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.
CURRENT VARIETIES AND SOURCES
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.
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
SEED STARTING
- 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.
GROWING CONDITIONS
- 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