Do roots grow out more or down more?

I have a hypothesis curious what everyone else says.

I know most people says make the holes 3x3 or 2x2. how deep does everyone dig? judging from my indoor experience i feel like MJ is a shallow rooter and likes to grow roots outward. That begs the question should i only dig a foot down and out 4x4? or do a 2x2 and dig 2ft down? Let the fun begin.

Both. They push down for water/nutrition/stability, and outward for all the same reasons.

If you want a monster plant, dig a monster hole with additional compost at the bottom. And if not, downsize accordingly.

I tend to go slightly deeper than wider. Feel like I get better water retention that way since it's cooler down there.

Here's what guides me: My mom was a botanist and everything in her garden was amazing. Her rule was "dig a $100 hole for a $10 plant".

Sorry, forgot to say in Ed Rosenthal's Marijuana Grower's Handbook, he explains plants from seed have tap roots, and clones have that spidery thin root mass. Haven't started a seed and planted it in the ground yet, but would tend to go deeper than wider for seed started plants based on that and closer to equal for clones. Bigger the hole, bigger the plant.

Depends on your plant and the soil. Generally roots will go down about a foot or two, expanding outwards while they are doing it. If the soil starts to get more dense they'll expand out. If your soil is light enough and roots are constrained from growing outwards, the roots will grow down further.

In optimal conditions they will grow out a little further than down in my experience. More so with clones than seeds, but true in both instances.

Also keep in mind that tap roots will not always grow strait down. Even without lower constraints they will some times curl a bit or end up growing sideways. They try to grow strait down, but don't always end up producing that result.

pretty much anything deeper then 18" is a waste of time IMO. I dug my rows 2-2 1/2feet deep when I did the big rows on the big 40 grow. The rows were 10 feet wide. When I removed the plants, the roots were not in the bottom of the rows at all. 18 " or so is about as deep as they ran. Now what Dan saiid is true, depends on soil conditions, but most soil mixes we use, 18 " is all I'm seeing. They took every bit of that 10 foot width though, and they ran their roots together the other way, so they went far to the sides. So, digging a 10 ft deep hole on other words is a waste!

I've been digging approximately 2' diameter holes by about 2 1/2' deep and fill with promix. The roots tear through it both vertically and laterally. I started going slightly deeper because I was seeing a trend that the last 6" or so had much better moisture retention and stayed cool to the touch, even though there was still plenty of root mass down there.

Plant roots mainly expand outwards. They explore the subsoil, but don't depend on it for nutrition, more as a water reserve.

Under 18", there isin't much going on.

Regardless, dig a big ass hole, then when you think you're done, make it bigger.

i was looking for confirmation about this topic as well. good info. I didnt want to do unnessary work. Since the water level is about 16" so i was hopping it woldnt kill my plants and i didnt need to worry about watering all summer.

I've grown plants in full size garbage cans and still had them rootbound at the bottom.

Dan Kone said:

I've grown plants in full size garbage cans and still had them rootbound at the bottom.

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but they didnt have any choice but to grow down... I think i agree w/ most between 20-15 inches deep is about the most they would want to go outside. i think i will make the hole 3x3 15in deep but also loosen all the soil around the hole another 2ft out. Hauling in soil is going to be a chore

wheezer said:

pretty much anything deeper then 18" is a waste of time IMO. I dug my rows 2-2 1/2feet deep when I did the big rows on the big 40 grow. The rows were 10 feet wide. When I removed the plants, the roots were not in the bottom of the rows at all. 18 " or so is about as deep as they ran. Now what Dan saiid is true, depends on soil conditions, but most soil mixes we use, 18 " is all I'm seeing. They took every bit of that 10 foot width though, and they ran their roots together the other way, so they went far to the sides. So, digging a 10 ft deep hole on other words is a waste!

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Wheezer your one hell of a gardener so I'm inclined to go with your opinion based on the evidence you presented. That's a pretty good example if you ask me. I saw that grow and It looked like if those robust plants of yours wanted to go south they would have. Having exhibited the opposite I think is very compelling indeed. If I end up growing in the dirt I will till my soil for shallow roots and plan on going wide. Thanks for the post.

Dan Kone said:

I've grown plants in full size garbage cans and still had them rootbound at the bottom.

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DK, I hear what your saying but I don't think it's the same. What I saw in Wheezers grow was the unrestricted access to either deep or wide and the plants when presented with the option chose wide. Although come to think of it that could have been caused by frequent light waterings so mayby I'm wrong.
Hey Wheezer, did ya water long and deep or frequent and shallow?

outdoorfresh said:

i was looking for confirmation about this topic as well. good info. I didnt want to do unnessary work. Since the water level is about 16" so i was hopping it woldnt kill my plants and i didnt need to worry about watering all summer.

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The fluctuation from spring to middle of summer will be wxtreme though No? We have surface water in spring snowmelt but then dry as a bone in summer.
Is yours different than ours? Water table I mean! We have to make a mound to plant trees because if the roots go deep and the water rises it's sayanarra baby!!

powerslide said:

but they didnt have any choice but to grow down... I think i agree w/ most between 20-15 inches deep is about the most they would want to go outside. i think i will make the hole 3x3 15in deep but also loosen all the soil around the hole another 2ft out. Hauling in soil is going to be a chore

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Correct. As long as you give roots plenty of room to grow out, it's unnecessary to make holes deeper than 2 feet.

I'm just saying, roots can grow deeper than that under certain conditions.

root masses form a ball.........one cubic foot is enough to grow a cannabis plant 14 feet tall. if allowed, a plant will send a longer tap root downward, but not necessary.

scroglodyte said:

root masses form a ball.........one cubic foot is enough to grow a cannabis plant 14 feet tall.

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That's not very realistic. I suppose it's possible, but unlikely and would be a pain in the ass to deal with. 1cu foot is about a 3 gallon pot right? Yeah, I'm not sure about that. You really don't want anything bigger than ~3-4 feet max in a pot that size. Even then, you'll be feeding it every day.

it all bepends on your drainage. just like air pots. if the soil drys out in the top 3 inchs fast those roots will die leaving the roots below. and if you get a drought then it will be farther down training them to go deep. you want soil to be moist taking 3 days to dry oout. othere wise the only roots your going to have are the roots that are below this dry zone training them to go down looking for the water. i plant in all kinds of soil amendeing it to my loctaions. some places get alot of water. and i take 4cudic foot bags of perlit in to fix it. others are rocks and gravel and i goota take straw in to mulch to keep the ground wet. and some are swampy i make raised beds. its the air that will make the roots take there shape. you can tell in your area look for blown over trees you only see this in swampy areas where the roots grow out and not down. if its not swampy youll see trees snaped off.