How quickly can a plant become pot bound?

I transplanted my 4 week old seedlings from 500ml pots to 2.5L pots last Wednesday. They were pot bound. Today I notice that they are showing signs of being pot bound again. I have roots coming out the bottom of the pot and the top of the soil. Can they really be this bound in 5 days. It is worth noting that I added Mycorrhizal root boost to the new pot.

Thanks.

Yes they can grow crazy fast looking for moisture

Thanks for the quick reply. I will have to look at potting them on again. I had banked on them being in 2.5L pots for 4 weeks.

Imo Rule of thumb I take is the roots will be twice as long /wide as the tops. I am no expert but I have had plenty of first hand experience and are only willing to help if I can.

Next grow mixed bag

speedwell68 said:

I have roots coming out the bottom of the pot and the top of the soil.

Click to expand...

ok, but this is not a sign of rootboundness. roots grow very fast to the bottom. especially if you repot they first try to "explore" the new dimension of the pot. then they leech all nutrients into them which they find and grow tall. At some point the plant is like 3 times of the potsize and if then the bottom leaves start turning yellow, then there would be a good time to pot up (actually a tad before would be optimal) or (if in your final pot) to increase the nutes.
Only pot up if the medium is well filled with roots so that if the pot is light you can take the rootball out of the pot without it breaking apart.
If you uppot too early, and/if the medium is too wet, then it may cause ripping of the roots apart - which is something to avoid