In a fit of boneheadedness, I planted onions and peas in the same row...

April 13, 2011 4:07 PM

Got distracted and planted my onion sets and my peas in the same row...

I just planted 2 rows of onions and 2 rows of peas. I noticed that one of the rows of onions didn't come up. Shortly thereafter I noticed that there were onions sprouting up in the same row as one of my rows of peas. I could pull them out and move them to the correct row but then I would wipe out the better part of one row of peas. What's the worst that would happen if I let them just co-habitate?

posted by brownrd to Home & Garden (10 answers total)

This site says that you have to separate them. Under "peas"
posted by Namlit at 4:12 PM on April 13, 2011 [1 favorite]

Best answer: As far as who to pull...the only companion planting site I found that gave a reason said that nitrogen-fixing legumes, like peas, produce too much nitrogen for alliums, like onions.

My best guess is that you could chance it, and see if conventional wisdom is an idiot? If the danger is too much nitrogen, my best guess is that the onions might put too much growth into the shoot instead of the head, which sounds like a pretty tasty spring onion to me. A delicious problem.
posted by ivan ivanych samovar at 4:27 PM on April 13, 2011 [1 favorite]

Best answer: Since peas mature very early and onions late, I'd just see what happens. Harvest the peas and then pull the plants when they're done, leaving the onions to mature alone. Could work?
posted by statolith at 4:29 PM on April 13, 2011 [1 favorite]

Oh, and especially if you dig around them enough, you should probably be able to just transplant the onions to a different chunk of the garden without too much mortality. They're pretty hard to kill.
posted by ivan ivanych samovar at 4:29 PM on April 13, 2011 [1 favorite]

I'd definitely move them, but wait until the onions have developed enough a root system to transplant without damage (that is, move them when they're the size of starts in six-packs).
To form a good head, onions can't deal with competition underground, which is why it's so important to keep onions weeded. Even though peas harvest early, I'd be worried about mature root systems around fledgling onions.
Wait a couple weeks, and then transplant the baby onions to their own row.
posted by missmary6 at 6:11 PM on April 13, 2011 [1 favorite]

Peas have long root systems that do NOT like to be disturbed. I'd let them go and see what happens. And maybe plant another couple rows of onions just to be sure.

(I'm eating my first of the season pea harvest for dinner right now!)
posted by elsietheeel at 6:15 PM on April 13, 2011 [1 favorite]

As far as who to pull...the only companion planting site I found that gave a reason said that nitrogen-fixing legumes, like peas, produce too much nitrogen for alliums, like onions.

Onions require moderately high amounts of nitrogen. Legumes only fix nitrogen in low-nitrogen conditions: the nodules that contain rhizobium do not develop, because this is a relationship that takes quite a bit of energy from the plant. So I'm not really buying the companion planting site's explanation. If you've got enough nitrogen for onions to be happy, peas won't fix nitrogen in the soil (they will a bit in their leaves, but that won't matter until they're composted). If soil nitrogen is low enough that legumes make nodules, your onions will be in very poor shape already. It doesn't make any sense from a soil/nutrition standpoint.

Therefore, I'm not sure your rows matter in any other way than spatial: what were you planning to have the peas grow on? You might need to move them to accommodate trellises, in which case you can gently dig up the little plants when the peas sprout, taking as much soil as possible, and move them, along with the onions. Otherwise, it's not going to matter where they are, horticulturally speaking, though in the future I would probably try to sort plants according to nutritional needs if I was being fussy (legumes need less nitrogen than most other vegetable crops).
posted by oneirodynia at 8:51 PM on April 13, 2011 [1 favorite]

Oh, and you will find many companion planting proponents repeating bad science, as well as good. "Peas don't like onions" seems to come straight from Louise Riotte's book, Carrots Love Tomatoes. I've yet to see any science-based reason for this assertion. Look here for better information on companion planting.
posted by oneirodynia at 9:09 PM on April 13, 2011

I'd see it not so much as a problem that peas and onions aren't good coplanters, but that your physical plant spacing is way off. If both types went in at 6" spacing, your best-case scenario is that they each have 3" of space and your worst-case is that the pea plants will get very little root space as they grow because there will be a large onion right underneath the stem, not to mention that the onion won't be particularly large or round because it will have pea roots wrapped around it. There's only so much under-soil volume, so there's some thinning to be done. All the other posters seem to know more about companion planting than I do, but in my opinion it wouldn't matter much whether you thinned by removing all the onions, all the peas, or alternating down the row. But somthing's got to come out.
posted by aimedwander at 8:04 AM on April 14, 2011 [1 favorite]

Best answer: In case anyone is wondering... both the onions AND the peas grew poorly. Oh well... lesson learned!
posted by brownrd at 6:33 AM on July 10, 2011