Why shouldn't I put small plants in bigger containers?

October 17, 2009 1:50 PM

I've read that it's a bad idea to plant small plants into larger pots (the idea being that they will grow into the large pot). Instead, you're supposed to keep the plant in the smallest appropriate container and move up as it grows. Why? What will happen if I just start a plant in a container that's bigger than it needs?
posted by tumbleweedjack to home & garden (7 comments total)

The potting medium will retain too much moisture, and the roots are likely to rot. That's what happens to orchids, anyway...
posted by aquafortis at 1:57 PM on October 17 [1 favorite has favorites]

My understanding has always been that the roots will then expand and grow rather than the actual visible plant.
posted by jgirl at 2:43 PM on October 17

If you're starting many small plants, it saves space and potting soil to start them in small pots, and then transplant the ones that look most viable into larger pots, discarding the others.
posted by Knappster at 2:48 PM on October 17

You also run the risk of fungus gnats, which are harmless but annoying.
posted by moonshine at 3:19 PM on October 17

I think it depends on the plant, how you treat it, where you grow it, etc. I frequently pot several small plants together in a large pot, in this case coleus, periwinkles, begonia, etc. I've often found them coming that way from the garden center. I have other things that break off, like kalanchoes or pothos, where I just stick a small plant or cutting, maybe with or without roots, into a pot clearly "too large" and it grows. YMMV - really!
posted by Robert Angelo at 3:33 PM on October 17 [1 favorite has favorites]

The wikipedia "Houseplant" writeup agrees with aquafortis.
posted by path at 4:58 PM on October 17

It's all about moisture management. If you're watering thoroughly (as you should), then soil in a bigger pot will stay wet longer, all things being equal.

With most plants, you want the soil to dry out every few days. (Some plants completely dry, others just mostly dry.) Soil that stays perpetually moist tends to rot and attract fungus gnats.

So... There's nothing wrong with a bigger pot. But you have to take measures to get it to dry out sooner - use a less moisture-retaining potting mix, one with lots of perlite or vermiculite. Potting mix based on peat moss rather than real soil is less likely to rot. Put lava rock at the bottom of the pot to encourage drainage.

Since this is a lot of trouble, I usually just use a smaller pot anyway. But if I have a larger pot in mind for the plant and know it will grow into it, I fill the large pot halfway with rocks, insert the smaller pot, and then fill in the space with rocks or moss. That way the plant looks good, and when it gets a bit bigger all I have to do is throw out the small pot and pot the plant in the big one.
posted by mmoncur at 2:32 AM on October 18