Originally Posted by aridbud
Very few plants in the plant kingdom spread laterally instead of vertically (depth). Plants (cannabis included) reach down deep to get their sustenance, water.
First off thanks to everyone for participating in the discussion!
From Hygrozyme Site:
There are predominately 2 main types of root systems: taproot and fibrous.
form a taproot system which consists of one main root, called the taproot. A taproot grows vertically into the growing medium and is usually deep-rooted. It is supported by smaller branch roots that grow from it.
form a fibrous root system and does not have a main root. The roots are thinner and grow closer to the surface of the growing medium.
Although cannabis plants are dicots, they can develop both root systems
Taproot Systems offer the best wind resistance, where Monocot
root systems are prone to being blown over.
Plants grown from clones form Monocot
fibrous root systems and do not have a taproot. This makes sense because clones need relatively high moisture and moderate warmth to root, which are conditions you would find in an equatorial forest with frequent rain.
Why waste time sending a tap root to search for water first if there is abundant rain water available close to the surface to use for growth immediately?
(lets not forget environment affects phenotype expression...meaning identical clones with the same dna (genotype) can express as totally different plants depending on environment)
Ive pruned off inner sucker branches from my plants in 12/12 and let them fall naturally on the soil surface of the pots and watered, surprised to find upright rooted clones growing all over around 7 days later on their own.
Imho i feel like the home environment (of the parent strains) has a massive influence on root system development.
Remember water takes the path of least resistance and likes to channel. similar to how taproots grow...
Landrace strains that grow in dry environments usually form long Dicot
taproot systems to chase water channels first, and landrace strains that grow in areas with frequent rains skip the water searching phase and form Monocot
shallow thick fibrous root systems to make use of as much water as possible ASAP focusing on growth immediately.
(^this also helps make sense why some people say clones grow faster)
From Silverback's Cannabis Root Systems icmag Thread:
Originally Posted by Silverback
There is virtually no tested information that I can find on cannabis root systems so I thought I would relay the anectdotal knowledge that I have learned about this aspect of OD cannabis growing.
Just a foreword, this topic can be very important to OD growers but is seldom considered when planning a grow. Those growing in containers can make a fatal decision to choose a strain with agressive roots or plant a full indica in a low lying area where their intolerace of excessive moisture around their roots is quickly observed. Some sativa's however, don't seem to have any concern at all with occasionally soaked soil. Knowing the characteristics of the roots can be very important.
Just as a general rule, most of the strains I have grown have had small to moderate root systems and I feel most strains probably fall into that category. By small, I mean they would easily fit into a 2-3 gallon container without really binding up. Moderate root development fits in about a 5 gallon bucket, even though they exceed the buckets width latterally, they easily fit if soil is removed.
There are certainly exceptions to these generalizations, and as many as there are strains I suspect.
100%-90% indicas and afghanis. - Although there are some big full indicas, many are compact with small root systems. Single colas, small statured branched plants under 4-5' dont have lots of weight to support ,dont suffer wind damage easily as they are not high profile and make great container plants and grow well outdoors in areas that don't have deep soil. I have one site where at 10" a clank is heard when one hits the solid rock shelf. These plants tolerate this condition well and grow without any problems there. Anytime big roots could be a problem, these are the strains to look at.
100%-90% Sativa's. - My experience with full sativas is less but I do believe that sativa root systems are somewhat dependent upon the point of origination of the native parent strains. I have come to believe that equatorial sativas have a wide snowshoe type of system but not necessarily a big tap root. Many don't have huge yields or weighty buds and even though they may grow tall, they don't offer much resistance to the eliments.
I think there is another group that originates further from the equator that shows variation in root systems depending on climate and rainfall and often do express a significant tap root. I know that Mexican sativa has a very different root system than columbian.
Hybrids: This category of plants have root systems that are all over the board and unfortunately, this is what many of us are growing. They range from KC-33 which has an agressive vigorous root sytem that can send a tap root to 4' and if it does blow over, roots just develop on the side of the root ball and the plant takes off again, contrasted against Early Riser, which has picked up an indica yield in the cross, but posseses a typical equatorial sativa root system that has difficulty supporting the heavy indica flower development that is wasnt intended to support and blows over in the wind easily and doesn't recover well.
Hybrid crosses can result in any combination of traits from the parents. While smaller statured hybrids still seem to have smaller root systems, there are some big yielding plants with small root systems that won't handle drought or wind, and some big strains with little yield with a deeper tap root than normal. There can be a lot of variation in root structure in the larger hybrids.
Generally, it seems to me that the biggest, deepest root systems come from hybrids where both parents were big and the growth is sativa dominated. These strains seem to have the wide lateral aspect from the sativa but the tap root that came with the big indica has also been hybridized and is exaggerated in size. It is impossible to know what kind of root development will be seen with mixed breeds such as 4 ways or crossed hybrids as they can recieve traits from any or all of the parents in the line.
I dig up roots as I use the same holes year after year. I think the lateral roots are probably there spreading out to the width of the plant or to the "drip line", just hairlike and not really visible. In fact, Ive seen some sativa strains that have a shallow, very fine mass of roots up to 4' in diameter but extending into the soil no more than a foot, with no real tap root at all. As far as your plants blowing over with yield weight, that may be a result of breeding/strain. You wouldn't believe the number of strains I have abandoned due to that one effect.
I think the greatest tap root size is seen in large, sativa dominated growth for an sativa/indica hybrid. Ive found these strains to have a wide variety of root systems from shallow and wide to deep rooted plants. I have often considered that soil conditions may have a great impact on the extensiveness of any root system simply because of the fact that when i plant a very big strain, the root system will be similar to the other large annual native weeds that grow around them and many of them extend well beyond 2' deep. I have one location in a river bottom that floods each winter and drops 6" of new sandy rich topsoil. The earth is black, soft and full of earthworms. Ive grown numerous strains in the area, but only those large sativa/indicas will thrive. Every other category blows over in the soft black dirt.
I don't think too many people grow big plants anymore. As i often grow in single plant sites, I find them advantageous to grow. They're different in a number of respects, including root systems.
I used to believe that variation was limited to large sativa/indica
hybrids but i grew 2 strains last year that had no tap root. None.
These were small statured indica's, but most cannabis i believe does have a tap root even if small.
Its really one of the reasons that i believe most growers would benefit greatly from finding a few strains they like and then comming to know the strain and its characteristics, rather than growing one unfamiliar strain after another. I have found it takes about 4-5 years of growing a strain to really learn how it will respond under any given condition and what its real attributes are.
Ive seen lots of variation in roots systems over the winter. The roots of the sour bubble i grew fillled up every inch of the pot, regardless of the size pot. The massive roots on sb dont transfer into plant health as sour bubble is weakish and freakish.
the joeys Sugarberry was a much larger plant than sour b, but had a much smaller root system and didnt crowd its containter at all.
I transplanted sensi star, white Rhino and Great white shark all on the same day, and a week later the shark roots were hanging out of the pot while the other 2 strains had no problems."
Originally Posted by neongreen
"Perhaps not the most huge of plants, but still a fair size (8ft and 9ft), these two Rombolts I grew in 2013 were in newly dug/amended beds that I had dug down to 4-5ft and removed any sizable stones from:
Here are the roots I dug up, and they only went down 1-1.5ft - no obvious primary tap-root to speak of.
I don't know why the roots wouldn't want to get bigger/go deeper for sure, but it could well be because they were all started in containers or because they were not allowed to get too dry (although I have always tried to keep watering to a minimum)."
Originally Posted by Mikell
Wish I had the article in easy reach, but most hemp research concludes that roughly 80% of the root mass will reside in the top 12 inches of soil. Re: supporting your observations, neon.
Originally Posted by wkalb
These weren't grown in large smart pots; 65 gallon pots have a 32" diameter. But thought this comparison might help someone.
super lemon haze I harvested last fall. Root ball mass was roughly 18" across. Small diameter feeder roots extended to the edge of the 65 gallon smart pot, but the bulk of the root ball was fairly unimpressive.
the panama Root ball mass extended most of the way to the edge of the 65 gallon smart pot (~28 inches). A bit more like what I expected, but still not as big as I imagined it would be.
SLH canopy was 5'-ish wide and the Panama was right at 4.5'.
The SLH yielded ~30% more than the Panama (with a root ball half the size), but that's likely just genetics (bushier plant, more bud sites?).
Originally Posted by Hoypare.
From Larry Stein, Ph.D, Extension Horticulturist, Department of Horticultural Sciences, Texas AgriLife Extension Service:
So What Constitutes An Effective Rain Event?
Mist, drizzle, fog; dreary, cloudy days, great for fruit tree chilling but does this wee bit of moisture associated with these events have any impact on agriculture? Well, it depends!; just what you wanted to hear!; as usual no cut and dried answer. The key to this dilemma lies in the amount of moisture which falls, the soil type and whether or not the soil is wet or dry. To answer this question we must examine the many, varied soil types.
Most soils are composed of varying amounts of sand, loam and clay. Soils with a lot of sand are called sandy soils and those with more clay are clay soils and of course there are many variations in between. The most ideal soil for most plants would be a sandy loam, as it takes and hold some water, but has ample oxygen as well. It is critical to remember that the only way plants can take up water is if there is oxygen present in the soil.[/b] Sands allows for rapid water infiltration, but they hold very little water. So typically sandy soils take in water, but hold very little and plants will dry out very quickly. Loams do not take water as fast as sands, but hold more water which can be used by plants for growth. Finally, clay soils take water slowly, so often a lot of water runs off in a heavy rain. Still even though such clay soils hold a lot of water, much of it cannot be extracted for plant growth.
The other soil factor which comes into play is the amount of rock as well as the depth of soil. Some of you have 6 inches of soil sitting on solid rock, others have less and then some have more. So if your soil is shallow, rocky and/or sandy, a small amount of water will penetrate further than on deeper soils.
To get a better understanding of water infiltration you have to know a little about soil physics. Soil physics tells one that soil must be totally wet before the water moves. So you cannot partially wet the soil, rather the water only penetrates as far as the water wets the soil. This should make sense because just a little bit of moisture (0.1 inches) will wet the soil on top and cause it to stick to your shoes, but go an inch deep and the soil will be bone dry.[/b]
Let’s examine some common infiltration rates for various soils.
Sands take in water faster than loams and clays, if the rainfall rate is 2 inches per hour, the sands will take in quite a bit of water whereas the loam and clay will not. So often times heavy, fast rain events are not effective at re-wetting the soil profile. In most cases much of this water runs off rather than in the soil.
By the same token one should realize that when the rain does not infiltrate the soil and runs off, the place of “ponding” will experience a much larger rain event. Bottomland is a prime example. Farmers today actually put small berms or dikes in their fields to increase water infiltration so that rain events will more effectively wet their soils.
The other thing you have to remember is how far an inch of water (from rain or a sprinkler, etc.) will wet the soil. One inch of water that does not run off will wet the soil 12 inches deep; but it will take more water to wet a loam, 1.5 to 2.0 inches and even more, 2.5 inches to wet a clay; and again this is assuming that no water runs off. The mist, drizzle and showers which often amount to a quarter of an inch or less obviously do not run off and so the water has wet into the soil, the only problem is that in most cases the soil is only wet a ½ to maybe an inch deep in most cases.
Since many areas have not received an inch of water in a long time, the soil profile has continued to dry. There is no question that your soil profile is dry. So if you have a foot of clay soil over rock, you will need to receive 2½ inches of rain where none of the water runs off to re-wet your soil.
The last factor to consider in water infiltration and an effective rain event is how wet the soil is. It should be obvious that a soil which has received a half inch irrigation is easier to wet than one which has not. A ½ inch watering will wet a sandy soil to about 6 inches. This means that only another ½ inch will be required to wet the soil to a foot. Calculations cannot be exact due to losses from evaporation. Still a soil which has been watered will benefit from a quarter to a half inch rain.
Lastly, the best time to water is actually during a rain event, of course if it is raining “cats and dogs” one would not want to water, because the water is already coming so fast that it will run off anyway. But mist and drizzle is a different story. No water will be evaporating since it is raining and the amount you apply along with the mist or drizzle will help wet the soil to a greater depth.
As many of the farmers have remarked, “I used to need a 2 inch rain, but 2 inches will no longer do it.” Rather we need a steady 4 inch rain where the water comes slowly to re-wet many of the different soils. If all we get is a cloud burst, the only places which will get any real benefit will be the places where the water ponds.
Grass is always greener closest to the highway because of water runoff from a hard surface. Perhaps you have noticed how the grass or weeds right beside paved roads or the overhang of buildings greens up in times of severe drought. This is again due to “runoff” of the water. The water does not penetrate the road and hence runs off. This ponding of a tenth or two results in at least a quarter or half inch rain beside the road. As a result the grass and weeds are able to grow. Notice that wildflowers come up and bloom ONLY next to roadways during droughts. Wildflowers can even get enough supplemental moisture from roadways to actually produce seed. The same is true of plants or trees beside the overhang of buildings. The water runs off the roof and is able to effectively wet soil sufficiently at the drip line of the building. So trees beside structures are able to survive better in their droughty times.
So it should be clear that the type and depth of soil along with the amount and speed of the rainfall event will determine just how effective the rain event is at re-wetting the soil profile. Mist and drizzle can be good at times, but in times of severe drought, it does very little.