How to Propagate Alpine Sea Holly (Eryngium alpinum)

This guide is meant to teach you how to propagate Alpine Sea Holly (Eryngium alpinum) and hopefully make it easier for you to sell them at your own nursery.

Hardiness Zone: 2 – 10

Soil Type: Well-drained chalk, loam, sand. Prefers dry, moderately fertile soils.

Water: Below Average, Water during long periods of drought.

Exposure: Full Sun

Alpine Sea Holly (Eryngium alpinum) is a perennial shrub hardy up to zone 2. Alpine sea holly flowers are quite something, their thistle-like appearance along with the blue-tinted flowers make them a striking addition to any garden.

Alpine sea holly flower blooms last a long time, they start during summer and sometimes last into fall.

If planted in the right spot they are quite a carefree plant with very little maintenance.

Widlife Value

Alpine sea holly flowers attract pollinators like bees and butterflies.

Deer and rabbits will typically refrain from eating alpine sea holly.

Best Way to Propagate Alpine Sea Holly

Method: Root Cuttings

A good way to propagate alpine sea holly is by taking root cuttings. The thing is, they like to grow one big taproot, which won’t make digging out parent plants easy.

• First: Find a parent plant, either wild or one you’d have planted for more than a year. Best time is late summer.
• Next: Cut away a clump of root, no more than 33% of total root mass. You can get 3-4 good clumps per plant if you’re careful.
• Finally: Replant the parent plant back where it was, then plant the root cuttings individually in a mix of perlite and peat moss.

Tip: The cut end should be upwards, and entirely below the surface of the soil but not too deep.

Place the root cuttings in a sheltered place like a garage or shed over winter, by spring new roots and shoots will come up. Water occasionally and monitor the cuttings for mold.

Method: Sowing

You can also grow alpine sea holly from seed, but it will be much slower.

Like nearly all zone 2 perennial shrubs, sea holly seeds need to go through stratification. Because of this, the best time to plant them is during fall outside and to let them stratify naturally.

Prepare some closed-off propagation beds that can get through winter. Fill them with a moist sterile mix like sand, perlite, or vermiculite.

Tag the area where you sow so you don’t get mixed, sow your seeds on the surface and cover with a thin layer of mix.

Leave them like this through winter, once spring comes around water them and they will sprout.

How to Prepare Alpine Sea Holly for Sale

Once your root cuttings make a strong enough stem, transplant them into pots of well-drained soil like like or silt.

Put them under full sun in your plant nursery area and keep them moist twice daily with sprayers. Once at dawn and once at the end of the day.

From there on, no need to prune, they will do just fine given the right soil and sun condition.

Need some help setting up your plant nursery? Check out our plant nursery guide.