Fresh onions and leeks from your own garden have a sharpness and complexity that store-bought versions simply can't match! Grocery store onions may have been in storage for 6 - 8 months, while leeks lose their delicate texture within days of harvest. Both members of the allium family, onions provide the foundation for most savory cooking, while leeks add mild onion flavor to soups, braises, and roasts without overpowering other ingredients.
Bonus: Green onions can be succession planted every few weeks for continuous harvests in just 30 - 60 days, giving you fresh garnishes while your main crops mature.
Onion Fast Facts:
Cool or warm weather: Cool tolerant to adaptable
Size: Large
Sun: 6 - 8 hours
Days til maturity: 100 - 120 days
Water: Consistent moisture
Original or Leaf GreenStalk: Either
GreenStalk level: (depends on what else is in the planter) any level
Plant support needed? No
Leek Fast Facts:
Cool or warm weather: Cool tolerant to adaptable
Size: Large
Sun: 6 - 8 hours
Days til maturity: 100 - 150 days
Water: Consistent moisture
Original or Leaf GreenStalk: Original (needs deep pockets)
GreenStalk level: (depends on what else is in the planter) any level
Plant support needed? No
Planting & Growing
A single GreenStalk Original Vertical Planter can produce 30+ onions or 40+ leeks from just 2 square feet, with one onion or 1 - 3 leeks per pocket. The deep pockets in the Original provide ideal root depth without the laborious soil preparation required for ground growing, while elevated positioning makes harvest easier and reduces pest pressure.
Best Onion Varieties for Container Gardening
Onions form bulbs based on daylight hours, so choose varieties suited to your region. Long-day varieties (like Copra and Pontiac) need 14 - 16 hours of daylight and work best in northern states. Short-day varieties need only 10 - 12 hours of daylight, making them ideal for southern regions. Intermediate-day varieties (like Candy) need 12 - 14 hours and work reliably across most growing zones.
For southern growers in zones 7 and warmer, try Texas Early Grano (sweet, early-maturing), Vidalia (exceptionally sweet for fresh eating), or Red Creole (spicy-sweet with excellent storage life) — all favorites of the GreenStalk growing team.
(Almost) instant gratification: Evergreen White Nebuka and Tokyo Long White produce tender green onions ready in 30 - 60 days, and the tops will regrow after cutting.
Red Creole, a short-day onion
Reliable Leek Varieties for Your GreenStalk
Musselburgh is a reliable Scottish heirloom that produces thick, 8 - 10 inch white stems in 130 days and handles cold well. King Richard offers quicker results at 75 days with tender, slender stems. Toledo develops long stems for late-season harvest from November through February.
Place leeks in the Original Planter where pockets are deepest — they need at least 10 inches of soil depth. Green onions work in any space since they only need 4 - 6 inches of depth.
Plant one onion per pocket, 1 - 2 leeks per pocket, and 6 - 8 green onions per pocket, or you can plant a couple green onions around onions and leeks to maximize space!
Start onion sets in early spring, 4 - 6 weeks before last frost. Seeds require indoor starting 8 - 10 weeks before transplanting. Plant leek transplants deep in the pocket, burying most of the stem to develop longer white portions.
Leeks growing in an Original Vertical Planter
Watering & Fertilizing
Both onions and leeks are sensitive to overwatering, making GreenStalk's patented slow-drip watering system ideal for these crops. Water when you can stick your finger into the soil up to your second knuckle and it feels dry — typically once or twice weekly in cool spring weather, more frequently as temperatures rise through late spring and summer. For consistent results without guesswork, the GreenStalk Spring Watering System connects directly to your hose and delivers precise moisture to the reservoir.
Both crops are heavy nitrogen feeders. Start with a quality potting soil and incorporate granular fertilizer like Fox Farm Jump Start 3-4-3 into the lower two-thirds of your soil before planting. Follow up with liquid feeding using Fox Farm Grow Big 6-4-4 as directed once plants are established. Stop feeding onions 4 - 6 weeks before harvest to encourage proper curing.
Harvest & Storage
Onions signal readiness when tops fall over and turn yellow-brown, affecting 2/3 of the crop at once. Stop watering once tops start falling and harvest within a week. Gently lift bulbing onions by the stem just above the bulb.
Leeks can be harvested once stems reach 1 inch diameter by either cutting at soil level (to promote regrowth) with clean shears or harvest to the root system just like an onion before cooking.
Green onions are ready when 6 - 8 inches tall with pencil-thick white stems. They can be uprooted or cut just above soil level to prompt additional growth.
For storage, onions require 2 - 4 weeks of curing in a warm (75 - 80°F), dry, well-ventilated area. Spread bulbs in single layers on screens or hang in small bundles until outer skins are papery and necks completely dry. Store cured onions in mesh bags or baskets in a cool, dark location. Well-cured varieties keep for 6 - 10 months.
Leeks and green onions keep 1 - 2 weeks refrigerated or can be blanched for 2 - 3 minutes and frozen in portions.
A Note on Succession Planting
Here's a practical approach that maximizes your GreenStalk: plant green onions every 2 - 3 weeks for ongoing 30 - 60 day harvests, while your main onions and leeks (or other crops) mature in deeper pockets below. It's an easy way to get both quick harvests and long-term pantry staples from the same footprint.
What are your favorite allium varieties? We’d love to hear what works for you at support@greenstalkgarden.com.
