To propagate Grape Hyacinth, the most common method is to divide the bulb clumps by digging them up when they are dormant in late summer or early fall, gently separating the smaller “offset” bulbs from the main bulb, and replanting them in a new location; you can also propagate them by collecting seeds and sowing them in the spring, though this takes longer to flower than dividing bulbs.
Key points about propagating Grape Hyacinth:
Division is preferred: This is the easiest and fastest way to propagate grape hyacinths, as they naturally produce smaller bulbs called offsets around the main bulb.
When to divide: Best done when the plant is dormant in late summer or early fall, after the foliage has died back.
How to divide: Dig up the entire clump of bulbs.
Gently shake off excess soil. Separate the smaller offset bulbs from the larger mother bulb. Discard any damaged or diseased bulbs. Replant the separated bulbs in new locations at the same depth.
Propagating from seeds: Collect seeds from the spent flower heads after they have dried.
Sow seeds in a prepared seed bed in the fall. Note that seedlings may take a few years to bloom.