What to Plant in May
Denver, CO · Zone 5b
Last frost: May 5
Frost-free days: 154
Frost may still be possible early in the month. Harden off your indoor seedlings and transplant after your last frost date. Direct sow beans, squash, and cucumbers once the soil warms.
May at a Glance
Indoor
Transplant
Direct Sow
1
5
10
15
20
25
Chives
Cilantro
Dill
Mint
Oregano
Parsley
Sage
Thyme
Artichoke
Beans (Bush)
Beet
Broccoli
Brussels Sprouts
Cabbage
Carrot
Cauliflower
Celery
Kale
Leek
Lettuce
Onion
Peas
Potato
Radish
Spinach
Squash
Strawberry
Swiss Chard
Turnip
Zucchini
Start Indoors 11
Start these seeds indoors under grow lights or on a sunny windowsill.
Parsley
Feb 15 – May 8
4 per sq ft
70–90 days
Broccoli
Mar 1 – May 23
1 per sq ft
60–100 days
Cabbage
Mar 1 – May 23
1 per sq ft
70–100 days
Cauliflower
Mar 1 – May 23
1 per sq ft
55–100 days
Kale
Mar 9 – Jun 23
1 per sq ft
50–65 days
Strawberry
Mar 9 – May 8
4 per sq ft
60–90 days
Lettuce
Mar 24 – May 16
4 per sq ft
45–60 days
Spinach
Mar 24 – May 8
9 per sq ft
35–50 days
Swiss Chard
Mar 24 – Jul 16
4 per sq ft
50–60 days
Squash
May 9 – Jun 8
1 per sq ft
45–65 days
Zucchini
May 9 – Jun 8
1 per sq ft
45–60 days
Transplant 19
Move these seedlings from indoors to your garden beds.
Chives
Apr 24 – Jun 23
9 per sq ft
60–90 days
Mint
Apr 24 – Jun 23
4 per sq ft
60–90 days
Parsley
Apr 24 – Jul 16
4 per sq ft
70–90 days
Broccoli
Apr 24 – Jul 16
1 per sq ft
60–100 days
Brussels Sprouts
Apr 24 – Jul 16
1 per sq ft
80–110 days
Cabbage
Apr 24 – Jul 16
1 per sq ft
70–100 days
Cauliflower
Apr 24 – Jul 16
1 per sq ft
55–100 days
Kale
Apr 24 – Aug 8
1 per sq ft
50–65 days
Leek
Apr 24 – Jun 8
4 per sq ft
90–150 days
Lettuce
Apr 24 – Jun 15
4 per sq ft
45–60 days
Onion
Apr 24 – Jun 8
9 per sq ft
100–120 days
Spinach
Apr 24 – Jun 8
9 per sq ft
35–50 days
Strawberry
Apr 24 – Jun 23
4 per sq ft
60–90 days
Swiss Chard
Apr 24 – Aug 16
4 per sq ft
50–60 days
Oregano
May 1 – Jun 15
1 per sq ft
60–90 days
Sage
May 1–31
1 per sq ft
75–90 days
Thyme
May 1 – Jun 8
4 per sq ft
70–90 days
Artichoke
May 1 – Jun 15
1 per sq ft
85–100 days
Celery
May 1 – Jul 16
4 per sq ft
80–120 days
Direct Sow 9
Plant these seeds directly into the soil outdoors.
Plant now
Cilantro
Mar 17 – Jun 15
9 per sq ft
30–45 days
Turnip
Mar 17 – Sep 23
9 per sq ft
30–60 days
Beet
Mar 24 – Sep 8
9 per sq ft
50–70 days
Carrot
Mar 24 – Jul 31
16 per sq ft
70–80 days
Peas
Mar 24 – Jun 30
8 per sq ft
55–70 days
Radish
Mar 24 – Jun 15
16 per sq ft
22–30 days
Potato
Apr 24 – Jul 8
1 per sq ft
70–150 days
Later this month
Dill
May 17 – Jul 31
4 per sq ft
40–60 days
Beans (Bush)
May 17 – Jun 30
9 per sq ft
50–60 days
May Gardening Tips
- Start Squash, Zucchini, Lettuce indoors now to give them a head start before transplanting outside.
- Lettuce, Broccoli, Cabbage can be transplanted outside this month. Harden off seedlings over 5–7 days before planting out.
- Direct sow Beans (Bush), Carrot, Peas straight into the garden — no transplanting needed.
- Mulch around transplants with 2–3 inches of straw or shredded leaves to retain moisture and suppress weeds.
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