Washington’s cool maritime climate means kale planting requires attention to both spring frost dates and fall’s first chill. Knowing the best time to plant kale in washington is key to a long, productive harvest. This guide breaks down everything you need, from soil temps to variety choices, so you can grow kale like a pro.
Kale is a tough crop. It actually gets sweeter after a light frost. But if you plant too early or too late, you risk poor germination or bolting. Let’s get the timing right for your specific region in Washington.
Best Time To Plant Kale In Washington
The short answer is: early spring (March-April) for summer harvest, and mid-summer (July-August) for a fall and winter crop. But Washington is big. The coast, the Puget Sound area, and eastern Washington all have different microclimates. You need to adjust by about two weeks in each direction.
For western Washington (Seattle, Olympia, Bellingham), spring planting can start as early as mid-March if the soil is workable. For eastern Washington (Spokane, Yakima), wait until early April because the ground stays colder longer. Fall planting in the west can stretch into early September, while eastern gardeners should aim for late July or early August.
Why Timing Matters So Much
Kale seeds germinate best when soil temperatures are between 45°F and 75°F. If you plant when it’s too cold (below 40°F), seeds rot. Too hot (above 85°F), and they won’t sprout. Also, kale is a biennial. It wants to flower in its second year. But if you plant during a heat wave, it might think it’s been through winter already and bolt (go to seed) early.
Another factor: day length. Kale grows best with 12-14 hours of daylight. Washington’s long summer days (up to 16 hours) are perfect for leafy growth. But if you plant too late in fall, the shortening days slow growth way down.
Spring Planting: The First Window
Spring is the most common time to start kale. Here’s a step-by-step plan for Washington gardeners:
- Check your last frost date. For most of western WA, it’s around April 15. For eastern WA, it’s May 1-15.
- Start seeds indoors 4-6 weeks before that date. Use seed-starting mix and keep them under grow lights or in a sunny window.
- Harden off seedlings by putting them outside for a few hours each day, increasing time over a week.
- Transplant outdoors when soil temp reaches 50°F. Use a soil thermometer to be sure.
- Direct sow seeds 2-3 weeks before the last frost date. Cover with row cover if a hard freeze is predicted.
If you direct sow, plant seeds 1/2 inch deep and 12-18 inches apart. Thin seedlings to 12 inches apart once they have two sets of true leaves. Water well after planting.
Fall Planting: The Second Window
Fall-planted kale is often the best. The cool weather and frosts make leaves sweeter and less bitter. Plus, you can harvest well into winter if you protect the plants.
- Count back from your first fall frost date. For western WA, first frost is around November 1. Count back 8-10 weeks. That means plant in late August or early September.
- For eastern WA, first frost is around October 1. Count back 8-10 weeks, so plant in late July or early August.
- Direct sow seeds in the garden. Fall soil is warm, so germination is fast.
- Thin seedlings to 12 inches apart. Keep them well-watered during hot spells.
- Mulch around plants with straw or leaves to keep soil cool and moist.
Fall kale can survive light freezes (down to 20°F) without protection. For hard freezes, use row cover or a cold frame. You can harvest leaves all winter if you pick the outer leaves and leave the center growing point.
Regional Breakdown For Washington
Washington has three main growing zones. Here’s how the timing shifts:
Western Washington (Coast & Puget Sound)
- Spring planting: March 15 – April 15
- Fall planting: August 1 – September 1
- Winter harvest: With protection, through February
- Best varieties: ‘Winterbor’, ‘Red Russian’, ‘Lacinato’
Eastern Washington (Inland & High Desert)
- Spring planting: April 1 – May 1
- Fall planting: July 15 – August 15
- Winter harvest: Possible with heavy mulching and row cover
- Best varieties: ‘Siberian’, ‘White Russian’, ‘Dwarf Blue Curled’
Mountain & High Elevation Areas
- Spring planting: May 1 – June 1 (after snow melt)
- Fall planting: June 15 – July 15 (short season)
- Winter harvest: Not reliable without a heated greenhouse
- Best varieties: ‘Red Ursa’, ‘Vates’, ‘Dwarf Siberian’
Soil Preparation For Kale
Kale is a heavy feeder. It needs rich, well-draining soil with plenty of nitrogen. Here’s how to prep:
- Test your soil pH. Kale likes 6.0 to 7.5. If it’s too acidic, add lime.
- Add compost (2-3 inches) and work it into the top 6 inches of soil.
- Mix in a balanced fertilizer (10-10-10) at planting time. Or use a slow-release organic option.
- Ensure good drainage. If your soil is clay, consider raised beds.
Kale also grows well in containers. Use a pot at least 12 inches deep and wide. Fill with quality potting mix and add slow-release fertilizer.
Watering And Mulching Tips
Kale needs consistent moisture, especially during hot weather. Inconsistent watering makes leaves tough and bitter. Here’s a simple schedule:
- Water deeply once a week, more often if it’s hot or dry.
- Avoid overhead watering to prevent fungal diseases. Use drip irrigation or a soaker hose.
- Mulch with straw, grass clippings, or shredded leaves to retain moisture and keep roots cool.
In Washington, summer can be dry, especially east of the Cascades. Check soil moisture by sticking your finger 2 inches deep. If it’s dry, water.
Common Kale Problems In Washington
Even with perfect timing, issues can arise. Here are the most common ones:
- Bolting: Caused by heat or stress. Plant in cool weather and keep soil moist.
- Yellow leaves: Usually a nitrogen deficiency. Side-dress with compost or fish emulsion.
- Holes in leaves: Likely cabbage worms or flea beetles. Use row cover or spray with neem oil.
- Slow growth: Could be too cold, too hot, or not enough sun. Kale needs at least 6 hours of direct sun.
- Frost damage: Only a concern below 20°F. Cover plants with row cover or a blanket.
Harvesting Kale At The Right Time
You can start harvesting baby kale leaves about 30 days after planting. For full-sized leaves, wait 50-75 days. Here’s how to harvest:
- Pick outer leaves first, leaving the center rosette to keep growing.
- Harvest from the bottom up. Older leaves are tougher; younger ones are tender.
- Use a sharp knife or scissors to cut leaves cleanly.
- Don’t take more than one-third of the plant at once. This stresses it.
Kale tastes best after a light frost. In fall, wait until after the first frost to harvest for the sweetest flavor. You can store harvested kale in the fridge for up to a week. Wash and dry it first, then wrap in a paper towel and put in a plastic bag.
Extending The Harvest Into Winter
Washington winters are mild enough that kale can survive with minimal protection. Here are three methods:
- Row cover: Floating row cover adds 5-10°F of protection. Use it on cold nights.
- Cold frame: A simple wooden frame with a glass or plastic top. Keeps plants above freezing.
- Heavy mulch: Pile straw or leaves 6-8 inches deep around plants. This insulates the roots.
With these methods, you can harvest kale from November through February in most of Washington. In eastern Washington, you might need a heated greenhouse for the coldest months.
Best Kale Varieties For Washington
Not all kale is created equal. Some varieties handle cold better, others are more heat-tolerant. Here are top picks for Washington:
- ‘Winterbor’: Very cold-hardy. Grows well in western WA. Dark green, curly leaves.
- ‘Red Russian’: Tolerates both heat and cold. Flat, fringed leaves with purple stems.
- ‘Lacinato’ (Dinosaur Kale): Italian heirloom. Great for fall planting. Blue-green, bumpy leaves.
- ‘Siberian’: Extremely cold-hardy. Best for eastern WA winters. Large, tender leaves.
- ‘Dwarf Blue Curled’: Compact plant. Good for containers. Very cold-tolerant.
For spring planting, choose faster-growing varieties like ‘Red Russian’ or ‘Dwarf Blue Curled’. For fall, go with ‘Winterbor’ or ‘Siberian’.
Succession Planting For Continuous Harvest
To have kale all season, use succession planting. Plant a new batch every 3-4 weeks. Here’s a sample schedule for western Washington:
- March 15: Start seeds indoors for first spring crop.
- April 15: Direct sow second spring crop.
- May 15: Direct sow third spring crop (for summer harvest).
- July 15: Direct sow first fall crop.
- August 15: Direct sow second fall crop.
- September 1: Direct sow final fall crop (for winter harvest).
This gives you a steady supply from June through February. Adjust dates by two weeks for eastern Washington.
Fertilizing Kale Throughout The Season
Kale is a heavy feeder. It needs regular fertilizer to keep producing tender leaves. Here’s a simple plan:
- At planting: Mix in a balanced fertilizer (10-10-10) or compost.
- Every 4-6 weeks: Side-dress with a nitrogen-rich fertilizer like fish emulsion or blood meal.
- In fall: Switch to a low-nitrogen fertilizer (like 5-10-10) to encourage root growth before winter.
Too much nitrogen can make leaves tough and bitter. Stick to the schedule and water well after fertilizing.
Pest Management Without Chemicals
Washington’s cool, damp climate can bring pests. Here are natural ways to manage them:
- Cabbage worms: Hand-pick them off leaves. Use row cover to prevent butterflies from laying eggs.
- Flea beetles: Small holes in leaves. Use diatomaceous earth or neem oil.
- Aphids: Blast them off with a hose. Or spray with insecticidal soap.
- Slugs and snails: Common in western WA. Use beer traps or copper tape around plants.
Encourage beneficial insects like ladybugs and lacewings. Plant dill, fennel, or cilantro nearby to attract them.
Companion Planting For Kale
Kale grows well with certain plants. Here are good companions:
- Beets, carrots, onions: They don’t compete for nutrients.
- Herbs like dill, mint, rosemary: Repel pests.
- Nasturtiums: Trap aphids away from kale.
- Marigolds: Deter nematodes and other pests.
Avoid planting kale near other brassicas (broccoli, cauliflower, cabbage) to reduce disease risk. Also keep it away from strawberries and tomatoes.
When To Remove And Replace Kale
Kale is a biennial, meaning it lives for two years. But after the first winter, it will bolt (flower) in spring. Once it bolts, leaves become bitter. Here’s when to pull it:
- After it flowers: The plant puts energy into seeds, not leaves.
- If leaves become tough or yellow: It’s past its prime.
- If pests or diseases take over: Remove and compost (if no disease).
Most gardeners treat kale as an annual. Plant new crops each spring and fall for the best quality.
Frequently Asked Questions
Can I plant kale in the summer in Washington?
Yes, but it’s tricky. Summer heat can make kale bolt. If you plant in June, choose a heat-tolerant variety like ‘Red Russian’ and provide afternoon shade. Keep soil consistently moist.
What is the latest I can plant kale in Washington?
For fall harvest, plant no later than 8 weeks before the first frost. In western WA, that’s early September. In eastern WA, mid-August. Later than that, plants won’t mature before winter.
Do I need to start kale seeds indoors or can I direct sow?
Both work. Starting indoors gives you a head start and protects seedlings from pests. Direct sowing is easier and works well for fall crops. For spring, indoor starts are recommended in cold areas.
How do I protect kale from frost in Washington?
Use row cover, cold frames, or heavy mulch. Kale can survive down to 20°F without protection. For colder temps, add a layer of straw or leaves around the base.
What is the best kale variety for beginners in Washington?
‘Winterbor’ is very forgiving. It handles cold, heat, and pests well. ‘Red Russian’ is also easy and grows fast. Both are great for new gardeners.
Final Thoughts On Timing
Getting the best time to plant kale in washington right means you’ll have fresh greens for months. Spring planting gives you summer salads. Fall planting gives you sweet, frost-kissed leaves all winter. Pay attention to your local frost dates, soil temperature, and variety selection. With a little planning, you can enjoy homegrown kale from June through February.
Kale is one of the easiest and most rewarding crops for Washington gardeners. It’s nutritious, cold-hardy, and forgiving of mistakes. Start with a small patch, experiment with timing, and you’ll quickly learn what works best in your garden. Happy planting!