Impact of bed/pot depth on pepper growth?

[mega]

I'm wondering if anyone has words of wisdom about what impact, if any, the depth of a garden bed, or a container, has on pepper growth. As opposed to width or total area available for root growth.

I have a variety of peppers in 5 gallon (11" deep) containers. Almost all of them are now 21-22 inches high. I also have a nice little garden bed, but the peppers are only 17-18 inches high, and a few are more like 14-15 ". The thing is, the bed gets more and better sun than the containers. AND, the bed has plenty of horizontal space for root growth. So I am thinking that the only explanation might be that the garden bed is only 7 inches deep before the roots hit hard clay, and that the roots ae hitting the clay and adjusting their expectations and plant growth accordingly, even though there is actually plenty of space for the roots to spread out horizontally if they so choose.

Does that make sense to anyone, or am I on a totally wrong track in figuring out what's wrong in the garden bed?

I'm also noticing that the plants in the beds are putting out many more blossoms than my deck plants - even though they are smaller and have far less well developed foliage. I have no idea why that would happen. Why would a SMALLER plant with LESS foliage put out more flowers?

 

[AjarnV]

IMO, 7" isn't much/enough. My large pots are 18"Dia. x 12"Dp.
I've got clay as well (when it's dry a pick axe is req.), so I've raised up my beds to about 15". These raised beds are not enclosed; I'm using the angle of repose to establish the boundaries. My first plants will go in the raised beds in about a month as I continue to bulk them up with humus.

When I was in the states I used lime to break up the clay; ever thought about doing that? It worked very well.

Edit: One thing to remember; the shape of a plant above ground is generally the shape of the root system underground. It's not 100% but worth a note.

 

[WickedMojo]

I have used a shallow bed before probably no more then 7"-8" deep but it was 8ft long and 4ft wide, the plants did great I think instead of growing down the root system just spreads out, I believe that as long as there's enough room either horizontally or vertically the plant will be fine, now in a container 7-8" deep is not enough because growth is also restricted by the sides of the container, but when you have several feet of horizontal space for the roots to expand then I dont see a problem with it, it may not be the prefered method because a deeper bed would be better, but its also not the worst thing you could do. hope this helps.

-Rich

 

[franzb69]

from what i've read pepper plants, tomato plants, and potato plants (they're all in the same family) have roots that spread outwards mostly and not downwards.

 

[Phadrus On Fire]

from what i've read pepper plants, tomato plants, and potato plants (they're all in the same family) have roots that spread outwards mostly and not downwards.

Dunno about that..

"pepper tap root depth"

First hit on google search: http://www.soilandhealth.org/01aglibrary/010137veg.roots/010137ch28.html

"Maturing Plants.--A final examination was made July 17. The plants were 20 inches high and for some time had been bearing fruit. The stalks were nearly 1 inch thick but the bushy tops did not cover the ground between the rows. Root development had kept pace with that of the tops. The strong laterals were 3 to 5 millimeters in diameter. Those that ran horizontally usually turned downward, 1 to 2 feet from their origin, and extended into the second or third foot of soil. The vertically and obliquely penetrating roots were usually deeper, a few reaching the 4-foot level."

Second hit on google search: http://www.fao.org/nr/water/cropinfo_pepper.html

"Root depth can extend up to 1 m but under irrigation roots are concentrated mainly in the upper 0.3m soil depth. Normally 100 percent of the water uptake occurs in the first 0.5 to 1.0 m soil depth"

While this indicates that the majority of water uptake is done by the shallower lateral root system, the tap root (and eventually the laterals will dig deeper too) can acutally extend a couple of feet down. If I'm not mistaken, tomatoes are the same way, in that they can have root systems that extend many feet into the subsoil. It all depends on the tilth of your soil though. There will not be much depth if you're planting in compacted sand or hard clay as the OP is. I think that you will have productive plants with the shallower roots, but they won't reach their maximum production because the deeper tap roots add stability to the plant so that it can support more branching and subsequently more pods.

 

[AjarnV]

from what i've read pepper plants, tomato plants, and potato plants (they're all in the same family) have roots that spread outwards mostly and not downwards.

Downwards is certainly a relative term; the roots on a mature nightshade plant definitely go deeper than 7". Less than 7" is not much of an anchor for a large plant of say 3 - 4 feet in height.

 

[AjarnV]

Dunno about that..

"pepper tap root depth"

First hit on google search: http://www.soilandhealth.org/01aglibrary/010137veg.roots/010137ch28.html

"Maturing Plants.--A final examination was made July 17. The plants were 20 inches high and for some time had been bearing fruit. The stalks were nearly 1 inch thick but the bushy tops did not cover the ground between the rows. Root development had kept pace with that of the tops. The strong laterals were 3 to 5 millimeters in diameter. Those that ran horizontally usually turned downward, 1 to 2 feet from their origin, and extended into the second or third foot of soil. The vertically and obliquely penetrating roots were usually deeper, a few reaching the 4-foot level."

Second hit on google search: http://www.fao.org/nr/water/cropinfo_pepper.html

"Root depth can extend up to 1 m but under irrigation roots are concentrated mainly in the upper 0.3m soil depth. Normally 100 percent of the water uptake occurs in the first 0.5 to 1.0 m soil depth"

While this indicates that the majority of water uptake is done by the shallower lateral root system, the tap root (and eventually the laterals will dig deeper too) can acutally extend a couple of feet down. If I'm not mistaken, tomatoes are the same way, in that they can have root systems that extend many feet into the subsoil. It all depends on the tilth of your soil though. There will not be much depth if you're planting in compacted sand or hard clay as the OP is. I think that you will have productive plants with the shallower roots, but they won't reach their maximum production because the deeper tap roots add stability to the plant so that it can support more branching and subsequently more pods.

+1 Excellent; I was composing as you posted. Nice research; I was going on my experience. Either way good job.

 

[AlabamaJack]

IMO for a first year plant a 5 gallon container which is about 11-13" deep is plenty...for a second year plant you will need more depth...

roots from most of my chinense grow out of the container into the ground by the end of the first year and my larger chinense get over 6' tall in a 5 gallon container...

I suppose what I am saying is that yes, depth has a lot to do with the size/production of a plant but you don't need that much depth for a first year plant IMO

 

[AcidRain23]

This may be helpful....
Here are some pics of pepper root development-

Young Plant:

1/2 grown:

Mature Plant:

From: http://www.soilandhealth.org/01aglibrary/010137veg.roots/010137ch28.html

 

[HawaiiAl]

Great post thanks. If you read The New SQ Foot Gardening book he stated most plants will grow and produce in 6" of his mix. I think its baloney, my raised beds are 10" deep and my plants do ok. I pulled some 2 year old plants they grew through the weed block way deeper.

 

[AjarnV]

Great post thanks. If you read The New SQ Foot Gardening book he stated most plants will grow and produce in 6" of his mix. I think its baloney, my raised beds are 10" deep and my plants do ok. I pulled some 2 year old plants they grew through the weed block way deeper.

Yup, that's why I'm raising my beds to 16-18". I expect my plants to grow below 18" eventually. LOL, my beds look like a dike, but not holding back water.

 

[mega]

original poster, here. Very useful replies and links, much appreciated. Those visuals of root development by age across depth and width are really interesting.

SFG: weird, the more I grow stuff, the less sold I am on some of those square foot gardening ideas (such as shallow beds, 1 foot distance between plants, etc). The soil mix seems to work well, but otherwise....not totally sold on it. Actually, even with the soil mix, I really question the 1/3 vermiculite idea as being excessive, imho.

 

[treemanjohn]

OP, AJ brought up a good point about a plants age. A first year plant will be perfectly happy in a 5 gallon container. I have backyard full of happy plants in buckets. I believe that your container plants are doing better because it's much easier to feed and water a container plant properly. Roots only have 2 purposes. They provide food and anchor the plant in the dirt. Plants don't have to seek nutrients as much when they're in containers

 

[HawaiiAl]

Mega= I read the book thought it was good, removed soil from raised bed 4' X 10' to the side. Added sqf garden mix to bed, planted 40 plants all died. took soil sample found soil acid level very high couldn't grow shit. removed 1/2 added old soil roto tilled to mix. ok now, planted 40 more plants all ok now. set me back 4 months. I try to learn some thing new all the time. though it was to good to be true IT WAS have been growing for 50 years think I would have known better. I do plant exery sq ft works good for me. have two raised beds 3' X 10' and 4' X 10' both have mac nut garden soil now.

 

[J762]

You said the ones in containers got less light than the ones in the ground. Is it a lot less light? They could have stretched in search of more light. Do they have the same number of nodes as the ones in ground, just spaced further apart? Are the leaves broader?

 

[franzb69]

nice diagram. now easily understood.