Growing Spinach: A Complete Profile
By Growing Home Greens Team · July 18, 2026
Spinach is one of the fastest, most cold-tolerant greens you can grow, direct-seeded a full month before your last frost, but it’s also quick to bolt once the weather warms, so the growing window is short and worth planning around rather than fighting.
Sowing it a month before your last frost
Sow seed directly outdoors as early as four weeks before your last frost; spinach germinates fine in cool soil that would rot most other seeds. At 40 days to maturity and a dense nine plants per square foot, it’s one of the fastest turnovers in the garden. Plan on succession sowing every couple of weeks if you want a steady harvest instead of one big flush.
Bolting and mildew, the two things that end a planting
Bolting (sending up a central flower stalk and turning bitter) is almost always a heat and daylength issue, not a care mistake; once temperatures push into the 75-80°F range, spinach is on borrowed time regardless of watering. Downy mildew shows up as yellow patches on top of the leaf with fuzzy gray growth underneath, especially in damp, humid stretches; resistant varieties help more than any spray at that point.
A fast crop that clears out before summer
Radish is a documented companion, maturing quickly alongside spinach without competing for space. See the full companion guide for spinach. Its short season and dense spacing make it a good candidate in the Garden Designer for filling a bed early and clearing out before a slower summer crop needs the room.
Companion planting guide for Spinach · Find your planting dates
Typically viable in USDA zones 2-10. Not sure your zone? Look it up by ZIP code.
Mature height: 0.5-1 ft
Method: Direct sow: Direct-sow outside. It doesn't transplant well, or doesn't need the extra time indoors.
When to plant spinach, by zone
Every zone spinach 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 | Harvest |
|---|---|---|---|
| 2a & 2bSpring window | Not usually | Apr 22–Apr 29 | Jun 1–Jun 8 |
| Fall window | Not usually | Jul 9–Jul 23 | Aug 18–Sep 1 |
| 3a & 3bSpring window | Not usually | May 2–May 9 | Jun 11–Jun 18 |
| Fall window | Not usually | Jul 13–Jul 27 | Aug 22–Sep 5 |
| 4a & 4bSpring window | Not usually | Apr 17–Apr 24 | May 27–Jun 3 |
| Fall window | Not usually | Jul 28–Aug 11 | Sep 6–Sep 20 |
| 5a & 5bSpring window | Not usually | Apr 12–Apr 19 | May 22–May 29 |
| Fall window | Not usually | Aug 12–Aug 26 | Sep 21–Oct 5 |
| 6a & 6bSpring window | Not usually | Mar 28–Apr 4 | May 7–May 14 |
| Fall window | Not usually | Aug 22–Sep 5 | Oct 1–Oct 15 |
| 7a & 7bSpring window | Not usually | Mar 13–Mar 20 | Apr 22–Apr 29 |
| Fall window | Not usually | Sep 1–Sep 15 | Oct 11–Oct 25 |
| 8a & 8bSpring window | Not usually | Feb 25–Mar 4 | Apr 6–Apr 13 |
| Fall window | Not usually | Sep 17–Oct 1 | Oct 27–Nov 10 |
| 9a & 9bSpring window | Not usually | Jan 18–Jan 25 | Feb 27–Mar 6 |
| Fall window | Not usually | Oct 12–Oct 26 | Nov 21–Dec 5 |
| 10a & 10bFall window | Aug–Dec | Sep–Jan | ~40 days after transplanting |
Harvest dates are about 40 days after the sow or plant-out date.
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 Spinach plants fit per square foot?
Spacing: 9 per square foot (square-foot-gardening spacing). Mature height: 0.5-1 ft.
Soil & water: pH 6-6.5. Needs well-drained soil. Amend with lime if soil pH falls below 6.
Good companions for spinach
- Radish: Radish breaks up soil and matures quickly alongside spinach.
Full companion guide, including what to keep away from spinach →
Varieties worth considering
- Space (F1): Rated by the seed company with high resistance across a wide range of downy mildew races (1-3, 5, 6, 8, 9, 11, 12, 14, 16, 19), a smooth-leaf, all-season type worth considering where downy mildew has been a recurring problem. (source) Buy seeds: Botanical Interests · Burpee · High Mowing Organic Seeds
- Bloomsdale Long Standing: An open-pollinated heirloom, savoyed rather than smooth-leaf, that Cornell's disease-resistance factsheet lists as resistant to Downy Mildew races 1-12, 14 and 15. The one to grow if you want to save your own seed, which the hybrid Space above doesn't let you do reliably. (source) Buy seeds: True Leaf Market · Burpee
- Hammerhead (F1): A full-savoy type Johnny's rates at about 27 days, resistant to downy mildew races 1-12, 14-16 and 19 plus intermediate white rust resistance. Bred specifically for early spring, fall and winter sowing since it bolts quickly once the weather warms, the opposite job to a slow-bolt summer pick. (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 spinach seeds
Botanical Interests · Burpee · High Mowing Organic Seeds (each supplier's spinach seeds)
The varieties we recommend above each have their own buy links, for the suppliers that sell that exact variety.
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See it growing
Search YouTube for "growing spinach" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
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Growing Spinach: A fast, cold-loving green that bolts the moment it gets warm. Timing matters more than technique.
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