Growing Annual Phlox: A Complete Profile
By Growing Home Greens Team · August 10, 2026
Annual phlox is a compact, fast, and easy bedding flower in unusually bright, saturated colors, worth telling apart from the taller, perennial garden phlox that shares the common name but grows and behaves quite differently.
Sowing it in the dark
Direct-sow in spring as soon as the soil is workable, or start indoors 4 to 6 weeks before your last frost. Unlike many flowers on this site, phlox seed needs darkness to germinate, not light, so cover it with about 1/8 inch of fine soil rather than leaving it exposed. Germination takes 5 to 10 days at 60-65°F. Space plants 8 to 12 inches apart.
Handle transplants gently
Phlox dislikes root disturbance more than most bedding annuals, so if starting indoors, handle the move to the garden carefully and avoid letting roots get pot-bound beforehand. It thrives in full sun with rich, moist, well-drained soil, and works as well in containers and borders as it does in a dedicated cutting row.
Cutting for a vase
Harvest fresh stems once about half the flowers on a stem have opened, which balances bloom count against the longest usable vase life.
Phlox has no well-established companion pairings, and nothing it needs to be kept away from. At 2 plants per square foot, it works well as a dense border filler or container plant in the Garden Designer.
Source: Phlox: Key Growing Information, Johnny’s Selected Seeds.
Companion planting guide for Phlox (Annual) · Find your planting dates
Typically viable in USDA zones 2-11. Not sure your zone? Look it up by ZIP code.
Mature height: 0.5-1.5 ft
Method: Either: Start indoors for an earlier harvest, or direct-sow outside for less fuss. Either works.
When to plant phlox (annual), by zone
Every zone phlox (annual) grows in. Pick your zone in the header and it will be highlighted here. Each zone links to its full page.
| Zone | Start indoors | Sow or plant out | Bloom |
|---|---|---|---|
| 2a & 2b | Apr 15–Apr 22 | May 13–May 20 | Jul 22–Jul 29 |
| 3a & 3b | Apr 25–May 2 | May 23–May 30 | Aug 1–Aug 8 |
| 4a & 4b | Apr 10–Apr 17 | May 8–May 15 | Jul 17–Jul 24 |
| 5a & 5b | Apr 5–Apr 12 | May 3–May 10 | Jul 12–Jul 19 |
| 6a & 6b | Mar 21–Mar 28 | Apr 18–Apr 25 | Jun 27–Jul 4 |
| 7a & 7b | Mar 6–Mar 13 | Apr 3–Apr 10 | Jun 12–Jun 19 |
| 8a & 8b | Feb 18–Feb 25 | Mar 18–Mar 25 | May 27–Jun 3 |
| 9a & 9b | Jan 11–Jan 18 | Feb 8–Feb 15 | Apr 19–Apr 26 |
| 10a & 10b | Dec 26–Jan 2 | Jan 23–Jan 30 | Apr 3–Apr 10 |
| 11a & 11b | Nov 27–Dec 4 | Dec 25–Jan 1 | Mar 5–Mar 12 |
Bloom dates are about 70 days after the sow or plant-out date, not after starting seeds indoors.
Zone 2 sows before zone 3 here, which looks wrong and is not. USDA zones rank winter cold, not season length, and zone 2 is mostly interior Alaska, where hard winters come with warm summers. More on what a zone measures.
See exact start-indoors, direct-sow, and harvest dates for your zone →
How many Phlox (Annual) plants fit per square foot?
Spacing: 2 per square foot (square-foot-gardening spacing). Mature height: 0.5-1.5 ft.
Varieties worth considering
- Straight-species annual phlox (Phlox drummondii): Johnny's Selected Seeds sells this species in a range of named color mixes and single strains; the growing requirements are consistent across them, so the species itself covers what matters for care. (source)
- 'Cherry Caramel' annual phlox (best for: cut-flower stem length): Johnny's Selected Seeds describes this as having long stems and an antique look, a perfect cut flower and border plant, bred longer-stemmed than a standard bedding mix. (source) Buy seeds: Botanical Interests
- 'Art Shades Mix' annual phlox (best for: fast-growing bouquet color): Johnny's Selected Seeds lists this as a fast-growing accent flower for bouquets and borders, a mixed-color alternative to the single-tone Cherry Caramel above. (source)
Why each variety is listed comes from the source shown next to it. We haven't grown these ourselves yet, so treat this as a research-backed starting point, not a personal endorsement. The buy links are separate from those sources: they go to seed suppliers that sell that exact variety, and we may earn a commission on some of them.
Where to buy phlox seeds
Botanical Interests · True Leaf Market (each supplier's phlox seeds)
The varieties we recommend above each have their own buy links, for the suppliers that sell that exact variety.
As an Amazon Associate we earn from qualifying purchases. Some links on this page also go to other retailers we may earn a commission from as an affiliate, at no extra cost to you. We only recommend products with a clear consensus of positive, independent reviews, or ones we bought and use ourselves. Each item on our gear page says which.
See it growing
Search YouTube for "growing phlox (annual)" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
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Growing Phlox (Annual): An easy bedding and cut flower in saturated colors, distinct from the taller perennial garden phlox, and a plant that dislikes root disturbance more than most.
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