Priming seedlings to grow their roots downwards vs no limits?

I know they grow down first and foremost, but I'd like to see some comparison on growing in a deeper and narrower seedling container vs a broader and shallower one.

I had an amazing yield of chilies on a very small plant last year, so root development is really important and interesting.

So preferably I'd like an answer to this question, but it would be interesting to know what can be done to develop the roots better/faster as well. Or some good source to read further.

Thank you!

For starting plants that you want to transplant into regular garden beds Taller containers are best, you want to be able to plant these out and have the roots go deep enough to help reduce the amount of watering needed to keep them growing well.

Shallow containers promote root spiraling so you end up with a compact root ball that will never expand out unless you do some root cutting and tweezing as you plant them out.

To really give plants a kick in the roots you want to water them with a solution that contains things like B-12, Iron, calcium, and other minerals, other vitamins don't hurt either.

I like to make use of out of date multi-vitamin/mineral tablets for this, just dissolve up to 6 in a gallon of water then dilute 1:10 and use that to water in each of the transplants.
You can even make it up once a month for a monthly booster dousing.

Yes, I'm hoping to prevent spiraling as well, so that sounds good. And will be planting the chilies in self-watering pots, so it would be good if the roots are getting down to the water pretty fast.

I haven't even heard of watering with vitamins. But I will be looking into it.

But I want to be careful to not invite mold or bad bacteria though...

Thank you for a helpful answer!

I guess the initial question I asked isn't so important, just as long as you take care of the roots with all the best methods you can find. I just wanted to see if I could find a simple shortcut.

I use the tall tree pots. They’re square and tapered toward the bottom.
My seedling’s roots always head straight down.

Wayne Mackenzie wrote:I use the tall tree pots. They’re square and tapered toward the bottom.
My seedling’s roots always head straight down.

Well, for now I just have tall but small seedling pots (4x4 cm wide and 7 cm deep), then transferring them pretty quickly to 25x25x35 cm self-watering pots.

I also found this when looking into vitamins for plants:

Some yeasts and plant-growth-promoting rhizobacteria produce B-vitamins directly on the surface of plant roots. The B-vitamins stimulate the metabolism of the root cells, and help activate the plant’s natural defence mechanisms against environmental stress and foreign invaders. For example, scientists now know that thiamine (B1) activates the plant’s systemic acquired resistance in a process called “priming”. When treated with B1, the plant becomes highly “sensitised” so that it can respond more quickly against various pathogenic bacteria, fungi and even viruses. In one experiment, a single treatment with thiamine provided increased plant protection for up to 15 days!

So B1 seems to be the safest bet for safely supplementing with vitamins. Perhaps a protocol of priming with B1 and then after a week or so using other vitamins and a low nitrogen fertilizing formula (as nitrogen stimulates stem and leaf growth).

I have a pretty perfect B1,B2,B3 and B6 vitamin pill (all apparently good for root growth), but it's got ginseng as its main ingredient, I wonder if plants like ginsenosides. ^^

^^^I was talking about these pots. They’re 14” deep.
https://www.groworganic.com/tree-growing-containers-treepots-tall.html

Okay, so I've been feeding 7 of my chili sprouts a not too old batch of B-vitamin pills. Just mashed one pill up and put it in water, and using a little bit at a time.

I started yesterday, applying it to the slow growing sprouts.

Google Drive Link

It's the one on the right that's fed B vitamins, and the one sprout in the middle-right of the left one, because it was growing a bit poorly. And the unsprouted, or hidden seed just below it.

So I will update this at least weekly. I will be using Imgur or something then, so I can show them directly.