Ask Annie- May Perennial Garden Checklist
Posted by Annie Algren on May 4th 2026
Welcome to May, the official start of the growing season! It’s time to stop apologizing for winter and start making promises to the plants that knew better than to give up. Keep an eye on the nightly temperatures, as our average last frost date is May 15th.
May Perennial Garden Checklist
Welcome to May, the official start of the growing season! It’s time to stop apologizing for winter and start making promises to the plants that knew better than to give up. Keep an eye on the nightly temperatures, as our average last frost date is May 15th. The frost is mostly gone, but keep your frost cloths handy just in case! Here is your May Perennial Garden Checklist:
Zone 4a: Proceed with caution; cold snaps can still occur
Zone 4b: Most perennial tasks are safe by mid-May
Zone 5a: Earlier planting is possible with frost awareness
Clean-up & Garden Prep
- Remove remaining dead stems, leaf litter, and last year’s mushy growth
Planting, Dividing & Transplanting
- Plant container-grown perennials! Aim for 40 to 50°F soil temps, or once the ground is workable.
- Continue transplanting and dividing summer & fall-blooming perennials
Mulch & Soil Care
- Apply 2-3 inches of mulch around your plants once soil has warmed, but be sure to keep it away from plant crowns to prevent rot and disease. Think of it as a donut of mulch around the plant, not a mounded volcano!
Watering & Fertilizer
- Water newly planted perennials regularly, but avoid shallow frequent watering
- Check soil moisture before watering- spring rain counts!
- Add a plant starter fertilizer like Bio Tone to newly planted perennials
- Apply slow-release fertilizer like Plant Tone to existing perennials
Staking & Support
- Stake or use cages around floppy perennials early like peonies, delphinium, phlox. Future you will thank you!
Pollinators & Pests
- Watch for slugs and cutworms. Check out this blog on tips and tricks to manage common perennial pests.
- Avoid pesticides as bees and other pollinators are just waking up for the season!
- Accept that some things will get eaten by those pesky deer and rabbits - this is nature after all.
- Identify weeds while they’re small and easily plucked!
Planning and Maintenance
- Note winter losses or slow starters
- Identify gaps in bloom or coverage- check out our guide to continuous blooms
- Plan a new garden space! Check out our handy garden plans here!
And remember, gardening is never about perfection, it’s about curiosity, patience, and perserverance! I’m cheering you on as you try new things, learn from the missteps, and celebrate each little success. Until our next chat, happy gardening and keep growing!
-Annie
Have a perennial issue, mystery, or design dilemma? Annie can help!
Always approachable and happy to help!