Now
25°C · Clear
Today
25° / 8°
Soil 6 cm
18°C
First frost
~44 days (Oct 22)
Gardening in Boise
AI field guide · refreshed weeklyBoise Garden Guide: Early September – Sow Fall Crops, Harvest Summer Bounty
Zone 7a with 44 days until your average first frost (Oct 22). Soil at 18°C (64°F) is ideal for fall seed germination. You're in the sweet spot: warm enough for quick sprouting, cool enough that seedlings won't bolt before frost. Plant now for a full harvest cycle before November.
Sow outdoors now
Spinach (Bloomsdale, Space or Tyee)
Direct sow now; germinates in 7–10 days at soil temp 18°C. Ready to harvest in 40–50 days, well before frost.
Arugula (Roquette)
Fast crop (30 days to baby leaves, 50 to full size). Sow thickly in rows; thin as you harvest. Thrives in cool fall weather.
Radish (Cherry Belle, French Breakfast)
Matures in 25–30 days. Sow every 10 days through mid-September for continuous harvest into October.
Peas (Oregon Sugar Pod, Cascadia snap peas)
Sow by mid-September for October harvest. Needs trellis or support; germinates well in cooling soil.
Lettuce (Winter Density, Buttercrunch)
Sow now for fall harvest; cold-hardy varieties tolerate light frosts. Succession-sow every 2 weeks through September.
Start indoors now
Broccoli and Cabbage transplants
Start indoors now; transplant outdoors in 4–5 weeks (mid-October) for November harvest. Brassicas need 6–8 weeks total to mature.
Kale (Lacinato, Winterbor)
Sow indoors now for transplanting in October. Cold-hardy and improves in flavor after frost.
Chard (Bright Lights, Fordhook Giant)
Start indoors for October transplant, or direct sow outdoors now. Tolerates light frost and regrows after cutting.
Harvest now
Tomatoes (all varieties)
Pick all remaining fruit before first frost (Oct 22). Ripen indoors on a sunny windowsill; green tomatoes will mature in 2–3 weeks.
Peppers (sweet and hot)
Harvest mature peppers now; immature ones won't ripen before frost. Leave on plant as long as possible for color and heat.
Summer squash and zucchini
Pick regularly to encourage continued production through September. Check plants daily; they grow fast in warm weather.
Beans (snap and pole)
Harvest pods when tender and snap cleanly. Production slows as nights cool; pull plants by late September.
Tasks this week
- Deadhead spent flowers and remove diseased foliage to redirect energy to fruit and seed production.
- Water deeply in early morning; soil is still warm and dry. Mulch around plants to retain moisture and moderate soil temperature.
- Scout for spider mites and aphids on warm days (forecast highs 25–33°C); spray with water or neem oil if needed.
- Begin cleanup: remove bolted lettuce, finished peas, and spent annual flowers to reduce pest habitat.
- Stake or trellis fall peas and any late-sown beans now, before they sprawl.
Watch out for
- Sudden temperature swings: highs near 33°C mid-week, then dropping to 12°C by weekend. Water consistently and mulch to buffer soil.
- Strong winds (up to 28 km/h) forecast mid-week—stake tall plants and protect young transplants with row cover if needed.
- Powdery mildew thrives in cool, humid mornings; ensure good air circulation and avoid overhead watering in evening.
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