Maine’s short growing season means you should start bok choy seeds indoors to get a head start on spring. Finding the best time to plant bok choy in Maine can feel tricky, but it is simpler than you think. Bok choy loves cool weather, so you have two main windows: early spring and late summer. Get the timing right, and you will enjoy crisp, tender leaves without the plant bolting to seed too fast.
Bok choy is a fast-growing vegetable, ready in about 45 to 60 days. In Maine, your last frost usually happens between mid-May and early June, depending on your zone. Your first fall frost arrives around late September to early October. This gives you a tight but workable calendar for two crops.
Best Time To Plant Bok Choy In Maine
The absolute best window for spring planting is 2 to 4 weeks before your last expected frost. For most of Maine, that means starting seeds indoors in late March or early April. Then transplant seedlings outdoors in mid-April to early May. For a fall crop, plant seeds directly in the garden in late July or early August. This timing lets bok choy mature in cool autumn weather, which improves flavor and reduces bolting.
Your specific Maine hardiness zone matters. Coastal areas (zones 5b to 6a) warm up faster than inland or northern zones (4a to 5a). Check your local frost dates using the Maine Cooperative Extension or a reliable online tool. Adjust your planting by one to two weeks earlier or later based on your microclimate.
Spring Planting Window
Start bok choy seeds indoors 4 to 6 weeks before your last frost date. For southern Maine, that is around March 20 to April 1. For northern Maine, aim for April 1 to April 15. Use seed-starting mix in small pots or trays. Keep soil moist and temperatures around 60 to 70°F. Seedlings emerge in 4 to 8 days.
Harden off seedlings about a week before transplanting. Move them outside for a few hours each day, increasing time gradually. Plant them in the garden when soil temperatures reach at least 40°F, ideally 50 to 60°F. Space plants 6 to 12 inches apart in rows 18 to 24 inches apart. Bok choy needs full sun but tolerates light shade.
- Indoor seed starting: Late March to mid-April
- Transplant outdoors: Mid-April to early May
- Direct sow (fall crop): Late July to early August
- Days to maturity: 45 to 60 days
Fall Planting Window
Fall planting is often easier because soil is already warm. Sow seeds directly in the garden about 8 to 10 weeks before your first fall frost. For most of Maine, that is late July through mid-August. Water regularly during dry spells. Fall-grown bok choy tends to be sweeter and less likely to bolt.
If you want a continuous harvest, stagger plantings every 10 to 14 days. This works well for both spring and fall. Just remember that bok choy matures fast, so do not plant too much at once unless you plan to preserve or share.
Factors That Affect Planting Timing
Several things can shift your planting schedule. Soil temperature, weather patterns, and variety choice all play a role. Pay attention to these factors to avoid disappointment.
Soil Temperature
Bok choy seeds germinate best when soil is between 45 and 75°F. In cold Maine springs, soil warms slowly. Use a soil thermometer to check. If the ground is still frozen or soggy, wait. Cold, wet soil can rot seeds or stunt seedlings. For fall planting, soil is usually warm enough, but keep it moist for good germination.
Weather Patterns
Maine weather is unpredictable. A late frost in May can kill tender transplants. Keep row covers or cloches handy to protect young plants. Similarly, a hot spell in early fall can cause bolting. Plant fall crops early enough to mature before heat waves, but late enough to avoid summer heat.
Bok Choy Varieties
Different varieties have different maturity times. Choose fast-maturing types for short seasons. Some good options for Maine include:
- ‘Joi Choi’ – 50 days, heat tolerant
- ‘Shanghai Green’ – 45 days, tender
- ‘Toy Choi’ – 30 days, mini variety
- ‘Win-Win’ – 50 days, bolt resistant
Mini varieties like ‘Toy Choi’ mature faster and work well for small spaces or container gardening. Standard varieties need more room but produce larger heads.
Step-By-Step Planting Guide
Follow these steps for a successful bok choy crop in Maine.
- Check your frost dates. Find your last spring frost and first fall frost dates online or from local extension office.
- Start seeds indoors. Use seed trays with drainage. Plant seeds ¼ inch deep. Keep soil moist and warm.
- Harden off seedlings. One week before transplanting, expose plants to outdoor conditions gradually.
- Prepare garden soil. Bok choy likes rich, well-drained soil with pH 6.0 to 7.5. Add compost or aged manure before planting.
- Transplant or direct sow. Space plants 6 to 12 inches apart. Water thoroughly after planting.
- Mulch and water. Apply a thin layer of mulch to retain moisture and keep roots cool. Water consistently, about 1 inch per week.
- Fertilize lightly. Use a balanced fertilizer (10-10-10) at planting time. Side-dress with compost mid-season if needed.
- Monitor for pests. Watch for flea beetles, aphids, and cabbage worms. Use row covers or insecticidal soap if necessary.
- Harvest at the right time. Pick leaves when they are 4 to 6 inches tall, or cut whole heads at the base when firm.
Common Mistakes To Avoid
Even experienced gardeners make errors with bok choy. Here are pitfalls to skip.
- Planting too early. Cold soil stops germination. Wait until soil is at least 40°F.
- Planting too late in spring. Bok choy bolts when days get long and warm. Harvest before summer heat.
- Overcrowding. Thin seedlings to proper spacing. Crowded plants compete for nutrients and grow poorly.
- Underwatering. Bok choy needs consistent moisture. Dry soil causes bitter leaves and bolting.
- Ignoring pests. Flea beetles can destroy young plants fast. Use row covers from day one.
Extending The Season
Maine gardeners can stretch the growing season with simple tools. Cold frames, low tunnels, or cloches let you plant earlier in spring and later in fall. Bok choy tolerates light frost, so a cold frame can give you an extra 2 to 4 weeks on each end.
For a fall harvest, plant in a cold frame in late August. You can harvest into November if you protect plants from hard freezes. Some gardeners even overwinter bok choy under heavy mulch in mild winters, but this is risky in northern Maine.
Harvesting And Storage
Bok choy is ready to harvest when leaves are dark green and stems are crisp. You can pick outer leaves individually for a cut-and-come-again harvest, or cut the whole head at the base. Harvest in the morning for best flavor.
Store unwashed bok choy in a plastic bag in the refrigerator. It stays fresh for 3 to 5 days. For longer storage, blanch and freeze the leaves. Bok choy also pickles well if you have a large harvest.
Frequently Asked Questions
Can I Plant Bok Choy In Containers In Maine?
Yes, bok choy grows well in containers at least 6 inches deep. Use potting soil and place in full sun. Water more frequently than garden plants.
What Is The Best Month To Plant Bok Choy In Maine?
For spring, aim for April to early May. For fall, late July to early August. Exact dates depend on your local frost dates.
How Do I Know When Bok Choy Is Ready To Pick?
Leaves should be 4 to 6 inches tall for baby greens, or heads should be firm and 6 to 10 inches tall for full-size. Harvest before flowers appear.
Why Is My Bok Choy Bolting So Fast?
Bok choy bolts in response to long days and warm temperatures. Plant early in spring or late in summer to avoid heat. Choose bolt-resistant varieties.
Can I Grow Bok Choy In Partial Shade?
Yes, bok choy tolerates partial shade, especially in warmer weather. Full sun is best for spring and fall crops, but light shade can help prevent bolting in summer.
Final Tips For Maine Gardeners
Bok choy is one of the easiest cool-season crops you can grow. The key is timing. Start seeds indoors for spring, and direct sow for fall. Keep soil moist and watch for pests. With a little planning, you can enjoy fresh bok choy from your garden from late spring through early winter.
Remember that Maine’s growing season is short but rewarding. Use season extenders if you want to push the limits. And do not be afraid to experiment with different varieties. Each year you will learn more about your garden’s microclimate.
Happy planting, and enjoy your homegrown bok choy. It tastes far better than anything from the store, and you grew it yourself in Maine’s unique climate.