Now
23°C · Clear
Today
25° / 11°
Soil 6 cm
17°C
First frost
~45 days (Oct 23)
Gardening in Concord
AI field guide · refreshed weeklyConcord Garden Guide: Early September — Sow Fall Crops, Harvest Summer, Prepare for Frost
Zone 5b means your first fall frost arrives around October 23—45 days away. Soil at 17°C (63°F) is cool enough for fall brassicas and root crops to germinate reliably. You're 128 days past your last spring frost (May 3), so tender annuals are safe but won't have much time left. Frost-free days are running short; prioritize quick-maturing varieties.
Sow outdoors now
Spinach (Spinacia oleracea)
Sow 'Space' or 'Bloomsdale' directly now; germinates in cool soil and matures in 40–50 days before hard frost. Thin to 10 cm (4 in) apart.
Arugula (Eruca vesicana)
Direct-sow 'Roquette' or 'Astro'; ready in 30–40 days and tolerates light frosts. Sow thickly and thin to 5 cm (2 in).
Radish (Raphanus sativus)
Plant 'Cherry Belle' or 'Icicle' for a quick 25–30 day harvest before frost. Space 5 cm (2 in) apart in rows.
Turnip (Brassica rapa subsp. rapa)
Sow 'Purple Top' or 'Hakurei' now; roots mature in 50–70 days and improve in flavor after a light frost. Thin to 8 cm (3 in).
Mâche (Valerianella locusta)
Direct-sow this cold-hardy salad green; germinates in cool soil and overwinters under mulch for early spring harvest. Sow thickly.
Start indoors now
Kale (Brassica oleracea var. acephala)
Start 'Lacinato' or 'Winterbor' indoors now for transplanting in 4–5 weeks; these varieties sweeten after frost and produce into December. Use seed trays.
Cabbage (Brassica oleracea var. capitata)
Sow 'Red Acre' or 'Savoy' indoors for transplanting by late September; they'll head up before hard frost. Keep soil at 18–21°C (65–70°F).
Broccoli (Brassica oleracea var. italica)
Start 'Arcadia' or 'Belstar' indoors; transplant in 4 weeks for harvest before late October frost. Prefers cool weather.
Harvest now
Tomato (Solanum lycopersicum)
Pick ripe fruit now; bring green tomatoes indoors to ripen at room temperature before the first frost arrives in 45 days.
Pepper (Capsicum annuum)
Harvest mature peppers; plants will slow dramatically once nights drop below 15°C (59°F). Leave immature fruit to ripen indoors.
Cucumber (Cucumis sativus)
Pick all marketable fruit; vines will decline as soil cools. Pull spent plants and compost.
Summer squash (Cucurbita pepo)
Harvest zucchini and yellow squash at 15–20 cm (6–8 in); production slows as nights cool. Remove dead leaves to reduce disease.
Tasks this week
- Deadhead spent flowers on ornamentals to extend bloom; cut back perennials after frost blackens foliage.
- Water fall crops deeply after sowing; soil at 17°C needs consistent moisture for germination, especially if dry weather continues.
- Scout for Japanese beetles and squash bugs on remaining summer crops; hand-pick or use neem oil if populations spike.
- Mulch newly sown fall beds with 2.5 cm (1 in) compost to retain moisture and moderate soil temperature swings.
- Divide spring-blooming perennials (daylilies, coneflowers, black-eyed Susans) before soil cools; replant immediately.
Watch out for
- Powdery mildew thrives in cool, humid mornings—thin crowded plants and water at soil level to keep foliage dry.
- Deer and woodchucks browse young brassicas and greens aggressively in fall; use row covers or fencing if damage appears.
- Early frost can arrive before October 23 in low-lying areas; keep frost cloth or cloches handy for tender transplants.
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