Crop Talk: Alliums
Onions are the third most consumed fresh vegetable in the United States behind potatoes and tomatoes, and as such demand to be a crucial part of a diversified vegetable farmer’s crop plan. Thankfully, there are myriad types of alliums to choose from these days without having to resort to a monocrop of Vidalias.
In order to achieve success with your alliums so customers keep coming back for more, it’s important to plan your crop accordingly. Smart planning won’t combat all Mother Nature will throw at you, but it can go a long way towards making 2019 a successful allium year. Read on for advice and resources on organic allium production.
Purchase new seeds. Allium seeds lose their vitality more quickly than almost any other seed. This means it is not a good idea to save onion seeds for multiple years in a row and expect the germination you need. Starting with new, professional quality seeds will give you the best results in the long run. Plus, growing your alliums from seed results in higher quality, longer storing bulbs than growing from sets.
Broaden your offerings. If you want to maximize your sales, maximize your offerings. Plan for successions of scallions to hit the market with early spring alliums; then make sure you have some fresh bunching types like Cabernet F1 in the rotation for midsummer harvests. Rounding out the season with reliable red and yellow storage types like Red Carpet F1 and Cortland F1 and specialty storage alliums like Matador F1 and Conservor F1 shallots will make sure your displays always look fresh, and will ensure that your customers know they can count on you for reliable onions in every season. Don’t forget to utilize optimal storage conditions if you rely on some of your onions to make it past harvest for several months.
Control weeds early and often. Many commercial farmers choose to plant onions in plastic mulch or biodegradable alternatives to minimize the required hours of cultivation needed to keep weeds from establishing competitive growth. A preferred option for some is to start with a stale seed bed and mulch with straw or other organic materials, or even to opt for a living mulch between beds, like medium red clover or white clover. Whatever your method of weed suppression, it is essential to plan for dedicating some time to mechanical or hand cultivation, no matter what. Onions have very shallow roots, so eliminating weeds early in their maturity and using the gentlest method possible while maintaining efficiency is key.
Dial in your nutrient availability. Onions require heavy amounts of available nutrients, especially nitrogen and potassium, to form hearty, juicy bulbs. To maximize your soil fertility and minimize your external inputs, plan your crop rotation so that onions follow an overwintered nitrogen-fixing legume cover crop like hairy vetch. Side dressing with blood meal, compost, or organic fertilizer every two weeks early in the season will promote vegetative growth, ultimately translating into larger bulb development. Watering is also an essential part of “feeding” your onion crop; onions grow best when they receive ~3” of water each week during the growing season, but make sure they are in well-drained soil – conditions that are too wet can result in rot and/or leaf blight.
Prepare for the inevitable pest and disease pressure. With climate change wreaking havoc on fields indiscriminately, farmers increasingly have to battle pest and disease pressure earlier and more frequently. Thrips, leaf blight, purple blotch and downy mildew are just a few of the most common enemies of a healthy allium crop. Cornell University offers some useful resources on allium pest and disease management, including how to scout for signs of damage, how to utilize different reflective mulches, and even post-harvest management of mold.
Don’t forget: onions rely on day length to form bulbs. Depending on your region’s latitude, you may need to select long-day, short-day or intermediate-day onions for best results. Read more about day length and plant growth here, and select the right varieties for your region.