Marigold in Zone 3a & 3b
Tagetes
Yes, marigold grows in zones 3a and 3b. Start seeds indoors Apr 18–Apr 25 and plant out Jun 6–Jun 13.
When to plant marigold in zone 3b
Zones 3a and 3b share the same average frost dates, so this page covers both.
Method: Either: Start indoors for an earlier harvest, or direct-sow outside for less fuss. Either works.
| Start indoors | Apr 18–Apr 25 |
|---|---|
| Direct sow / transplant outside | Jun 6–Jun 13 |
| Estimated bloom | Jul 26–Aug 2 (~50 days after planting) |
Spacing: 4 per square foot (square-foot-gardening spacing). Mature height: 0.5-1 ft.
Plant alongside it in zone 3b
These go outside within two weeks of marigold in zone 3b, so one planting day can cover them.
- NasturtiumJun 6–Jun 13
- Ageratum (Flossflower)Jun 6–Jun 13
- Annual Geranium (Pelargonium)Jun 6–Jun 13
- Butterfly Weed (Asclepias)Jun 6–Jun 13
- Campanula (Bellflower)Jun 6–Jun 13
- Castor BeanJun 6–Jun 13
Marigolds earn their place in a vegetable garden on function more than looks, though the looks aren't bad either: compact mounded plants under a foot tall, covered in ruffled gold, orange, or bicolor blooms from early summer to frost. They're grown here as a companion planting tool for pest suppression, not as something you'll harvest and eat.
How marigold fits zone 3's season
Zone 3b's frost-free window runs about 98 days, from May 30 to September 5. Marigold needs about 50 days from sowing to first bloom.
Marigold planting windows in every zone
Zone 3b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Bloom |
|---|---|---|---|
| 2a & 2b | Apr 8–Apr 15 | May 27–Jun 3 | Jul 16–Jul 23 |
| 3a & 3b (your zone) | Apr 18–Apr 25 | Jun 6–Jun 13 | Jul 26–Aug 2 |
| 4a & 4b | Apr 3–Apr 10 | May 22–May 29 | Jul 11–Jul 18 |
| 5a & 5b | Mar 29–Apr 5 | May 17–May 24 | Jul 6–Jul 13 |
| 6a & 6b | Mar 14–Mar 21 | May 2–May 9 | Jun 21–Jun 28 |
| 7a & 7b | Feb 27–Mar 6 | Apr 17–Apr 24 | Jun 6–Jun 13 |
| 8a & 8b | Feb 11–Feb 18 | Apr 1–Apr 8 | May 21–May 28 |
| 9a & 9b | Jan 4–Jan 11 | Feb 22–Mar 1 | Apr 13–Apr 20 |
| 10a & 10bSpring window | Jan–Apr | Feb–May | ~50 days after transplanting |
| Fall window | Aug–Sep | Sep–Oct | ~50 days after transplanting |
| 11a & 11b | Nov 20–Nov 27 | Jan 8–Jan 15 | Feb 27–Mar 6 |
Bloom dates are about 50 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.
Good companions
- Tomato: UF/IFAS Extension confirms French marigold is effective against a wide range of root-knot nematode species: a real, documented effect, not folklore. The insect-pest-deterrent half of this claim is less well documented.
- Zucchini: An Iowa State study found marigold (alongside nasturtium) reduced squash bug and cucumber beetle damage when planted near squash, a real trap-crop/deterrent effect rather than folklore.
Where to buy marigold seeds
Botanical Interests · True Leaf Market · Burpee · High Mowing Organic Seeds (each supplier's marigold seeds)
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing marigold" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 3b calendar · Plan your beds in the Garden Designer →
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Growing Marigold in USDA zone 3b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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