Planting calendar
May Planting Guide for Denver, CO: Raised Beds, Containers & In-Ground
May in Denver is ideal for planting warm-season vegetables and flowers in raised beds, containers, and in-ground gardens. With frost risk mostly past, you can safely plant tomatoes, peppers, and herbs outdoors. Continue starting heat-loving crops indoors if needed for a later transplant.
Plant now (quick list)
Tomatoes, Peppers, Zucchini, Bush beans, Cucumbers, Basil, Marigolds, Lettuce (heat-tolerant varieties)
Plant now
- Tomatoes
- Peppers
- Zucchini
- Bush beans
- Cucumbers
- Basil
- Marigolds
- Lettuce (heat-tolerant varieties)
- Carrots
- Beets
Start indoors
- Eggplants
- Melons
- Pumpkins
- Winter squash
- Herbs like oregano and thyme
- Sweet potatoes slips
Avoid
- Broccoli
- Cauliflower
- Cabbage
- Brussels sprouts
- Peas
- Spinach
- Kale
Next 2 weeks
- Harden off indoor seedlings before transplanting
- Mulch raised beds to retain moisture
- Monitor for late frost warnings
- Water containers daily in warm weather
- Start succession planting of beans and cucumbers
- Pinch back herbs to encourage bushier growth
FAQs
When is the last frost date in Denver?
The average last frost date in Denver is typically in late April to early May, but it’s safest to wait until mid-May for planting frost-sensitive crops.
Can I plant tomatoes directly in the ground in May?
Yes, after the last frost risk has passed, tomatoes can be planted directly in raised beds, containers, or in-ground in Denver.
How often should I water container plants in May?
Containers usually need daily watering in May due to warmer temperatures and faster drying soil.
What vegetables should I avoid planting in May in Denver?
Cool-season crops like broccoli, cauliflower, and peas should be avoided as they may bolt or struggle in warming temperatures.
Is it necessary to harden off seedlings before transplanting?
Yes, gradually exposing indoor seedlings to outdoor conditions over 7-10 days helps reduce transplant shock.
Next steps
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