My Everchanging Garden

Gardening That Grows With Me

Growing Alyssum – Some Varieties Need Less Shearing

My first try with Alyssum was a McKenzie Seeds package picked up on a whim at a big box store – Carpet of Snow. I quickly fell in love, except Carpet of Snow is leggy, so needs frequent shearing if grown in a container. I’ve since switched to shorter varieties which will bloom longer without shearing or cutting back.

This is my personal growing guide. I use it to track seed sources, when to start seeds and if I should adjust growing conditions in my own greenhouse and garden. Please don’t consider this professional grower’s advice. I like the plant card information from Ball Seed Company. You can find an alyssum growing card here.


Swallowtail Garden Seeds

  • Wonderland Deep Rose – new 2024
  • Wonderland Deep Purple – new 2024
  • Clear Crystal Purple
  • Clear Crystal Lavender

I also need Wonderland Blue – I sourced this via Stokes in 2023, but they don’t have ordering set up yet. Swallowtail has on ‘too come’. I loved this colour in 2023 so hope I can find again for 2024.

Hardiness tolerates light frost so it keeps going from spring to late fall
Exposure full sun, some shade tolerance
Deer resistant yes
Bloom time & length early spring to late fall, past frost
Deadheading, care shorter varieties only needed one shearing in mid-summer and then not all pots
Water & soil conditions medium
Height I prefer shorter varieties, see my note on Carpet of Snow below
Spacing 12-14 inches

My notes:

In 2023 I tried several shorter varieties – both Clear Crystal and Wonderland were only 6 inches tall or so. They bloomed nonstop and worked extremely well in my annual planters. I put what seed of Carpet of Snow I had left in the vegetable garden for the pollinators.

I’m sticking with Alyssum over Bacopa as a small flowered spiller in containers. Bacopa looks great when it’s blooming but often stops blooming during mid-summer here.

container annuals in the seating area

I used Alyssum as a stand-alone in small 8-inch containers and as a spiller in larger containers. This is Clear Crystal Lavender in the left planter.

For 2024:

  • trying more Wonderland colours
  • test out how early you can transplant in the spring since cold-tolerant


  • 8 weeks before frost is Mar 25
  • Sow thinly in 6-cell pots. You can multi-sow and transplant but the seedlings are very small and you get a lot of seeds per package so this is easier. I cut out the smaller seedlings and leave 3-4 per cell.
  • Press into soil. Do not cover. Seed needs light to germinate. Barely cover with vermiculite if pelleted.
  • Does not need heat mat to germinate. Will germinate 55-70°F / 13-21°C in 2 to 10 days.


  • bottom water
  • cool season crop can grow with little to no heat (nights can be as cool at 55-60°F or 13-16°C) so place in cooler parts of the greenhouse
  • move seedlings outside early to harden off and bring in on very cold nights

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