbs attached. Retain these so the new bulbs can form their own clumps. Pull very gently to separate each clump. The new offsets that are ready to be on their own will break away easily. Discard any withered bulbs in your compost, as well as any tiny offshoots that have not formed any roots.
Step 5: Prepare the New Location
At the transplant location, dig a large hole 8 to 12 inches wide so the new root systems can spread out. It should be shallow, just 3 inches deep. Put in bulb fertilizer or any root-stimulating mix at the bottom of the hole. Cover it with a shallow layer of dirt to prevent direct contact with the new roots. Set 4 to 6 bulbs in this hole, fill with dirt and pack it down. Water right away.
The new planting should send up some leaves in early fall. These will stay green all winter, as the grape hyacinth is remarkably winter-hardy, able to tolerate temperatures as low as 0 degrees Fahrenheit. The plant will bloom in the early spring, by the end of April.
Grape hyacinths will thrive in an indoor container in full sun. Choose large bulbs that show visible offset bulbs for indoor transplanting. Use a container 12 to 18 inches wide, and dig a shallow hole 3 inches deep.
Add either bulb or root fertilizer and potting soil to protect the bulbs. Place 3 or 4 bulbs in the hole, fill with potting soil to the surface and tamp down gently. Water it right away. Let soil dry between waterings. The bulbs will send up some leaves, and then will bloom in spring.
Mistakes to Avoid
Do not add any more fertilizer to your transplantings. This will encourage leaf growth instead of flower formation.