The weather is getting warmer and the plants are getting bigger and better this month. Here are some May gardening tips and to-dos for your Pacific Northwest garden.
The April showers that were supposed to bring the May flowers were more like hail and heavy rainstorms this year. There was even some snow in some of the Seattle areas which pretty much NEVER happens.
As far as my garden, I’m seeing a lot of green plants and leaves on the trees but we are still waiting for flower blooms other than tulips.
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I’m a self-taught hobby gardener, not a Master Gardener. Everything I share with you on my blog is my personal opinion and things that worked for me along the way.
May Gardening To-Dos
My “gardening by month” tips for May are based on hardiness zone 8b, and my average last frost date is April 18th. If you live in a different hardiness zone, make sure to confirm the frost dates in your area, and plan accordingly.
Garden Planting in the Month of May
PREPARING SOIL
It all starts with the soil, am I right?
Hopefully, you’ve already prepared your garden bed soil. If not, you can see more by CLICKING HERE.
Mulching or spreading compost can help prevent weeds, keep the soil cooler, and require less water for plants.
HARDENING OFF PLANTS
If you have started annuals from seed, be sure to start hardening them off this month if you haven’t already done so. CLICK HERE to read more about this process of acclimating your plants.
Once your seedlings are hardened off, you can transplant them into the garden beds.
TRANSPLANTING SEEDLINGS
If at all possible, transplanting should be done when it’s a calm and cloudy day. Strong sun and wind are hard on transplants and can cause a lot of stress on the plant.
PLANT DAHLIA TUBERS
Dahlia tubers can be planted in the garden or into containers now. It’s easier to add stake supports now before any growth has started.
PINCHING ANNUALS
There are certain annuals that need to be pinched back when they have reached 4-6 inches high. This helps to promote bushier growth. Some of these annuals include zinnias, petunias, salvia, sweet peas, and dahlias.
Planting Vegetables
Here are the vegetable seeds or starts you can plant in the garden for the month of May…
- peas
- beans
- sweet corn
- cucumbers
- eggplants
- melon
- pumpkins
- summer squash
- carrots
- lettuce
- potatoes
- tomatoes
- peppers
Planting Summer Annuals to Add Color to the Garden
Add color to containers and window boxes this month with annual flowers such as petunias, geraniums, lobelia, impatiens, bacopa, and begonias.
MORE ABOUT TOMATOES
You can move hardened-off tomato plants outside once the nighttime temperatures hit 50°F.
If you will be transplanting starts, smaller 4-inch plants are recommended rather than a gallon-sized plant. The smaller plants establish and transplant better than the larger ones.
For more information on tomatoes, Houzz.com has a great blog post, with great information.
Monthly Garden Maintenance
WATERING
If you have an irrigation system, check to make sure it is in good working order. Test and run each system manually, for at least five minutes, to make sure there are no leaks or repairs that may be needed.
Newly planted trees and shrubs should be watered deeply, every week or two until the autumn rain begins.
Your flowers and shrubs should get an inch of water each week.
CUT BACK SPENT FLOWERS
RHODODENDRONS AND AZALEAS
Remove any wilting seed heads from rhododendrons and azaleas once they have bloomed, in order to provide more energy to those plants.
CAMELLIAS AND ROSES
Removing spent flowers from camellias and roses will help increase the blooming time for each plant.
SPRING BULBS
Remove spent flowers from spring bulbs, such as tulips and daffodils. This will help preserve the energy for next year’s bloom. Cut each finished flower stalk at the base, but do not cut down the foliage.
The plant will naturally die back and will build food reserves to support next year’s blooms. Plant hardy annuals in areas where spring bulbs will die back. Daffodils may be divided and moved when finished blooming.
PRUNE FLOWERING SHRUBS AND VINES
Prune spring-flowering shrubs and vines after they have finished blooming and the flowers have faded. Make sure you do this immediately after flowering, so you’re not cutting into next year’s blossoms.
FERTILIZING AND FEEDING
- Lilacs – feed with 10-10-10 fertilizer after blooming.
- Roses – feed after their first bloom, then repeat feeding every 4-6 weeks. Try a complete fertilizer like a 10-10-10 granular or liquid soluble.
- Fertilize annuals, fruit trees, fuchsias, perennials, and shrubs.
- Spring-flowering shrubs like azaleas, camellias, and rhododendrons – feed with an acid-based fertilizer as soon as they have finished flowering.
- Hydrangeas – work lime in soil for the color pink, and Aluminum Sulfate for blue blooms.
WEED AND PEST CONTROL
WEED MAINTENANCE
Try to keep up with the weeds while they’re small so they’re easier to pull. You won’t have as many weeds to pull next year if you get them before they go to seed.
Pull weeds after heavy rains, and they’ll pull up easier from the soil than when the ground is dry.
PEST CONTROL
Use either a strong stream of water or use safer soap products, if you see aphids in your garden.
Slugs are in full force this time of year. Plants that are most susceptible to slugs, such as marigolds, hostas, dahlias, and zinnias, can all benefit from slug bait. I use Sluggo in my garden, which is pet and wildlife safe. However, there are more natural alternatives available as well.
Hopefully, I have given you some tips you can use in the garden for the month of May. I hope that the weather is warming up for you and you are able to take advantage of the great outdoors!
Please leave a comment below. I’d love to hear from you.
Until next time,
Happy May!
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Thank you for this post! My question is in regards to Dahlia’s. I am fairly new to the PNW and to the gardening here. I had planted Dahlias last year and cut them back when it was time. I read that it was not necessary to dig out the tubers in zone 8B, but to cover them with a winter barrier. In April I removed that winter barrier. I am just starting to see some growth peeking thru the ground. You mentioned in the article to cut back after about 4” of growth to promote fuller plants. I want to make sure that is what I should do even on tubers that were left in the ground? I hope this makes sense??
It makes perfect sense Leanne. We are so lucky to be able to leave our dahlia tubers in the ground through the winter. I do dig them up in April and look for any rotted tubers and cut them off from the rest of the clump. I also try to cut off the mother tuber. You can read my dahlia blog post about this. I think you’re fine not doing this after the second year but I would definitely think about it for next April. You should still pinch back the center of your dahlias when they get knee-high. Please feel free to let me know if you have more questions after reading the blog post.
https://shiplapandshells.com/all-youve-ever-wanted-to-know-about-dahlias/
https://shiplapandshells.com/how-to-divide-dahlia-tubers-in-the-spring/
Once again I’m in awe of your garden and you are so lucky to be planting already. We have had a drier spring so it’s possible I could try and plant early but you never know here in Colorado if the snow will creep in one more time.
The minute you plant something it will definitely snow Chas. Better safe than sorry for sure.
Kim,
Great post!! Your yard and garden is simply spectacular!! Thanks so much for taking the time to stop by and by leaving a kind comment to let me know that your did!! Stay safe, healthy and happy!!
Hugs,
Debbie
Thank you for the kind words Debbie! I love visiting your blog! Wishing you health and happiness as well my friend!