Washington’s mild summers allow for a long broccoli growing season starting in spring. Finding the best time to plant broccoli in washington depends on your specific region and the variety you choose. Broccoli thrives in cool weather, so timing your planting to avoid extreme heat or frost is key to a successful harvest.
Broccoli is a cool-season crop that can be planted in both spring and fall in Washington. The state’s diverse climate, from the rainy west side to the drier east side, means planting dates vary. This guide will help you pinpoint the perfect time for your garden.
Best Time To Plant Broccoli In Washington
The absolute best time to plant broccoli in Washington is early spring, about 2-4 weeks before the last expected frost. For most of western Washington, that means late March to early April. For eastern Washington, aim for mid-April to early May. A second planting in late summer for a fall harvest is also highly successful.
Broccoli seeds germinate best when soil temperatures are between 45°F and 85°F. If you plant too early in cold, wet soil, seeds may rot. If you plant too late, the heat will cause the heads to bolt or become bitter.
Spring Planting Windows By Region
Washington’s geography creates distinct growing zones. Here are the general windows for spring planting:
- Western Washington (Puget Sound area): Late March to mid-April. Start seeds indoors 4-6 weeks earlier for transplants.
- Eastern Washington (Spokane, Tri-Cities): Mid-April to early May. Soil warms slower here.
- Coastal areas (Olympic Peninsula): Early April to late April. Cooler summers allow a longer spring window.
- Higher elevations (Cascades): Late May to early June. Wait until soil is workable and frost risk passes.
Fall Planting For A Second Harvest
Fall planting is often easier because the soil is already warm. For a fall crop, plant broccoli in mid-to-late summer. Count back 85-100 days from your first expected fall frost. In western Washington, that means planting from late July to mid-August. In eastern Washington, aim for early to mid-August.
Fall broccoli often tastes sweeter because cool temperatures convert starches to sugars. The heads may be smaller, but the flavor is excellent.
Understanding Washington’s Climate Zones
Washington has USDA hardiness zones from 4b to 9a. This affects your planting calendar. Western Washington is generally zones 7-8, with mild winters and cool summers. Eastern Washington is zones 5-6, with colder winters and hotter summers.
Broccoli prefers temperatures between 60°F and 70°F. In western Washington, you can grow it from spring through fall with careful timing. In eastern Washington, you need to avoid the peak summer heat.
Soil Preparation For Broccoli
Before planting, prepare your soil. Broccoli needs rich, well-draining soil with a pH between 6.0 and 7.0. Add compost or aged manure a few weeks before planting. Work it into the top 6-8 inches of soil.
If your soil is heavy clay, consider raised beds. Broccoli roots need loose soil to grow deep. Test your soil pH with a simple kit from a garden center.
Starting Seeds Indoors Vs Direct Sowing
Starting seeds indoors gives you a head start. Plant seeds in pots 4-6 weeks before your last frost date. Use a seed-starting mix and keep them in a sunny window or under grow lights. Harden off seedlings for a week before transplanting.
Direct sowing is possible but riskier. Wait until soil temperature reaches at least 50°F. Plant seeds 1/2 inch deep and 3 inches apart. Thin seedlings to 18-24 inches apart once they have two sets of true leaves.
Step-By-Step Planting Guide
Follow these steps for successful broccoli planting:
- Choose a sunny location with at least 6 hours of direct sunlight daily.
- Prepare soil with compost and a balanced fertilizer (10-10-10).
- Transplant seedlings 18-24 inches apart in rows 24-36 inches apart.
- Water thoroughly after planting. Keep soil consistently moist but not waterlogged.
- Mulch around plants to retain moisture and suppress weeds.
- Side-dress with nitrogen fertilizer when plants are 6-8 inches tall.
Common Varieties For Washington
Choose varieties suited to your region. Here are top picks:
- Green Goliath: Heat-tolerant, good for eastern Washington.
- Waltham 29: Cold-tolerant, ideal for western Washington spring planting.
- DeCicco: Heirloom variety, produces side shoots after main head.
- Belstar: Hybrid, good for both spring and fall crops.
- Arcadian: Large heads, excellent for fall harvest.
Managing Temperature And Weather
Broccoli is sensitive to temperature extremes. If a late frost threatens, cover young plants with row covers or cloches. If a heatwave hits, provide shade cloth to prevent bolting.
In western Washington, spring temperatures are usually ideal. In eastern Washington, plant early enough so heads form before July heat. For fall crops, plant so heads mature after temperatures cool in September.
Watering And Fertilizing
Broccoli needs consistent moisture. Water deeply 1-2 times per week, providing about 1-1.5 inches of water. In sandy soils, water more frequently. Mulch helps retain moisture.
Fertilize every 3-4 weeks with a balanced fertilizer. Once heads begin to form, switch to a low-nitrogen fertilizer to encourage head development over leaf growth.
Pest And Disease Management
Common pests in Washington include cabbage worms, aphids, and flea beetles. Use row covers to prevent pests. Handpick caterpillars. Spray with neem oil for aphids.
Diseases like clubroot and downy mildew can occur. Rotate crops yearly. Avoid planting broccoli where other brassicas grew the previous year. Ensure good air circulation by spacing plants properly.
Harvesting Broccoli At The Right Time
Harvest when heads are tight and dark green, about 60-100 days after planting. Cut the main head with a sharp knife, leaving 4-6 inches of stem. This encourages side shoots to develop for a second harvest.
Harvest in the morning when heads are crisp. If you see yellow petals, harvest immediately. Overripe broccoli becomes tough and bitter.
Extending The Growing Season
Use season extenders to plant earlier or later. Cold frames or low tunnels allow you to start broccoli 2-3 weeks earlier in spring. In fall, they protect plants from early frosts.
In western Washington, you can sometimes overwinter broccoli with protection. Plant in late summer and cover with row covers in winter. Harvest in early spring.
Succession Planting For Continuous Harvest
Plant broccoli every 2-3 weeks for a steady supply. Start with early varieties in spring, then switch to heat-tolerant types for summer, and cold-tolerant ones for fall.
This works best in western Washington where summers are mild. In eastern Washington, skip summer planting and focus on spring and fall.
Troubleshooting Common Problems
If your broccoli heads are small, the plant may be stressed. Check for inadequate water, poor soil, or pest damage. Thin plants to proper spacing.
If heads are loose or “ricey,” the plant experienced heat stress. Plant earlier or later to avoid hot weather. Choose heat-tolerant varieties.
If leaves turn yellow, the plant may lack nitrogen. Apply a nitrogen-rich fertilizer. If leaves have holes, check for cabbage worms or slugs.
Broccoli Companion Plants
Plant broccoli near onions, garlic, beets, and celery. These companions repel pests and improve growth. Avoid planting near tomatoes, strawberries, or pole beans.
Companion planting can reduce pest problems and improve soil health. Dill and chamomile attract beneficial insects that prey on broccoli pests.
Frequently Asked Questions
Can I plant broccoli in Washington in July?
Yes, for a fall harvest. In western Washington, plant in late July to early August. In eastern Washington, early August is better. Choose fast-maturing varieties.
What is the latest I can plant broccoli in Washington?
For a fall crop, plant no later than mid-August in most areas. In western Washington, you can push to late August if using cold-tolerant varieties. In eastern Washington, early August is the cutoff.
Do I need to start broccoli indoors in Washington?
It’s recommended for spring planting to get a head start. For fall planting, direct sowing is fine because the soil is warm. Starting indoors gives you more control over timing.
How long does broccoli take to grow in Washington?
Most varieties take 60-100 days from transplanting to harvest. From seed, add 4-6 weeks. Fall crops may take slightly longer due to cooling temperatures.
Can broccoli survive frost in Washington?
Yes, broccoli is frost-tolerant. Light frosts (down to 28°F) won’t harm mature plants. Hard freezes can damage heads, so protect with row covers if temperatures drop below 25°F.
Final Tips For Washington Gardeners
Keep a garden journal to track your planting dates and results. Note weather patterns and adjust next year’s schedule accordingly. Broccoli is forgiving, so don’t stress over exact dates.
Join a local gardening group or extension service for region-specific advice. Washington State University Extension offers planting calendars for each county. Use them as a guide.
Remember that microclimates matter. Your garden may be warmer or cooler than the general zone. Observe your own space and learn from experience.
Broccoli is a rewarding crop for Washington gardeners. With the right timing, you can enjoy fresh, homegrown broccoli from spring through fall. Start planning your planting schedule now for a bountiful harvest.