When to Plant Sweet Alyssum in Idaho

Growing Sweet Alyssum in Idaho: Complete Guide

Sweet Alyssum (Lobularia maritima) is a crop that grows best when sown directly in the garden. Depending on your zone, the right time to direct sow in Idaho falls between March 8, 2027 (Zone 7b) and April 17, 2027 (Zone 4a), once soil temperatures are consistently warm enough for germination.

Because Idaho stretches across 8 USDA hardiness zones (4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b), planting windows can shift by as much as six to eight weeks from one end of the state to the other. Gardeners in the warmer southern zones can start earlier, while those in cooler northern zones should wait until the zone table above shows their last frost has passed.

With 45 days to maturity, Sweet Alyssum fits comfortably within Idaho's growing season in most zones. In the warmest parts of the state, a second planting later in the season may be possible.

Sweet Alyssum requires full sun to partial shade and moderate (1 inch/week) moisture. Mountain-state gardens contend with short seasons and intense UV at elevation — cold nights can persist well into June at higher altitudes.

For the most precise planting dates tailored to your exact location, enter your ZIP code on our planting calendar or use the zone table above to find the schedule for your area of Idaho.