Crop fact sheet · Cool season
Onions (bulb, short-day)
Not in season right now in Houston. Dates below.
Your dates in Houston
| Window | Order seed by | Start indoors | Plant | First harvest |
|---|---|---|---|---|
| Fall 2026 | Sep 9 | — | Sep 30 – Oct 14 | from Dec 19 |
| Spring 2026 | Nov 16 | — | Dec 7 – Jan 18 | from Feb 25 |
| Fall 2027 | Sep 9 | — | Sep 30 – Oct 14 | from Dec 19 |
Worked out from AgriLife planting windows (days before/after average frost) and Houston's average frost dates. "Order seed by" is our own 3-week heads-up, not an AgriLife date.
The numbers
- How to plant
- Set out transplants 0.75" deep, 3" apart, rows 14" apart.
- Days to harvest
- 80–120 days
- Yield per 10 ft of row
- 10 lb
- Sun
- Full sun
- Family
- Amaryllidaceae (for rotation)
Water
Water about once a week in spring, more often in dry, windy weather; water slowly and deeply. Stop watering when the tops begin to fall over; moisture stress causes split and double bulbs.
Feeding
- At planting: 2-3 lb of fertilizer such as 10-10-10 (or 15-5-10) per 100 sq ft, mixed into the top 3-4 inches of soil.
- 5-6 leaves: Side-dress about 1/2 cup per 10 ft of row (1 1/2 cups if organic), scratched into the top inch between rows and watered in.
Not sure what your soil needs? Get a soil test first.
Texas heat
Onions bulb earlier in warm temperatures (bulbing favored at 70-80°F with the right day length) and hot, dry weather suits maturity. Bolting is caused by cold, not heat: pencil-size plants exposed for long periods to low-to-mid 40s°F, especially after fast early growth, tend to bolt.
Pests to watch
- thrips
- onion maggots
- cutworms
- armyworms
- wireworms
Diseases
- pink root
- purple blotch
- downy mildew
- Botrytis leaf blight / neck rot
What to do about them: pest sheet · what's wrong with my plant?
When it's ready
Dry bulbs are ready when the main stem weakens and the tops fall over (bulbs 2-4 inches across). Don't harvest when soil is wet. Green onions can be pulled at pencil size.
Storing it
Leave pulled bulbs in the garden 1-2 days to dry, clip tops about 1 inch above the bulb and remove roots, finish drying in baskets or boxes, then store in a refrigerator crisper or a dry, airy place such as a wire rack in a garage.
Texas tips
- Texas grows short-day onions (bulb at 10-12 hours of daylight). Set transplants (or sets) 3/4 inch deep, 3 inches apart, mid-January to early February; never deeper than 1 inch.
- AgriLife table: onion plants 4-10 weeks before the last spring frost; fall planting of plants is 'not recommended'. The fall window shown here is for SEED (8-10 weeks before first freeze; seed is sown October-December).
- Onions planted Oct-Dec (seed) or Jan-Feb (transplants) produce bulbs May to July. Days to harvest from transplants: 85-95 per Masabni onion sheet.
- Don't plant garlic after onions.
Varieties that do well in Texas
TX 1015Y (Texas Supersweet), Early Grano 502, Granex, Texas Early White, Crystal Wax, Red Burgandy, Legend, Candy (intermediate/long day)