How-to: Onions — Rio Ranch

01 Quick spec

Short-day

The only type that bulbs here

Spacing for full bulbs

~110d

Transplant to harvest

North-TX planting window: set short-day transplants in Jan–Feb (they're cold-hardy and grow through late winter), then bulb as days lengthen and harvest in late May–June, well before the brutal summer heat. Day-length, not the frost calendar, drives this crop.

02 Growing it here

Short-day or nothing

This is the make-or-break detail: at our southern latitude you must plant SHORT-DAY varieties — Texas 1015Y, Texas Supersweet, Yellow/White Granex. They bulb when days reach ~10–12 hours, which happens here in spring. Long-day or intermediate onions (sold in northern stores) will never bulb this far south — they just grow tops. Day-length is critical.

Transplants in winter

Plant as transplants (bundles of pencil-thick starts) in Jan–Feb — not in the spring with the warm crops. Set them shallow, ~1" deep and 4" apart in rows ~1' apart; closer spacing gives smaller bulbs (good for green onions). They grow leaves all winter — every leaf becomes a bulb ring — then size up fast in spring.

03 The year

Month	What
Nov–Dec	Order short-day transplant bundles (1015Y, Texas Supersweet).
Jan–Feb	Transplant starts; they're cold-hardy.
Feb–Apr	Grow tops through late winter; feed nitrogen for big tops = big bulbs.
Apr–May	Bulbing begins as days lengthen; ease off water and nitrogen.
Late May–Jun	Harvest when tops flop and brown.
Jun	Cure in shade, then store.

04 Problems & what to watch

Pests & disease

Thrips are the main pest — silvery streaks on leaves; keep plants unstressed. Onion maggots and fungal downy mildew / neck rot show up in wet ground — rotate beds and don't crowd. Bolting (flower stalks) is triggered by cold stress on oversized transplants — use pencil-thick, not jumbo, starts.

Heat

The whole point of winter planting is to finish before the heat. Bulbs size in mild spring and are harvested in early summer, so they dodge the worst of it. Onions left in the ground into the hot, wet part of summer rot fast — harvest on time.

05 Harvest & beginner mistakes

Stage	Do this
Timing	Pull when ~half the tops have flopped over and necks soften.
Curing	Garlic-style cure: dry in a shady, airy spot 2–3 weeks until necks are papery.
Storage	Trim tops and roots; store the firmest bulbs cool and dry. Sweet types keep weeks, not months — use first.

Beginner mistakes to skip: the big one — planting long-day onions that never bulb here; planting in spring instead of Jan–Feb; using jumbo transplants that bolt; over-watering near harvest (rot); and skipping the cure, which is what lets them store at all.