Leafs curling and rootbound? *PICS*

Hi guys i have these 4 plants under a 400w HPS/MH (I dont know).

Their about 3 weeks into flowering and the roots are coming out the of the 3litre pots.

Will my plants have bad effects if i leave them in the small pots and should i definitely repot them or can i leave them in these?

Also the top leaves of the back right plant is curling upwards considering it is only this plant (the tallest) that is doing it and its only at the top i presume its the heat and how the close the light is, can any1 confirm this? Thanks

PS. How can u tell what bulb u have, MH/HPS? Ive lost the packet.

Yeah, it's most likely the heat.

Look up pics of the bulbs. HPS's are usually much skinnier than MH. It should also be marked on the bulb, at the bottom just above where the threads start. The light looks to be almost definately from an HPS.

The best way we've found to handle root binding in the middle of flowering is to very carefully remove the plant from its container and add more soil. Pack the soil lightly and very gently place the plant back in. If it can handle a little more dirt, pull it out and add more. An assistant is very helpful and will keep you from having to set the plant down on its roots after pulling it out of the pot. At least a few inches of the original soil can be sticking up over the container's edge. It'll get a bit dirty with soil falling to the floor, but the plants will do much better. It will take a couple days, at least, for them to recover from any root binding.

One way to avoid this without stepping up pot size is to trim the roots when transplanting them into their flowering pots. They should be allowed at least a few days in their new pots to recover before flowering. Bigger pots is usually a better way to fix the problem, since more roots absorb more nutrients, but there are other options.

Ok thanks but their already about 3 weeks into flowering, should they still be ok?

Roots can poke out the bottom holes long before root binding sets in. It doesn't usually become a real problem until those roots that reached the drainage holes swirl around the bottom corner of the pot a few times. Your plants might make it fine and they might have problems near the end. Gently adding a few inches of soil under the existing root ball will give you some more time, but if you carefully pull plants from their pots regularly, you can watch the roots and put that off as long as possible.

Always pull plants from their pots in the dimmest light you can see the roots in. It's also a technique that should be avoided when possible but avoiding root binding is more important.

Yeah I put a green fluorescent in my grow closet so I can see and no wake my flowing plants when I need a shirt...Mothers finest is correct...