Repotting?

[flexy123]

Hi,

previously I didn't have a problem with repotting. I repotted once the seedlings showed signs that they're root bound, I potted them in their final pots which had been rather small 1.3gal pots.

But this time is different since we have much larger pots, 17L (4.5 gal). Now I have some seedlings going on 7" or so...would it make sense to repot them into the final large pots or would you repot into something smaller first? (If I can I'd really avoid too much repotting although I never had a problem with it).

The related question here is about the sense of repotting "right before flowering".

Here is my reasoning why I don't THINK "right before flowering" makes sense since I see that the strains we have are usually stretching/growing for two weeks once we start flowering (outside in the sun). Since this pre-flowering stretch period is only two weeks I can't see this being enough time for a plant to "fill out" a 4.5 gal pot during flowering?

My reasoning is that it makes sense to have the plants "grow as big as possible" so they really make use of the large pots. Which means to replant them into the large pots and let them veg (in my greenhouse) for at least some weeks so they can actually grow...so basically put them into the big pots during vegging? (And not bother with a medium size pot in between).

What do you say?

(Space in my greenhouse where we veg is a little limited, outside space for flowering is unlimited)
(The strains are feminized ones, not autos, I know that you're not supposed to repot autos at all and that they can go by with smaller pots)

 

[Emilya Green]

Flexy,
We successively up-pot our weeds for a very good reason. I typically do it 4 times in a grow. The reason is that these are deep rooting plants and the only way to force them to grow a solid rootball is to constrict their vertical root height in smaller containers. Just as cutting top growth promotes lower and side growth, constricting a root's downward decent sends signals to the root system to grow laterally, and that is a very good thing.

The other reason we use smaller rather than larger containers is so that we can monitor the water usage of our plants. The proper way to water is to saturate the soil of our container and then wait until the plant can find and use all that water, before we water again. In a container too large for the plant that is in it, you have no such ability, and soaking the soil can easily put you in a situation where your lower roots remain underwater all the time. There are upper roots that have to be kept alive as well as lower feeder roots... and a large container separates these two regions so completely that it is easy to kill one or the other through improper watering techniques... in a smaller container you will not have this problem, you simply saturate and wait while the water table falls, properly feeding both the upper and lower roots.
Regarding the final up-potting before flower... I think you are on to something here. I try to get my plants into that final container at least 2 weeks before flipping to flower. I have always felt it is a mistake to expect the plants to develop an expanding root system at the same time that we also tell them to switch to flower. This is why during the 8-10 weeks of flower, our plants do not become rootbound... they are mostly done growing new roots, they are growing buds.

 

[flexy123]

Ah this makes sense with forcing them to grow wider/larger roots by up-potting them often. So I'll do that then.

Yes I can totally agree also with the difficulties with watering in the large pots. We put one plant in a large container and I am having a sorta hard time to know when to water. This was not a problem in the smaller pots.

>>
This is why during the 8-10 weeks of flower, our plants do not become rootbound... they are mostly done growing new roots, they are growing buds.
>>

Yup, this is what I think as well. So it might really be pointless to up-pot right before flowering.

 

[Fuzzy Duck]

All of the above is very valid info

I start my own seeds of in peat or coir pucks.

Once roots show through the sides i pot up into some thing a tad smaller for next 1 to 2 weeks by then they should have suitable root growth for the next stage.

I use 6.5 liter air pots ye tiny by some peoples standards but they work by air prunning the roots to prevent root balling & create a more fibrous root system, yup final stage pot for another 4 to 6 weeks of veg average.

 

[flexy123]

Just some info on the side...

Any time I repot, MJ or Chillies or whatever, I do actually go through some effort to losen and shake off the soil around the root ball. I do NOT take out the entire root ball and place it like it is in the new pot. I usually carefully push/smash the root ball down to the ground a few times and watch how most of the old soil falls off. (I found this "smashing down" the best method as opposed trying to break up the root ball with my hands).

I do this once I saw that we repotted a plant with its tight root ball "like this" in another pot, and at the end of the grow I saw that the roots barely extended from the OLD root ball into the new, larger pot. (You could still clearly see the smaller, old root ball). So basically the entire repotting is pointless when you have a tight root ball, it traps the roots! I am a firm believer that loosening the root ball a little is a good thing! No worries, it won't hurt the plant, I never had a problem doing it like this.

Also, when I repot I always give a little root stimulant with the first watering.

Edit: I usually break up the root ball so that most bigger junks fall off and I can see the roots getting untangled...I don't remove all the soil. If half of it sticks still it's ok as long as you untangled the roots. Also..of course be extra careful with seedlings and younger plants.