How to regrow onions from kitchen scraps for free! Grow many onions from onion bottoms in pots or garden beds easily in spring & fall season!
Next time you cook with store bought or garden grown bulb onions, don’t discard the onion bottoms! This little piece of kitchen scrap has the potential to grow into multiple chubby onions!
In many climates ( even as cold as zone 5 and 6 , with winter protection) you can plant onions in both spring and fall season, which means right now is a great time to try this super fun method. There is really nothing to lose, right? 🙂
Growing onions from onion scraps is a little trickier than regrowing green onions aka scallions, aka the easiest kitchen scraps to regrow, tutorial here!
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Cut onion bottoms requires a little bit more pampering at the beginning, but it is so worth it! I will share with you some helpful tips and tricks in this how-to guide.
Step 1. Cut onion bottoms
The onion bottoms do not need to have any roots attached, because all the dried roots will be replaced by fresh new roots.
Cut off the root end of an onion about 0.5″ to 1″ thick at the thickest part. This ensures that a number of healthy stem will start to grow from the onion bottoms, and each stem will have the potential to grow into a fat onion bulb!
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Step 2. Let onion scraps grow roots.
You will see onion scraps growing in water in some tutorials. However, this method has not worked well for us. The onion bottoms would rot and mold would grow on the cut surface before any roots developed. Yuk!
As much as I LOVE growing things in water, I would always regrow bulb onion scraps in soil because it is so much easier.
Place the onion bottoms root side down in a pot filled with damp soil. The pot should have drain holes and the soil should be damp but never soggy, which can cause rotting.
Cover with a very thin layer of soil at top. These onion scraps will start growing roots in a few days and you will see green shoots in 2-3 weeks.
I have also had really good results by starting the cut onion bottoms in a shallow tray with just 1-2″ of damp soil and cover with a thin layer of soil. It’s nice to be able to add more onion kitchen scraps as we get them, and transplant those that have taken roots.
See how nice the roots grew after 1-2 weeks, even in such shallow trays? A good way to tell if an onion bottom is growing lots of roots and ready for transplanting is to gently tug it. The more resistance it has, the more roots it has grown.
You can also plant the onion scraps directly into the garden if you have the space for them.
Step 3. Regrow onions from onion scraps in pots or garden beds.
You can keep these onion scraps growing in pots for a while and use the green shoots like spring onions.
If you want to grow larger bulb onions, then do not trim the onion greens since they feed the bulbs. you will also need to plant or transplant the rooted onion bottoms in larger pots or in garden beds.
Above is a really good video tutorial on growing onions in the garden.
As you can see this piece of onion scrap growing in a small pot already has five onion bulbs developed just after a month! It’s going into our garden next. Talking about growing FREE onions! 🙂
This photo above shows another piece of onion scrap that we planted in the garden. Three bulbs grew from it, and one is already really big!
If you need more tips on how to grow onions, here‘s a great guide on planting onions in fall season.