When to Plant Sweet Alyssum in USDA Zone 9a
Sweet Alyssum (Lobularia maritima) is a low-growing cool-season annual prized for its honey-scented clusters of tiny white, pink, or purple flowers. A workhorse border plant, it tolerates light frost, self-seeds readily, and attracts beneficial insects throughout its bloom season. In warm climates it often re-blooms in fall after summer heat fades.
In Zone 9a, the average last spring frost is around February 10 and the first fall frost is around December 10, giving you a growing season of approximately 303 days.
Sweet Alyssum Planting Timeline — Zone 9a
Where Is USDA Zone 9a?
The map below highlights the states that contain Zone 9a. Click any state to see the Sweet Alyssum planting schedule for that location.
Sweet Alyssum Planting Calendar — Zone 9a
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | January 13 | Jan 13 – Jan 27 |
| Direct Sow | December 16 | Dec 16 – Jan 6 |
| Bloom | February 17 | Feb 17 – Jun 2 |
| Fall Sowing | October 1 | Oct 1 – Oct 15 |
· 6" apart · Rows 8" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Transplant Outdoors Direct Sow |
| February | Bloom |
| March | Bloom |
| April | Bloom |
| May | Bloom |
| June | Bloom |
| July | — |
| August | — |
| September | — |
| October | Fall Sowing |
| November | — |
| December | Direct Sow |
Free Zone 9a Planting Calendar PDF
Know exactly when to plant every crop in your zone. Get a printable month-by-month calendar customized for Zone 9a with start dates, transplant windows, and harvest times.
Growing Conditions
Sun
Full Sun (6-8+ hours)
💧 Water
Low — drought tolerant
Days to Maturity
45–60 days
Soil pH
6 – 7.5
Zone Temperature Range
20°F to 25°F average annual minimum
Growing Season
303 days (Zone 9a average)
Planting Specifications
| Plant Spacing | 6 inches apart |
| Row Spacing | 8 inches between rows |
Succession Planting Sweet Alyssum in Zone 9a
Sow every 5.1 weeks for continuous harvest throughout the season.
Growing Tips for Sweet Alyssum in Zone 9a
Zone 9a offers a long growing season (~303 days). You can plant Sweet Alyssum earlier and may get multiple harvests.
Surface-sow seeds — they need light to germinate. Direct-sow as soon as soil can be worked in spring; in zones 7+ also sow in fall. Thin to 6 inches apart. Shear back hard in midsummer when heat causes dormancy — plants recover and re-bloom when cool weather returns. Self-seeds prolifically; allow a few plants to set seed for a perpetual colony.
Companion Planting
Good Companions
The Gardener's Encyclopedia to Companion Planting
The pairings that make vegetables, herbs, and flowers grow better — and the ones that quietly wreck a bed.
- Proven pairings for 200+ vegetables, herbs, flowers, and fruits
- Full seed-starting + planting schedule with timing and spacing
- Bonus: square-foot gardening guide + printable seasonal planners
Saving Sweet Alyssum Seeds
Recommended for Your Garden
Reduce heat stress and sun scorch in hot climates with UV-stabilized shade cloth.
Start seeds indoors with reusable cell trays and humidity domes.
Test your soil pH, nitrogen, phosphorus, and potassium levels before planting.
Sweet Alyssum in Other Zones
Sweet Alyssum by State
- Alabama
- Alaska
- Arizona
- Arkansas
- California
- Colorado
- Connecticut
- Delaware
- Florida
- Georgia
- Hawaii
- Idaho
- Illinois
- Indiana
- Iowa
- Kansas
- Kentucky
- Louisiana
- Maine
- Maryland
- Massachusetts
- Michigan
- Minnesota
- Mississippi
- Missouri
- Montana
- Nebraska
- Nevada
- New Hampshire
- New Jersey
- New Mexico
- New York
- North Carolina
- North Dakota
- Ohio
- Oklahoma
- Oregon
- Pennsylvania
- Rhode Island
- South Carolina
- South Dakota
- Tennessee
- Texas
- Utah
- Vermont
- Virginia
- Washington
- West Virginia
- Wisconsin
- Wyoming
Frequently Asked Questions
When should I plant Sweet Alyssum in Zone 9a?
In Zone 9a, plan your Sweet Alyssum planting around the average last frost date of February 10. Direct sow outdoors around December 16. Transplant seedlings around January 13.
Can Sweet Alyssum grow in Zone 9a?
Yes, Sweet Alyssum can grow well in Zone 9a, hardy in USDA zones 3a through 11b. Zone 9a has a growing season of approximately 303 days, which is sufficient for Sweet Alyssum (45-60 days to maturity).
When can I harvest Sweet Alyssum in Zone 9a?
In Zone 9a, expect to harvest Sweet Alyssum from February 17 – June 2. Sweet Alyssum takes 45-60 days from planting to harvest.
What is the last frost date for Zone 9a?
The average last spring frost in Zone 9a is around February 10, and the first fall frost is around December 10. This gives a growing season of approximately 303 days. These are 50% probability dates — actual frost dates vary year to year.
What should I plant next to Sweet Alyssum?
Good companion plants for Sweet Alyssum include Lettuce, Broccoli, Strawberries, Tomatoes. These companions can help with pest control, pollination, and nutrient sharing.
Your Zone 9a Garden Planner — Free
A 22-page printable planner tailored to Zone 9a. Planting dates, monthly task lists, harvest log, seed inventory, and succession charts — everything you need to plan a full season.