Onion Growing Guide
guide to growing Onions from seed
varieties for northern or short season areas:
-short season varieties (95 days or less, from transplant to maturity)
-storage onions for extended use
-heirloom varieties which are open pollinated, and from which seed can be saved (Onions are biannual, so that would be second year)
Seeding:
-seed viability in Onions is short, and may only last for one year.
-seedlings may tolerate a light frost (down to -5’C) so can be planted before the recommended frost free date of your climate zone (in my zone that is May 11 to may 20)
-start seedlings 8 to 9 weeks before planting outside (10 to 11 weeks before the frost free date). Assuming May 20 that would be around March 6.
-prepare cell trays by filling with soilless mix that has been pre moistened, and tamp down surface lightly so firm.
-make small divot or indentation, in the middle of each cell, with the end of a sharpie. Drop a couple of seeds in each divot, and cover by sprinkling with 1/4 inch of mix. mist to thoroughly moisten surface.
-bulk seed sowing into flats or 3 inch pots
-sprinkle seed on surface of mix (approximately 15 to 20 per 3 inch pot), and cover with 1/4 inch of mix.
-cover with plastic dome to keep moist and mist when necessary, until seeds start to germinate
-when the seedlings are a couple of inches high start exposing them to gentle air movement by placing an oscillating fan in the area
-feed with a liquid organic seedling fertilizer as per manufacturer’s instructions on the label or once a week.
-once they are 3 to 4 inches high, trim them back to 2 inches with scissors
-trim any bent or damaged leaves
Transplanting & hardening off
-harden off 1 week prior to planting out. Expose plants to the sun and wind slowly. Start with 4 hours/day on a quiet day or in a sheltered location.
-at transplanting drop some organic fertilizer pellets into the hole before placing the plant and tamping the soil firmly around it.
-I recommend to space plants 4 to 6 inches apart, and to space rows 8 to 12 inches apart. Garden conditions vary so determine spacing suitable for your growing requirements
-for bulk grown seedlings, gently remove soil from roots with fingers. separate individual seedlings and cover with soil up to slightly over the bulb where the white color ends
-this eight minute video outlines how to transplant bulk bulk grown seedlings
Feeding:
-prepare the soil by digging an organic fertilizer into the area to be planted, 2 to 4 weeks before transplanting.
-side dress (broadcast between rows) with alfalfa pellets 4 weeks after planting
Watering:
-water once or twice/week depending on how hot it is and moisture levels in soil.
Growing:
-in the first 2 to 3 weeks pull all weeds when they are still small, by hand in raised bed.
-mulch between plants with grass clippings or leaves
Pruning:
– prune older leaves that are bent over or crimped, below the damaged area in order to promote continued growth of the bulb.
-here is a short youtube video from Mlgardener about pruning Onions
Harvesting & Storage:
-stop watering a week or two before harvesting
-Onions for eating can be harvested anytime but for storage they should exhibit the following signs:
the skin where the stem attaches to the bulb becomes papery and dry
the leaves bend over and crimp the neck of the Onion, just above the bulb. At this point the bulb will not grow any larger, and can be picked
-cure storage onions in a hot dry area in a single layer for 2 to 4 weeks
-the stems and roots should be completely dried out, brown and wiry
-at this time you may cut the stem off about 1 inch above the bulb, as well as the roots
-rub any dirt off and if there is any moisture in the neck, let dry some more. If completely dry store in a container with good air circulation (gunny sack) and an area that is cool and dark