onions didn't grow this year - Ask Extension
We did a soil sample in a garden bed at the end of March, in the results N was low but everything else was high. The ph was 6.32, in the optimal range...
Knowledgebase
onions didn't grow this year #851672
Asked September 29, 2023, 5:26 PM EDT
We did a soil sample in a garden bed at the end of March, in the results N was low but everything else was high. The ph was 6.32, in the optimal range. Before planting onions, I applied a fertilizer with mostly N. I planted 2 types of onions in the bed, a transpant onion set and a bulb onion set. The watering was consistent with soaker hoses, the same as other years, but the onions were not growing, after an initial 2-3 inches of growth. since there was enough space, I planted some lettuce in the same bed, it grew fine. Some volunteer oregano started growing, as well as yarrow and other weeds, which I pulled. Towards the end of July, seeing that nothing much had happened since the beginning of May, I added some inorganic fertilizer, ammonium sulphate, thinking that maybe it would be a fast N push to help out, just in case lack of N was the problem, even though I doughted it. Nothing. Here we are at the end of September and the biggest onion is maybe an inch in diameter. This is very strange, never happened to me. What do you think?
Marion County Oregon
Expert Response
Thank you for contacting Ask Extension about your onion yield. There are a number of factors that may affect bulb size, not the least of which is temperature and length of day. Onions are a cool-weather crop, and if the weather turns hot too soon after planting, they may never reach their full size. The optimum soil temperature range for germination is 48 to 90 F which generally occurs in March and April.
In our latitude, make sure that you grow either long-day onions which need about 14 hours of daylight to begin bulb formation. If bulbs form too early they may not develop to a good size.
Plant in early spring so that they are ready to start the process of enlarging when the appropriate amount of daylight is available. This article may have some useful information including recommended varieties:
https://today.oregonstate.edu/news/no-need-tears-if-you-plant-onions-soon
This article also has good information, however, it is from the state of Washington so adjustments for timing and weather may be necessary:
https://horticulture.oregonstate.edu/oregon-vegetables/onions-dry-bulb-western-oregon
Nitrogen fertilizer can be applied while the foliage is small and grassy. At this time, light, frequent irrigation should be used to minimize the leaching of nitrogen from the root zone. However, as the plants get larger and the day length gets longer, nitrogen can actually retard bulb development. Applying nitrogen to stimulate growth at this stage will actually be counter-productive.
Increase water applications as plants and roots increase in size.
I hope you find this information helpful. If you have any more questions, please feel free to write again.
In our latitude, make sure that you grow either long-day onions which need about 14 hours of daylight to begin bulb formation. If bulbs form too early they may not develop to a good size.
Plant in early spring so that they are ready to start the process of enlarging when the appropriate amount of daylight is available. This article may have some useful information including recommended varieties:
https://today.oregonstate.edu/news/no-need-tears-if-you-plant-onions-soon
This article also has good information, however, it is from the state of Washington so adjustments for timing and weather may be necessary:
https://horticulture.oregonstate.edu/oregon-vegetables/onions-dry-bulb-western-oregon
Nitrogen fertilizer can be applied while the foliage is small and grassy. At this time, light, frequent irrigation should be used to minimize the leaching of nitrogen from the root zone. However, as the plants get larger and the day length gets longer, nitrogen can actually retard bulb development. Applying nitrogen to stimulate growth at this stage will actually be counter-productive.
Increase water applications as plants and roots increase in size.
I hope you find this information helpful. If you have any more questions, please feel free to write again.
