March Gardening Tips and To-Dos for the Pacific Northwest Region

Are you starting to see signs that your garden is waking up from its winter slumber? I’ll share gardening tips and to-dos for March to set your Pacific Northwest garden up for success.

As the days grow longer and the weather starts warming up, spring is in the air. Here in the Pacific Northwest, March is a great time to get your garden in shape for the upcoming growing season.

The spring bulbs are finally starting to pop out of the ground in the garden as spring approaches. Hellebores and heather plants are blooming, and our camellias will start blooming soon.

So many changes are starting to happen to our Pacific Northwest garden in March. It’s still one of the colder months, with winter temperatures still lurking in the 30s, but Daylight Savings Time is happening this month, and we can start spending more and more time outdoors.

This is also my busiest month of the year in the greenhouse, with new seeds to sow. I’ll be sowing the rest of my cut flowers in early March.

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Here are some Pacific Northwest gardening tips and things to do in March to prepare your garden for the next growing season.

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Garden Planting and Sowing Seeds in March

Vegetables to Plant in the Ground

Many cool-season crops such as broccoli, peas, Brussels sprouts, cabbage, cauliflower, kale, lettuce, onions, and shallots can be directly planted in the garden as soon as the soil temperature is consistently at or above 40°F.

Invest in a soil thermometer to make it easier for you to be sure it’s the best time to plant.

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Planting Asparagus

When planting crowns in early spring as soon as the soil can be worked, you should have asparagus to eat the following year. It can take 2-3 years to harvest if you are planting seeds.

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Sow Vegetable Seeds Indoors

Start seeds for cole crops like cabbage and broccoli indoors or directly outdoors.

Warm-season vegetable seeds should be sown indoors for basil, eggplant, peppers, tomatoes, cucumbers, and melons.

Sow seeds for peas, artichokes, strawberries, and blueberries.

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Start Planting Spring-Planted Bulbs

March is the planting season for spring-planted bulbs such as gladiolus, begonias, ranunculus, and calla lilies towards late March.

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Sow Flower Seeds Indoors

March is the ideal time to begin sowing seeds for flowers in the Puget Sound.

Summer cut flower seeds such as zinnias and cosmos should be sown indoors this month. For more tips on sowing seeds, visit my blog post, Seed Starting Basics 101.

Knowing your last frost date is essential to sow your seeds appropriately. You can find suggestions on coordinating with your frost dates on the back of your seed packets.

Flower varieties like stock and lupine do well with a succession planting plan. This is when you sow seeds every few weeks for a longer growing season. This information should be on the seed packets as well.

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Plant Annual Flowers to Bring Color to the Garden

Primroses, violas, pansies, and cornflowers are frost-resistant and cold-tolerant annual flowers. They can be planted around the garden and in containers to brighten up your March Pacific Northwest garden.

Your local nursery should be stocked up on these hardy annuals this month.

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Pruning and Cutting Back Plants in the March Garden

Cut Back Old Perennial Growth

Cut back any old growth from your perennial flowers.

Pruning encourages new growth and allows for better air circulation and light penetration.

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Finish Pruning Projects

Fruit Trees and Grapevines |

If you haven’t finished pruning your fruit trees and grapevines already, you’ll want to do so as soon as possible.

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Roses

Remove old, thin, unproductive rose canes early in the month. Cut back bush roses to 12-18 inches tall and shrub roses to 3 feet.

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Clematis

Italian and scarlet clematis should be cut back in late winter to a pair or two of buds, approximately 8-12 inches from the ground. This group is new wood and should be at eye level when they bloom in the summer.

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Evergreen Shrubs

March is a great time to prune evergreen shrubs in the Pacific Northwest garden. New growth will start soon after, and the shrub will have plenty of time to recover before summer.

Remove dead or damaged branches and thin out crowded branches.

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Ornamental Grasses

In the Pacific Northwest, ornamental grasses should be cut back or pruned in late winter or early spring. This is when the grasses are just showing signs of new growth.

Pruning helps promote air circulation, which can help reduce the soil’s moisture and decrease the risk of mold and mildew.

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*WAIT TO PRUNE SPRING-FLOWERING SHRUBS UNTIL AFTER THE BLOSSOMS FADE.

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Clean Up Your Garden

One of the first things you’ll want to do is get a head start on cleaning your garden beds.

Start by removing any dead or decaying plants.

Rake away any leaves and debris that have accumulated over the winter months.

It’s a good idea to gradually pull winter mulch from your garden beds as plants show signs of new growth. Acclimate your plants by removing the mulch over several days.

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Fertilize Plants and Bulbs

Rhododendrons, Azaleas, and Camellias | 

Choose a fertilizer designed for acid-loving plants.

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Clematis

Work the fertilizer into the soil around the base of clematis vines and water. Refresh mulch around vines.

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Bulbs

As new shoots appear, work in bulb fertilizer into the soil around plants. This feeding ensures an even better performance next year.

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Roses

Feed your roses after pruning.

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Divide Summer and Fall Blooming Perennials

Early spring is a good time of year to divide and transplant crowded and overgrown perennial clumps.

This will ensure they are healthy and produce abundant flowers next season. Summer and fall blooming perennials include:

• Shasta daisies
• Black-eyed Susans
• Asters
• Coneflowers
• Garden mums
• Day Lilies
• Phlox
• Sedum Autumn Joy

This timing gives new transplants an entire growing season to recover before facing cold winter conditions.

If the perennial blooms before mid-June, then divide in fall. If the perennial blooms after mid-June, then divide in early spring. You can see more information in my post about dividing HERE.

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Pest and Weed Control

Both preventive pest management and weed control are crucial for a healthy garden. If you let things slip through the cracks, you’ll have difficulty catching up later in the spring.

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Stay on Top of the Weeds

It only takes a little sun before the weeds in your March garden start sprouting. Keep up on weeds in garden beds before they grow out of control. Now is the time to weed your garden before weeds can flower and go to seed.

Applying a layer of mulch to your garden beds will help to suppress weeds.

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Slug Maintenance

Rain brings slugs and snails, so control them by eliminating their hiding places. Clean up leaves, and use some slug bait around your most susceptible plants.

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Apply Deer Repellent

The deer love tulips. When you start to see tulip foliage pop up out of the ground, spray a deer repellant when you have a day with no rain or wind.

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Take Preventive Measures Against Insect Pests

In the Pacific Northwest garden, preventive insect pest measures should be started in early spring, as soon as the soil is workable.

• Start by making sure your garden is clean and free of weeds and debris, which can provide a place for pests to hide.
• Inspect plants regularly for signs of insect pests, and remove any infested plants immediately.
• Encourage beneficial insects such as ladybugs, lacewings, and hoverflies, which can help to control pests.
• Plant companion plants and herbs such as garlic, mint, and marigolds to help repel pests.
• Use insecticidal soaps or horticultural oils.

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Maintain Your Garden Tools

Check your garden tools and ensure they’re in good condition.

Sharpen your pruners and hoes, and make sure your wheelbarrow has enough air in the tires.

I hope these Pacific Northwest gardening tips and things to do in March will help you prepare your garden for the next growing season.

The more you do this month, the healthier and more beautiful your garden will look this spring and summer.

I hope this gives you an idea of some gardening to-dos that need to be done here in the Pacific Northwest for March.

Send this link to anyone you know who may find this helpful.

Questions or ideas? Leave a comment below. I’d love to hear from you!

Until next time,

Happy Gardening!

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