Complete Guide to Growing Allium: When, What, and Where to Plant

The When What And Where Of Allium

When it blooms: May (some species may bloom in summer)

What it means: Ornamental onion, a member of the lily family; it stands for unity, humility and patience

When to plant it: Fall

Where to plant it: Sun/partial shade

How to Grow Allium According To W.S. Warmenhoven 

Warmenhoven, a specialist in Holland in growing allium and amaryllis, shows its prize cultivars at RHS Chelsea and other flower shows. Here is their advice:

Unpack the allium bulbs immediately and lay them on a paper bag.

Keep the bulbs until September to November in a dry, well ventilated place and let them breath.

Don’t plant the bulbs in heavy clay soil. If you do so, lighten the clay with a mixture of sand or grit and make sure it’s not going to be a wet spot.

Allium do not do well planted in pots. If you do so, water your bulbs frequently directly after planting and throughout the whole winter, because in pots they can dry out easily.

Well drained soil is the best. They need water in the autumn to make a good root system to soak up water in the spring to produce their flowers. Make sure you don’t plant the bulbs in a very dry spot.

After planting put some bone meal on top. Planting depth is two and a half times the size of the bulb. If it’s a windy place, plant the bulbs a bit deeper.

If you let the flowers make seed heads at the end of the flowering season, they will not easy flower a second time. So, cut off the flowers. Do not let them go to seed.

After three years you can dig up the bulbs about 3 weeks after you cut off the flowers. Store and dry the bulbs until the autumn. Again, store them in a dry, well ventilated place.

Take off the small bulbs and plant the large bulbs in new places.

Four of Warmenhoven’s Newest Allium

They are sold out for this year, but there is always next year:

Purple Sensation, which flowers from May – June; it will reach 27 inches tall

Scorodoprasum Art, and unusual ornamental allium that flowers in July and will grow 43 inches tall:

Mount Everest, which lowers in May and June and grows 47 inches tall:

Silver Spring, flowers in May and grows 31 inches tall:

Remember to cut flowers before they go to see if you want to see allium bloom the following year.