Don't seem to be able to grow tall plants? Help please

First of; thanks for taking the time to read and potentially offer advice.

A brief background. This is my second grow.
My first one is 4 weeks away from harvest (picture attached, ignore the seedling that's there, just experimenting with an auto)
They're in a 1.2m X 0.6m X 1.5m tent.

The crux of the post!
I have a 200w CFL, and I've got 4 plants under it in 4 gallon smart pots which are 4 weeks old.
They're in a 0.8m X 0.8m X 1.5m tent.

For the last 2 days, and for the next 4 weeks they've also got 4 X 26w 6400K CFL bulbs, on one side. (Rotating the plants positions every 2 days) to provide light to the lower canopies on a 4 plants.

I am using the following seeds, all FEM photo's;

2 X Blue Cheese (Barney's Farm)
1 X Seamango (Victory seeds)
1 X Red Russian XXL (Victory Seeds)

I'm using Canna Terra professional soil mix, and they're currently 4 weeks into veg.
They have 4 weeks left, before I put them into flower under a 315W CMH.

So far I've only watered them with PH neutral water, and one foliar spray with Maxicrop liquid seaweed (plus sequestered Iron)
The compost I am using is supposed to have a fair chunk of nutrients in already and none of the plants are showing signs of nutrient deficiency.

These 4 plants have all got mycorrhizal fungi, added when I transported them from their seedling pots to these bigger smart pots.

Tomorrow they will get Fulvic acid, via a foliar spray. 10mls in 1L of water.
This is their first application, as only just discovered this stuff whilst listening to postcasts.

I'm intending on giving them 'Grow' nutes (plant magic) in 3 weeks. That's 1 week before they then get flipped to flower and begin their stretch.

I'm seeing people talking about plants reaching 1M+ in height, yet I've done one grow prior, the plant reached 0.42m (42cm/420mm) at end of stretch.

These 4 in veg are currently at 0.24m (24cm/240mm) height.

Any ideas what I might be doing wrong?
Attached pictures of current vegging grow.




Below is the first grow I ever did. (Started 12 weeks ago, ending in 4 weeks)
Notice how they're not that big either?

Root space & apical dominance usually regulates how tall/wide a cannabis plant can get.

When you top/fim/lst you are dividing apical dominance which means your plant will put more energy into growing like a bush instead of a christmas tree, if your root zone is limited on space your bud sites usually stay somewhat small until you up pot & give more veg time.

They look hungry too. Genetics are huge, and everything above too... light intensity helps too...

I've topped one of the Blue Cheese, and left the other 3 plants. Hopefully that's why my other grow didn't get that big, because I topped them too early.

Thanks for your reply guys.

mannurse801 said:

They look hungry too. Genetics are huge, and everything above too... light intensity helps too...

Click to expand...

What do you mean they look hungry?
You think I should add some nutes?

The veg ones are pale looking.It may just be the camera. You have good additives to the soil, so unsure about adding more, dont want you to burn anything...

Genetics have a big role in this, and so does veg time.
Some plants will double or more in height when put into flower, so with some strains, if you start at .5m when you switch to 12/12 you may very well end up with a 1m+ plant by the time stretch is over. Some strains barely stretch at all.
If you really want them taller, use light in the 3000-3500k range, that will make them stretch a bit more. Also put the lights higher to make them reach for it. If you just want tall for the sake of tall.

I guess the bigger question, though, is why you want taller plants? Taller doesn't necessarily equate to higher production. In fact, shorter and wide with an even canopy is probably better for that (scrog, sog, manifold, etc).

Or if you really just want them tall, you could add a far red supplemental light.

Do You use Fans?

i get bigger plants under 25watts referring to veg not flower. dont need that much light to veg. i find too much make them grow slower with fatter stems. i dont know about them autos though

one thing i've noticed is that if i repot more than a week or ten days before i flip, the plant fills the pot with roots and doesn't have a lot of room to grow once it gets flipped. now i wait till i'm sure i'll have room for it within a week, then i repot. they have time to get established in their new pot, but not time to fill it up, so they have room to stretch in the flower room.
the bigger you let them get in flower, the bigger they'll get once you flip them. i don't flip till they're between 18-24 inches high. they usually double in size, sometimes a little more or less, but that's the average.
i also try to do all of my trimming and shaping a few days before i do that last repotting. much less stressful on the plant if its done before it starts trying to flower

fulvic acid works a lot better as a root drench. it's not completely ineffective as a foliar spray, but it just works a lot better in the root zone.

It depends on the plants size before flip. Depending on the genetics plants can double or more in size under certain conditions. With tiny plants like that you can't expect to get the same results.

You may want to try using grow bags to get more air to the roots.
Edit: I was looking at your old grow.

Is your CFL blue or red spectrum? Blue will reduce length between nodes.

Put some actual light on them. I see none listed in your details.

Roger A. Shrubber said:

one thing i've noticed is that if i repot more than a week or ten days before i flip, the plant fills the pot with roots and doesn't have a lot of room to grow once it gets flipped. now i wait till i'm sure i'll have room for it within a week, then i repot. they have time to get established in their new pot, but not time to fill it up, so they have room to stretch in the flower room.
the bigger you let them get in flower, the bigger they'll get once you flip them. i don't flip till they're between 18-24 inches high. they usually double in size, sometimes a little more or less, but that's the average.
i also try to do all of my trimming and shaping a few days before i do that last repotting. much less stressful on the plant if its done before it starts trying to flower

fulvic acid works a lot better as a root drench. it's not completely ineffective as a foliar spray, but it just works a lot better in the root zone.

Click to expand...

I do it the same way with small plants, once maturity kicks in i hit them with a 3 or 5 gallon and flip in 4-5 days, Works nice for water only grows.

I noticed the roots dont slow down untill like week 3 of flower and also noticed the more room i have on the bottom of the pot during transition, the more they can stretch during transition/early flower.