Long-day, intermediate-day, and short-day onions may seem intimidating for beginner growers due to the many variables at work in timing and placement. Unfortunately, this means onions tend to go underappreciated in our gardens due to this confusion, often overlooked for more ornamental leeks or faster-growing bunching varieties. Nevertheless, they deserve our full consideration as bulbs of great potential.
I hope to do just that in this article by simplifying some of the terms used to describe their growing conditions; such as light levels, climate parameters, and day length. Starting by discussing which varieties work well for particular uses before moving on to when planting Long-day, intermediate-day, and short-day onions would make sense to grow successfully.
The Difference Between Long-Day, Intermediate-Day, and Short-Day Onions
At first glance, distinguishing Long-day, intermediate-day, and short-day onions (sometimes known as day-neutral onions) seems easy. Their names suggest their characteristics. Yet short-day onions require further clarification for further understanding. Where do we typically find these kinds of varieties and when should one be harvested?
First and foremost, your onion planting schedule depends more heavily on where and when it takes place than on what season of the year it happens. In Northern states for instance, short-day onions tend to form bulbs too soon in short days due to climate and start producing weaker bulbs with too much strain put upon young roots.
But why does it matter? Onion bulbs grow based on the strength of their leaves above ground; roots provide food to these leaves which in turn grow stronger over time; more leaves above ground equal more rings within its bulb underneath round.
Onion leaves are directly tied to their bulbs; an onion with 15 leaves will produce 15 rings when planted in its entirety. Unfortunately, planting short-day varieties too far north results in bulbs being produced even before their leaves have completed or begun growing properly.
Day Length for Onions (Long-Day, Intermediate-Day, And Short-Day Onions)
In northern states with lower light levels and cooler temperatures, where daylight hours tend to extend further due to higher daily sun hours than usual, any variety of long-day, intermediate-day, and short-day onions can be planted at once, just in different spots.
North of Nevada, long-day onions are an indispensable choice since each day spans 14-16 hours between late spring and mid-autumn.
States located across the center of the US (from Nevada to Virginia) typically need 14 hours of sunlight to produce bulbs. Again this would happen around the same time of year as for northern states but day length may differ slightly.
Short-day onions are an ideal option in Southern states with long days that reach 10-12 hours by late spring, as their planting method usually works better from sets rather than seeds and therefore does not need overwintering. Planting young sets in early spring will allow a full season’s growth!
Long-Day Onions:
Long-Day Onions Long-day onions should be planted in early spring or overwintered if started from seed in late autumn; indoor winter growing could produce stronger spring growth but will require greater maintenance as your onions may become top-heavy with too much top growth before bulbs form.
When To Plant Long-Day Onions?
As soon as the day length exceeds 14 -16 hours and your onions have been planted in an ideal sunny location, they will begin producing bulbs underground. Usually in early summer in Nevada. Long-day onions should never be grown south of Missouri as day lengths do not enable sufficient bulb formation.
Temperatures north of Nevada make growing long-day onions unreliable in winter; therefore it is recommended to plant long-day onion sets in early spring, after the last frost has subsided, to give their roots enough time and space to develop roots before becoming leaf-bearers. This also gives maximum growing time when planting from sets which gives your long-day onions maximum chances to form leaves at maturity. These long-day onions offer optimal conditions for optimal harvests.
Best Long-Day Onions For Growing
- Ringmaster Long-Day Onions: These beautiful onions boast bright white skins which make them the ideal onions to store or hang up and display. Their close spacing helps maximize growing space while their long storage lifespan guarantees they can survive throughout winter if stored correctly.
- Red Zeppelin Long-Day Onions: Red onions tend to be problematic for storage; their wetter centers tend to dry out faster and need individual wrapping even after being stored in a greenhouse for some time. Red Zeppelin onions. However, offer great storage potential with its rich red skin often producing bulbs the size of squashes; therefore storing exceptionally well.
These long-day onions are among the sweetest available to purchase, providing delicious flavor at every bite.
Intermediate-Day Onions:
Day-neutral onions also referred to as intermediate onions, are ideal for growing in central states due to being considered safer varieties. Their bulbs begin forming at approximately 12-14 hours of light per day. Early summer planting for optimal top growth before their bulbs form.
Though a variety of options are less available, growing long-day onions for storage purposes is still possible. When grown in intermediate states they will produce smaller bulbs but taste just as great.
When to Plant Intermediate Onions?
Plant intermediate onions in early or mid-spring; planting too early can result in overgrown leaves which put too much strain on their bulb. Long-day and short-day onions have proven their resilience against environmental challenges; intermediate varieties are less suitable.
As they will likely be ready for harvest later, planting them during mid-spring should provide ample time for establishment while not giving too much space for flowering to occur. This way, their leaves have time to develop without going full bloom too early on!
Best Intermediate Onions to Grow
- Cabernet Intermediate Onions: Cabernet onions are classic red onions with deep, almost purple skins and soft pink-hued rings that turn from soft red to soft purple as the day progresses. Though not quite as sweet, they cook up perfectly well!
- Red Candy Apple Intermediate Onions: Red Candy Apple Onions are reliable in most climates and offer wider growing areas than many intermediate onions, thanks to their superior frost tolerance and speedy bulb growth. When growing them further north than Kansas, set seed rather than planting from seeds as this gives your crop the best start possible for success.
Short-Day Onions:
Short-day onions have sweeter, rounder flavors. When grown properly, short-day onions make excellent food preparation tools and offer more culinary flexibility than their longer counterparts. If possible, grow short-day onions as these make excellent cooking partners.
Even though these varieties require specific growing conditions to flourish, those lucky enough to successfully cultivate them should take every opportunity available on our veg plots to incorporate these crops.
Since dahlias produce bulbs within 10-12 hours of sunlight per day, planting south of Missouri is essential. Otherwise, they’ll begin producing bulbs before their leaves and roots have fully developed; leading to small bulbs without enough layers that bloom prematurely in their first year, rendering the harvest unusable for consumption.
When To Plant Short-Day Onions?
Plant short-day onions in winter. Assuming you live further south, chances are greater of success with leaving short-day onions outdoors for extended periods. Since short-day varieties tend to be frost tolerant and frost risk is generally reduced in southern states, planting from seed in autumn or setting sets out in October will give your onions plenty of time to establish stronger roots and more leaves before reaching 10-12 hour daylight length. This gives ample energy ready to be channeled back into their bulbs when summer hits.
Best Short-Day Onions For Growing
- Red Creole Short-Day Onions: Red Creole onions make excellent short-day onions. Their sweeter flavor makes Red Creoles ideal, and choosing brighter red varieties will only amplify that experience when harvesting time comes around. You may just end up snacking like apples.
- Texas Early Grano Short Day-Onion: If there’s anything better that identifies short-day onions than being labeled Texas varieties, please let me know immediately. It doesn’t get much Southerner and you know they will remain reliable overwinterers too!
Surprisingly, these bulbs store quite well despite having flat bulbs which often indicate mold growth when stored; I’ve found they fare pretty well through most winter storage conditions.
Do you wanna know How to Plant Fall Onions?
Conclusion
Understanding Long-day, intermediate-day, and short-day onions is equally as crucial for all. My friend once brought back from Greece a bag of onion sets that bloomed before summer was up. Although buying incorrect onion varieties on holiday should only ever occur rarely, be wary when purchasing any imported varieties from similar climates.