The fall garden
Planning what comes after the tomatoes.
Zone 6B · Hunterdon County, NJ
“What you sow in August, you eat in December.”
- First frost
- October 10–20
- Persephone start
- November 20
- Persephone end
- January 20
- Fall factor
- +14 days
Spring gardening is a matter of getting excited and putting things in the ground. Fall gardening is a matter of arithmetic. You have a fixed deadline — the first frost, roughly October 15 in Hunterdon County — and you have to count backwards from it, crop by crop, to know when to sow. Do the math once, and the fall garden gets simpler every year after.
The framework
The math.
The formula every fall garden runs on:
Last safe sow date = First frost − (DTM + 14)
DTMis the crop’s days-to-maturity — the number printed on the seed packet. The 14-day fall factoris the correction for slower growth under shortening days and cooling soil. It’s not on the packet; it’s the reason August gardens fail.
Worked example
‘Winterbor’ kale at 65 DTM. Add 14 for the fall factor. That’s 79 days. Subtract from October 15 and you get July 28— the last day to sow that kale and still expect a full crop. Miss the window by two weeks and you’re growing 60%. Miss it by four and you’re growing baby kale.
Crops by temperature
Frost tolerance.
Not every crop belongs in the fall garden. Some are done at 32°F and no amount of row cover saves them. Others sweeten with cold and stand into December. Knowing which is which is half the game.
Semi-hardy
Tolerates light frost (28–32°F)
Handle a light frost without complaint; a hard freeze does damage. Row cover extends them another 3–4 weeks past first frost.
- Lettuce (leaf and head)
- Chard
- Arugula
- Cauliflower
- Broccoli
- Cabbage
- Bok choy
- Chinese cabbage
- Radicchio
- Beets
- Radishes
- Turnips
- Peas
- Cilantro
- Parsley
Hardy
Withstands hard frost (down to 20°F)
The winter garden. Kale sweetens after frost. Brussels sprouts need it. With row cover or a low tunnel, most of these carry you through December and into January.
- Kale (all varieties)
- Collards
- Brussels sprouts
- Spinach
- Mâche (corn salad)
- Claytonia (miner's lettuce)
- Tatsoi
- Mizuna
- Minutina
- Sylvetta arugula
- Leeks
- Parsnips (sweeten after frost)
- Carrots (protect with straw)
- Garlic (overwinters)
The other deadline
The Persephone period.
First frost is one deadline. There’s a second one, quieter and more absolute: around November 20, day length in Hunterdon County drops below ten hours. Plants can live in that light, but they can’t meaningfully grow. Whatever size a crop is when the Persephone period arrives is roughly the size it will be until it lifts again around January 20.
The practical rule: everything you want to eat between Thanksgiving and February must be at or near mature size by mid-November. Under row cover, hardy crops (kale, mâche, spinach, tatsoi) hold in that state for months. You’re not growing them through winter — you’re storing them in the garden.
When to sow what
The sow-by timeline.
Every fall crop, plotted by weeks-before-frost. The bar is the safe sowing window; the darker end is the last day it makes sense to sow. Sow earlier and you’ll have a bigger harvest; sow later and you’re gambling on a late frost.
Sow-by, counted back from first frost
Reference first frost: October 15 (October 10–20). Each bar shows the safe sowing window; the right edge of the bar is the last sensible day to sow.
Brussels sprouts
100 DTM
Start indoors early July; transplant by August 1.
Cabbage (fall)
80 DTM
Start indoors mid-July; transplant early August.
Broccoli (fall)
65 DTM
Start indoors mid-July; transplant early to mid-August.
Cauliflower
65 DTM
Fussier than broccoli. Transplant by mid-August.
Kale (fall)
60 DTM
Direct sow or transplant. Sweetens after frost — no rush to harvest.
Collards
60 DTM
Chard
55 DTM
Beets
55 DTM
Direct sow. Harvest greens young; roots by first hard freeze.
Carrots (fall)
65 DTM
Mulch heavily in October — pulls sweet through December.
Turnips
50 DTM
Lettuce (leaf)
45 DTM
Succession sow every 2 weeks August through mid-September.
Spinach (fall)
45 DTM
Overwinters under row cover — sow again in September for spring cut.
Bok choy
45 DTM
Arugula
40 DTM
Radishes
30 DTM
Succession sow every 2 weeks. Daikons and watermelon radishes need 60 days.
Mâche & tatsoi
45 DTM
Cold-hardy specialty greens; harvest all winter under a low tunnel.
240 DTM
The exception: plant 2–4 weeks AFTER first frost. Harvest next July.
The palette
Varieties that earn a fall bed.
Fall performance is variety-specific. A generic packet of kale may work; a fall-bred variety will thrive. These are the picks that reliably deliver in Zone 6B — drawn from Rutgers Cooperative Extension trials and cold-climate seed catalogs.
Kale · 'Winterbor'
Bred in Scotland; the most cold-tolerant curly kale you can grow. Sweetens dramatically after frost. Holds in the garden through most winters under row cover.
Kale · 'Red Russian'
Tender, flat-leaf, purple-veined. Best for salads when picked young. Less cold-hardy than Winterbor but faster to mature.
Spinach · 'Bloomsdale Long-Standing'
Savoy-leaf, slow to bolt, cold-hardy. The reliable fall/overwinter spinach for the Northeast. Sow in September and cover — cut fresh in April.
Spinach · 'Winter Bloomsdale'
Selected specifically for overwintering. Cover with row cover in November, pull it back in March for a jump on spring.
Carrot · 'Napoli'
Purpose-bred for fall/winter storage. 55 DTM, sweetens after frost, holds sweet in the ground under straw through December.
Carrot · 'Bolero'
Nantes-type, disease-resistant, excellent flavor. The general-purpose fall carrot for NJ.
Lettuce · 'Winter Density'
Romaine-butterhead cross. Handles cold better than any other lettuce. Sow through mid-September for a fall cut.
Lettuce · 'Rouge d'Hiver'
French heirloom romaine; deep red leaves that intensify with cold. Slow-growing but stunning in a fall salad.
Cabbage · 'January King'
The cabbage that laughs at winter. Blue-green savoyed leaves flushed purple in cold weather. Stands in the garden into January.
Brussels sprouts · 'Diablo'
Uniform, high-yielding, well-suited to NJ 6B fall. Needs the full 100 days; start indoors by early July.
Broccoli · 'Belstar'
Late-season broccoli bred for fall harvest. Produces heavy side shoots after main head is cut.
Beet · 'Detroit Dark Red'
Classic storage beet; excellent for fall harvest and root cellar. Greens are also worth eating.
Radish · 'Watermelon' (Daikon)
Large fall radish with green shoulders and pink flesh. Needs 60 days; sow by early August.
Garlic (hardneck) · 'Music' or 'German Extra Hardy'
Handle NJ winter cold better than softnecks. Bigger cloves, easier to peel, but store only 6–7 months. Plant mid-October to mid-November.
Garlic (softneck) · 'Inchelium Red' or 'Silverskin'
Longer-storing (up to 12 months) and braidable, but slightly less winter-hardy. Fine in NJ 6B with a thick mulch.
For the winter salad
Specialty cold-hardy greens.
The obvious fall crops — kale, spinach, chard — are the starting point. But a small patch of these specialty greens will put a fresh salad on the table in January under nothing more than a length of row cover. Almost none of them are available at a grocery store. Growing them is the whole point.
Mâche (corn salad)
Small, mild, buttery rosettes. Hardy to 5°F. Sow September through October; harvest all winter under row cover. The one salad green that actually loves cold.
Claytonia (miner's lettuce)
Round, succulent leaves with a mild flavor. Extraordinarily cold-hardy. Self-seeds readily. Historically eaten by California gold miners to prevent scurvy.
Tatsoi
Small dark-green rosettes with a mustardy flavor. Cold-hardy to 15°F. Cut-and-come-again through winter under cover.
Mizuna
Feathery mustard greens with a mild peppery bite. Fast to mature (35 days) and cold-tolerant. Excellent in mixed winter salads.
Minutina (buck's-horn plantain)
Narrow, grass-like leaves. Unusual texture, mild flavor. Hardy well below freezing. Almost impossible to buy fresh — grow it if you want it.
Sylvetta arugula
Wild arugula. Smaller, spicier, more heat- and cold-tolerant than salad arugula. Perennial in mild winters.
The extension toolkit
Row cover, low tunnels, cold frames.
The right cover buys you weeks. Sometimes months. The wrong cover buys you rot. Here’s what works in NJ 6B:
Floating row cover (Agribon-19 or Reemay)
Lightweight spun polyester laid directly on crops or draped over low hoops. Buys 4–6°F of frost protection and 3–4 weeks past first frost for semi-hardy crops. Under $30 for a roll that lasts three seasons. If you buy one season-extension tool, buy this.
Low tunnels (hoops + row cover, or hoops + plastic)
9-gauge wire hoops or PVC bent into arches every 3 feet, then covered. With clear greenhouse plastic (6 mil) instead of row cover, a low tunnel can extend hardy crops (mâche, spinach, kale) into January. Vent on sunny days above 40°F or the greens cook.
Cold frames
A permanent wooden box with a hinged glass or polycarbonate lid. Deepest cold protection of the three. Best for greens you want to cut all winter. More work to build; more forgiving once built. A straw-bale cold frame is the cheap starter version — four bales in a rectangle, an old window on top.
For the beds you’re not planting
Cover crops.
Any bed that will sit empty through winter should be planted with a cover crop. It costs a few dollars, builds soil, prevents erosion, and outcompetes winter weeds. The choice depends on when you want to plant that bed next spring.
Winter rye (Secale cereale)
- Sow by
- October 15
- Rate
- 3 lb per 1,000 sq ft
- Terminate
- Mow or cut down in early April, 2–3 weeks before planting
The workhorse. Germinates in cold soil, grows into December, resumes in March. Massive root system builds soil structure. Suppresses weeds. Best for beds that won't be planted until May.
Oats (Avena sativa)
- Sow by
- September 15
- Rate
- 3 lb per 1,000 sq ft
- Terminate
- Winter-kills at ~10°F — no spring termination needed
The lazy gardener's cover crop. Grows fast in early fall, dies over winter, leaves a mat of straw that peels back easily in spring. Best for beds you want to plant early (peas, spinach).
Crimson clover (Trifolium incarnatum)
- Sow by
- September 1
- Rate
- 0.5 lb per 1,000 sq ft
- Terminate
- Mow or cut before it sets seed in May (or let it bloom for pollinators)
Fixes nitrogen back into the soil — a free feed for whatever you plant next. Beautiful crimson bloom in late spring. Sometimes winter-kills in cold years; pair with rye or oats as insurance.
Hairy vetch + winter rye
- Sow by
- September 15
- Rate
- 1.5 lb vetch + 2 lb rye per 1,000 sq ft
- Terminate
- Mow or cut in mid-May before tomato/pepper transplant
The nitrogen bomb. Vetch fixes 60–120 lb of nitrogen per acre; rye adds biomass and prevents the vetch from smothering in cold. Best cover for a bed that'll grow tomatoes next year.
What’s hunting the fall garden
Fall pests.
Three problems dominate the NJ 6B fall garden. All three are manageable if you catch them early — the first week of damage is when to act, not the third.
Cabbage moth (imported cabbageworm)
Peaks in late August and September. Small white butterflies lay yellow eggs on brassica leaves; green caterpillars can strip a broccoli plant in a week. Row cover from transplant through harvest is the only reliable defense. If you catch them mid-season, spray Bt (Bacillus thuringiensis) — harmless to everything except caterpillars.
Harlequin bugs
Striking black-and-orange shield-shaped bugs that also target brassicas. They pierce leaves and suck sap, leaving pale stippled patches. Hand-pick into soapy water — they don’t respond well to sprays. Clean up all brassica debris in November so they can’t overwinter.
Slugs
Cool wet weather is their peak. Sluggo (iron phosphate) is effective and safe around pets and pollinators. Beer traps work but need refilling. Copper tape around raised beds keeps them off. Avoid straw mulch too close to lettuce — it’s a slug apartment.
One month, one crop
Garlic: the exception.
Every other fall crop is racing to mature before the frost. Garlic is different. You plant it afterfirst frost — mid-October through mid-November in NJ — and it spends the whole winter settling in. It goes dormant, then wakes in March, and by early July you’re digging heads bigger than any grocery-store garlic you’ve ever bought.
Two families to choose from:
Hardneck
Handles NJ winter cold better. Larger cloves, easier to peel, more complex flavor. Sends up a scape in June that you cut for pesto. Stores 6–7 months. Picks: Music, German Extra Hardy, Chesnok Red.
Softneck
Stores up to 12 months. Braidable stalks. Slightly less winter-hardy, but fine in NJ 6B with a good mulch. Picks: Inchelium Red, Silverskin.
What’s next
Put it into practice.
The framework’s the framework. The monthly almanac is where it lands in real time — what’s in the ground now, what to sow this week, what to cover next weekend.
Back to the almanac.