Growing Storage Onions Part 3: Transplanting, Watering & Harvesting

By Terry Phillips.

At the end of my last blog I was off to look at seed catalogues…I enjoyed my perusal of the seed catalogues and came up with some interesting varieties to try:

‘Newburg’ open-pollinated from BC Eco Seed Co-op. (These are grown and collected by Sweet Rock Farm on Gabriola Island.) “A very heavy yielding storage onion developed by Dr. Alan Kapuler. Averages about 1/2 lb, but can grow up to a pound, and keeps for months. Sow in early spring in flats, and harvest when the tops dry down in August.”
‘Red of Florence Round’ from William Dam Seeds. “Open-pollinated red globe variety from Italy. Good quality, globe-shaped bulbs. Medium to deep red. Stores well. Good selection for bedding plant growers. Italian heirloom. Long day.”
‘Sweet Spanish Utah’ open-pollinated from William Dam Seeds. “Popular O.P. variety for large, mild-flavoured bulbs. Yellow-skinned with white, sweet flesh. Long day.” Not a great keeper apparently.
‘Patterson hybrid’ from William Dam Seeds. (Not open-pollinated so I any seed I save will most likely not be like the parent).“Long term storage. Similar to Copra in storage and firmness, Patterson uniformly produces a larger bulb with healthier foliage. Large bulbs have strong, golden-brown skin and thin, tight necks. Improved yield potential. Replaces Copra. Long day.”
‘Sturon’ open-pollinated from William Dam Seeds. “Improved storage type. Medium, flat-round bulbs have strong yellow-brown skin. Tight necks enhance potential for storage and processing. Can be used for onion set production. Suitable for spring and summer production. Long day.” It will be interesting to compare to the hybrid Patterson.
‘Evergreen Long White Nebuka’ open-pollinated from William Dam Seeds. “Long, slim, white stems. Very hardy for overwintering. Little to no bulbing.” A row of these have come through the winter and as of mid-Feb are sending up 6” tender shoots, delicious in a late winter salad.

A sampling of some types of onions:

Yellow: best storage onion with tight skins and necks.
Spanish: a type of yellow onion sweeter in flavour and flatter than other yellow onions. Not long keepers but great flavour.
Cippolini: Italian flat, button shaped, storage onions in yellow or red. Medium sized.
Shallots: French origin, tear shaped. Previously could only grow from offsets. Now available from seed. Mild flavour, crispy. Pink, red. Smallish. Mature early.
Pink: specialty onion with sweet flavour.
Red: specialty onion with sweet flavour. Some keep quite well.
White: sharp, pungent, sweet flavour, not a good storage onion.
Bunching onion: not a storage onion but are green onions/spring onions/scallions that should form a long white shank rather than a bulb.

For my onion planting tips see my previous blogs on Growing Storage Onions – Part 1: Getting Ready and Part 2: Seeds, Sets, or Starts: How Do You Decide? And also be sure to check out West Coast Seeds’ Onion Planting Guide for the juicy details. For best results follow the directions on the seed packets.

In a nutshell:

Bottom heat (21-25 C) is essential for early germination.
Ideal pH 5.5 – 6.5. That’s the acid side of neutral.
Let’s assume I have planted my onion seeds by early March so they have a good six weeks of growing before planting out in mid to late April. (See my previous blogs.)
If the garden isn’t ready and the onion seedlings are, you may need to pot up a size.
If the tops are getting leggy and falling over you could trim the tops down to 4-5”. They’ll recover and get sturdier.

Transplanting:

Around mid to late April I will assess to see if the garden has warmed up enough. If cool, I have a large piece of black plastic that can be placed on the soil for a week to help it warm up, or shed extra rain.

Choose a spot in your garden where onions will get full sun and good air circulation. Consider that onions will need to remain undisturbed for most of your growing season. And you don’t want to shade them with tall tomatoes, pole beans, or corn. Mine tend to follow the tomatoes and broad beans around year after year and are just before the greens/carrots and garlic because those crops aren’t too tall. But if I have extra I’ll also stick clumps in wherever there is space because they help deter pests. Elliot Coleman of “The New Organic Grower” says that onions can be a beneficial crop where you want to plant the cabbage family next year.

You need well-drained soil for onions. If your garden is boggy try a raised bed.

If your seedlings are about 6-8 weeks old, with a reasonably sturdy stem, they are ready for transplanting.

Push aside the winter mulch of leaves, seaweed, or other. You need fertile soil for onions; for the row where I will plant onions I will place about 6 cups of organic mix** per 10′ row. Then I will amply loosen the row with a fork the ‘width and depth’ of the fork. The amendments will fall into the loosened soil. If I dig a trench I might put my transplant mix* into the bottom.

If the roots are very long and you don’t think you can plant without bending roots then you might want to try trimming them. Onions roots are fairly tolerant of disturbance and will readily grow more.

Now for the fun part. Your seedlings can be planted in clumps of 2-4 or even more. Consider that you might harvest the smaller ones for summer eating. Holding the clump gently in one hand, plunge the other hand down into the earth the depth of the roots. Let the roots dangle into the hole. Put the next hole in about 6” along pulling the soil up to meet the first plant. Don’t transplant too deeply as the bulb needs to form on the surface. Too deep and the bulb won’t form.

Try not to plant in the hot sun where the tender roots will be exposed. If the weather is forecast for sun place a row cover over your transplants to create shade for a day or two until they adjust.

Watering:

Try to avoid overhead watering in this climate. Leaves can stay wet for too long promoting disease. Drip tape or soaker hoses on a timer should be adequate. Your mulch will help keep your soil from drying out. Keep you soil consistently moist but not soaking. Once the tops go over it’s time to stop the water.

Side dressing:

Once the onions are coming along after a couple of weeks you can place mulch near them. Be careful not to damage the fragile tops though. Seaweed, shredded leaves work well. As your onions progress put them on a regular feeding schedule. Every couple of weeks another cup of organic fertilizer sprinkled along the row and watered in.

Harvest:

Push over all the tops once half of them have fallen over naturally. Or at least by the end of August to give them time to cure and dry properly. After a week, pull the onions and cure by placing in a dry well ventilated area. Protect from rain or dew during drying. When outer skins are dry they can be braided and hung for storage in a cool location.

**Terry’s transplanting mix UPDATED**

1/2 wheelbarrow sifted garden compost
1/2 of a 40 litre bag organic steer manure or chicken or mushroom (or 1/4 barrow sifted composted manure)
4 litres (16 cups) Organic alfalfa meal (nitrogen, phosphorous, magnesium, potassium, sulfur in a good balance for plants)
1 cup bonemeal (phosphorous, calcium, iron, magnesium, zinc. Needs time to become available to the plant)
2 cups dolomite lime (has calcium & magnesium but needs a few weeks to become available to the plant)
2 cups kelp meal (60 minerals, elements, amino acids, vitamins)
1/2 cup magnesium sulfate (epsom salts; available immediately to the plant)
1 cup blood meal (optional. nitrogen available immediately, especially useful for feeding soil microbes)

In the past I have added rock phosphate, cal-phos, or greensand but I am moving away from these because of environmental issues related to mining and transporting these minerals.

*Terry’s organic mix*