Plants have the uncanny ability to send their roots down and their shoots up, even if the seedlings are rotated. The plants are sensing gravity. But how? Ok, so I have had success putting them root down.. its what I have always done. Im no expert but ive grown a couple times with shitty grow rooms, and they… Hi Nico, Quick question: Should I germinate my seeds before planting? If so, what's the best way to do it? Thanks, Cori W. Hi Cori, thank you for writing
How Do Plants Know Which Way Is Up And Which Way Is Down?
It’s dark down there in the potting soil. There’s no light, no sunshine. So how does it know which way is up and which way is down? It does know. Seeds routinely send shoots up toward the sky, and roots the other way. Darkness doesn’t confuse them. Somehow, they get it right.
More intriguing, if you turn a seedling (or a whole bunch of seedlings) upside down, as Thomas Andrew Knight of the British Royal Society did around 200 years ago, the tips and roots of the plant will sense, “Hey, I’m upside down,” and will wiggle their way to the right direction, doing a double U-turn, like this:
How do they know? According to botanist Daniel Chamovitz, Thomas Knight 200 years ago assumed that plants must sense gravity. They feel the pull of the Earth. Knight proved it with a crazy experiment involving a spinning plate.
He attached a bunch of plant seedlings onto a disc (think of a 78 rpm record made of wood). The plate was then turned by a water wheel powered by a local stream, “at a nauseating speed of 150 revolutions per minute for several days.”
If you’ve ever been at amusement park in a spinning tea cup, you know that because of centrifugal force you get pushed away from the center of the spinning object toward the outside.
Knight wondered, would the plants respond to the centrifugal pull of gravity and point their roots to the outside of the spinning plate? When he looked.
. that’s what they’d done. Every plant on the disc had responded to the pull of gravity, and pointed its roots to the outside. The roots pointed out, the shoots pointed in. So Thomas Knight proved that plants can and do sense gravitational pull.
But he couldn’t explain how.
We humans have teeny crystalline stones floating in our ear cavities that literally sink in response to gravity, telling us what’s up and what’s down. What do plants have?
Strangely, this is a real puzzle. We still don’t know for sure how plants do it. There is a team of botanists, John Kiss and his colleagues at Miami University in Ohio, who have a promising idea, but at the moment it’s just a very educated guess.
Plants have special cells right down at the tip — the very bottom — of their roots. And if you look closely, inside these cells there are dense, little ball like structures called “statoliths” which comes from the Greek, meaning “stationary stone.” You can see them here.
I think of them as pebbles inside a jar. If the jar is upright, the pebbles, naturally, fall to the bottom.
If I put the jar on its side, the pebbles will roll to the side of the jar, the new bottom, and lie there.
If I turn the jar upside down, the pebbles will drop into the cap, which used to be the top but is now the bottom.
Basically these little pebbly things respond to gravity. In a plant cell, gravity pulls them to the “bottom,” and once they find a resting place, they can send signals to neighboring cells in the plant essentially saying, “OK guys! We now know where Down is. Those of you that need to go down (root cells), go this way! Those of you who need to go up (the shoot on top), go the other way!”
This, suggests Professor Kiss, is how plants figure out where “down” is. They use little statolith balls as gravity receptors.
His idea got a boost when he sent some seedlings into space (to the space station) where the pull of gravity is close to zero, figuring if the statoliths just float randomly and don’t drop to the bottom of their cells, the plants won’t know which way is down. And sure enough, he reported that plants growing in space did not send their roots in any specific direction. The roots just went every which way.
So the next time you pass a tree, a flower, a grape vine, grasses, bushes, vegetables any plant that seems to be reaching for the sky, that plant may be going up not just because it wants to be kissed by the sun, but also because down at its bottom, in cells rooted in the Earth, it’s got itty bitty rocks telling it, “go thattaway!”
Daniel Chamovitz’s account of how plants tell up from down comes from his new book, What A Plant Knows: A Field Guide to the Senses. The drawings are my own, and are based on Professor Chamovitz’s descriptions. If there’s something wrong with them, the fault is mine, not his.
Putting seeds in soil , root up , root down.
Ok, so I have had success putting them root down.. its what I have always done. Im no expert but ive grown a couple times with shitty grow rooms, and they have always come outta the ground. But, I was reading a post the other day that said to put it root UP, because the root curls , and it will only have to curl once to make its way down. So instead of having the root down , where it wastes energy curling twice, once towards to “top” of the seed casing, and then down again to the bottom of the pot. u put it root up so it only curls once, downward.
Im starting to think its true, because after looking closely at a germinating seed, it down infact look like its curling towards the “top” of the seed casing.
I soak my seeds in water and just throw them any way they land on the soil and cover them. It is good to put the root down.
I soak my seeds in water and just throw them any way they land on the soil and cover them. It is good to put the root down.
thats what everyone says. And also what I believed. But after reading about it , and actually looking at a seed when the root is first coming out. It does look like the seed should be placed root up , as the root looks like its curling down like the post I looked at said.
Dunno , i never put em in exactly perfect anyway. Anything will work really.
I see what ya mean about the root curling. I just looked at my sprouts before coming to where i have internet service. When i go home im going to check that out. Mine always grow as well. Interesting thought.
smoky mac pot
I used to put them root down. Then read somewhere to put them root up and have been doing it that way since. I think it works better. Makes more sense to me anyway.
Yea on my first grow i planted root up and they sprouted in less than 1 day. Now this is my second grow and i planted root down and they still havent sprouted and its been 3 days so now im worried
A CUT and PASTE for you all I have read ssen and heard of both up and down
Marijuana seeds should be placed with the POINTED END UP into a prepared cannabis seeds germination bed or just good soil at a depth of 1/2 to 3/4 inch. The embryo tap root emerges from the pointed (stylar) end and the natural method of growth is for this root to make a turn and grow downward (see the illustration) This bend formed by the downward curve of the taproot is what emerges from the soil and the friction of dragging the cannabis seeds upward helps the new plant to loosen and cast off the seed case when it breaks through the surface. If the cannabis seeds are placed with the pointed end down, the embryo will be required to expend a great deal of its stored energy for twisting and turning to position the tap root when it realizes that it is heading the wrong way (see illustration of germinating marijuana seeds) The seedling will need this energy to exert the forces required to later lift its head (now enclosed by the two halves of the seed case) above the soil, cast off the seed case and then spread its two embryo leaves and begin the life-giving photosynthetic process. This is a critical stage in growth and carelessness in placing the marijuana seeds will exhaust even the most hearty seedling and result in a slow start and a feeble plant in later life. Cannabis seeds should be placed in a small hole at a depth of 1/2 to 3/4 inch. An excellent medium for germination is a mixture of rich humus and fine sand, such as the type used for aquariums. The soil needs a ph of 7.5 to 8.0 and should not be so moist that it sticks to your fingers. If the medium is too moist, the seeds will rot and ferment before they can sprout. A simple test for moisture is to stick a pencil into the soil and if soil adheres to it when removed, then it is too moist. Sort of like when you test a cake by sticking a straw into it to see if it is baked through to the middle. The ideal is not too moist, and not too dry – and be sure that the soil is well-drained. Research has shown that a soil temperature that is at, or slightly above, the air temperature promotes the best survival rates and growth.
My question is in the wild when plants drop their seeds do the drop them point up or point down think about it
im not sure it really matters it has to work harder one way then the other but it would only seperate men for boys or should i say girls from woman
I’m new to growing and i purchased some seeds from a website. My plants are about 2 weeks now and they are about 8 inches tall with the four leaves. I think they are on pace, what sort of things should i do to improve growing at this point? I have them under a hp gro light 24 hours a day. Also what new stages should I be looking for to know their healthy?
Seed Germination & Planting
Hi Cori, thank you for writing us! Your question is pretty simple to answer, but sometimes not so simple to do! In short, yes, most growers tend to germinate seeds before planting them into their grow medium of choice.
To be clear, however, germination of seeds is not necessary prior to planting in medium. You can sow seeds directly into the medium and they will also germinate there, but not always with the same success rate. The reason growers choose to germinate outside the grow medium is because it is easier to control the conditions surrounding the seeds. This leads to the second part of your question, which is the best-case practices for germinating seeds – this leads to the harder answers.
There are many different ways to germinate seeds. Probably the best methods involve keeping the practice as natural as possible. The simplest methods use water, warmth and darkness – all conditions the seed would naturally encounter underground. Many folks simply lay some seeds down on a paper towel on a flat plate, cover them with another paper towel, then moisten the paper and place the plate in a warm dark place. A popular hiding spot has always been on top of the refrigerator, while more professional growers employ heat mats that lie flat beneath seedling/ clone trays. Heat mats are an excellent and inexpensive aid for seed germination. Whatever you decide, the temperature should be 10-20 degrees above room temperature, or range between 78 – 90F.
Of course, there are always the tricky strains or the old seeds that are quite fussy and refuse to pop. These seeds require a bit more attention and creativity. Some people prefer to soak the seeds for a short period before placing them in a moist and warm place for germinating. Some people go as far as to use mild chemical solutions to help soften the shell and prod the seeds. Other growers will even use very sharp and sterile razors to carefully slice seed shells or tips to help induce germination. These practices are all risky and should only be used as a last resort.
Once a seed cracks open, the taproot appears. This taproot will become the plants primary root from which all other roots will grow. Technically, the seed is germinated once you can see the white of the taproot. Some grows prefer to wait until the taproot is 1-2 cm long before planting the germinated seed into a medium. Once you are ready to do so, be sure to place the seed about a half-inch below the surface of the medium with the taproot point downward and the seed shell on top. Be sure there is some space for the seed shell to push upwards through the medium, towards the light. At this point, the very young seedling still needs moisture, warmth and a bit of light now to direct its growth in the right direction. The seedling will likely be in this medium and container for a few more weeks before the seedling is ready to be transplanted into a larger container for vegetation.
Thanks for reading everyone and remember: Grow… And help the world grow, too!