If you’re wondering when to plant kale in Seattle, you’re in the right place. Seattle’s ideal planting schedule for this hardy green is surprisingly flexible, thanks to our cool maritime climate. You can actually grow kale for much of the year with the right timing. This guide will walk you through the best dates, varieties, and tips for a successful harvest in your own backyard.
Kale thrives in cooler weather, making it a perfect match for the Pacific Northwest. It can handle our mild winters and even tastes sweeter after a frost. The key is to avoid planting it during the peak heat of midsummer, as that can lead to bitter leaves and bolting.
When To Plant Kale In Seattle
For a clear view of Seattle’s kale calendar, here are the two primary planting windows. These times align with our cool springs and autumns, giving the plants the conditions they love.
Primary Planting Windows
- Spring Planting: Sow seeds directly outdoors or transplant seedlings from late February through early May. An early start means you’ll be harvesting before summer heat arrives.
- Fall Planting (The Sweet Spot): This is often the most successful season. Plant from mid-July through early August. This schedule allows plants to mature in the cool, moist fall weather and often survive through winter for a continuous harvest.
Understanding Your Microclimate
Seattle is full of microclimates. Your specific location will fine-tune these dates. A sunny, sheltered garden in Ballard will warm up faster than a shady spot in Wedgwood. Use these schedules as a starting point and observe your own garden’s conditions.
Season-by-Season Breakdown
Late Winter to Spring (Feb – May): You can start seeds indoors as early as January for a head start. Once seedlings are sturdy, harden them off and plant them outside. Direct sowing works well once soil is workable—not soggy.
Summer (June – July): Focus on harvesting your spring-planted kale. It’s generally too late to plant new seeds now, as they’ll struggle in the drier heat.
Late Summer to Fall (July – Aug): This is your main planting time for a fall and winter crop. The soil is warm, aiding germination, and the cooling days are ahead.
Winter (Sept – Jan): Your established fall plants will slow down but keep producing. You can even over-winter kale for an early spring harvest, as it regrows from the center once days lengthen.
Choosing the Right Kale Variety
Some kale types perform better in our specific climate. Here are top picks for Seattle gardens.
- Lacinato (Dinosaur Kale): Excellent for our wet winters, with sturdy, dark blue-green leaves.
- Winterbor: A curly kale bred for cold resistance, perfect for overwintering.
- Red Russian: Tender, flat leaves that are very cold-tolerant and sweeten nicely after frost.
- Siberian Kale: As the name suggests, it’s extremely hardy and can handle heavy frosts.
Step-by-Step Planting Guide
Follow these steps to get your kale off to a strong start.
1. Prepare Your Soil
Kale likes fertile, well-draining soil. Seattle’s clay soil benefits from amendment. A few weeks before planting, mix in several inches of compost or well-rotted manure. This improves drainage and provides nutrients. Aim for a soil pH between 6.0 and 7.0.
2. Sowing Seeds or Transplanting
For Direct Sowing: Plant seeds about ½ inch deep and 1 inch apart. Later, thin seedlings to 12-18 inches apart so they have room to grow into large plants.
For Transplants: You can buy starts or grow your own indoors. When transplanting, set the plant at the same depth it was in its pot. Water them in well to settle the soil.
3. Optimal Spacing and Sun
Space plants 12 to 18 inches apart. Kale grows best in full sun, but it will tolerate partial shade, especially in warmer parts of the summer. In fact, a little afternoon shade in July can prevent wilting.
Caring for Your Kale Through the Seasons
Consistent care ensures a long, productive harvest.
Watering and Mulching
Kale needs consistent moisture, about 1-1.5 inches of water per week. Our summer dry spells mean you’ll likely need to water. A layer of mulch (like straw or shredded leaves) helps retain soil moisture, suppress weeds, and keep roots cool. It also protects overwintering plants from temperature swings.
Feeding Your Plants
If your soil is rich with compost, kale may not need extra food. For a boost, you can side-dress with a balanced organic fertilizer or more compost about a month after transplanting. Avoid high-nitrogen fertilizers late in the season, as they can make leaves more tender and susceptible to cold damage.
Pest and Disease Management
Common pests in Seattle include aphids, cabbage worms, and slugs. Check the undersides of leaves regularly. You can handpick caterpillars, spray aphids off with water, and use organic slug bait. Row covers right after planting can prevent many pest problems. Good spacing and airflow helps prevent fungal diseases like powdery mildew, which can be a problem in our damp falls.
Harvesting and Overwintering Tips
You can begin harvesting young leaves when they are about the size of your hand. Always harvest from the bottom of the plant, taking the older outer leaves first. This allows the central growing point to continue producing new leaves for months.
For overwintering, choose a cold-hardy variety like Winterbor. In late fall, give the plant a heavy mulch around its base. Even if the top leaves die back, the center will often survive and begin regrowing in February or March, giving you a very early spring harvest.
Common Problems and Solutions
- Bolting (flowering): Caused by planting too late in spring or stress from heat/drought. Stick to the early spring or fall planting windows for best results.
- Bitter Leaves: Often a result of summer heat or lack of water. Harvest after a frost for sweeter flavor, and keep plants well-watered.
- Yellowing Leaves: Could be overwatering, poor drainage, or a nitrogen deficiency. Ensure soil drains well and consider a light compost tea feed.
FAQ: Kale Planting in Seattle
Can I plant kale in Seattle in October?
It’s generally too late to plant new seeds in October. However, you can transplant well-established seedlings from a nursery in early October for a late fall harvest, especially if you use a cloche or cold frame for protection.
What is the best month to plant kale for a winter harvest?
Mid-July to early August is the ideal window. This gives plants enough time to mature before the short, cold days of winter slow their growth.
How do I protect kale from Seattle’s heavy rain?
Well-draining soil is crucial. Raised beds are excellent for preventing waterlogged roots. Ensure plants have adequate spacing for air circulation to ward off fungal issues that thrive in damp conditions.
Can kale survive Seattle snow?
Yes, most established kale varieties can survive light snow and frosts. The cold actually improves their flavor. A heavy, wet snow might damage leaves, but the plant itself usually recovers. You can cover them with a row cover if extreme cold is forcasted.
When should I start kale seeds indoors for spring?
Start seeds indoors about 4-6 weeks before you plan to transplant them outside. For a late February transplant, start seeds in mid-January. Just make sure they get plenty of light so they don’t become leggy.
Following Seattle’s ideal planting schedule for kale means you can enjoy this nutritious green almost year-round. With it’s flexibility and hardiness, kale is a rewarding crop for any local gardener. Paying attention to the simple timing tips and variety choices outlined here will set you up for a bountiful harvest through multiple seasons. Remember, the best time to start is either in the cool spring or the late summer—so you have two great chances to get it right.