Information in common books or on the internet is not exact, it is borrowed from books on other plants, it is confusing and sometime contradictory, hereby we try to clarify all issues.
- Introduction – Why I know What I Know!
- What Is The Goal Of Repotting ?
- What Type and Size of Pot Is Best ?
- How Often Should I Repot My Plants ?
- How Do You Know When To Repot ? Re-potting to stimulate growth
- Conclusion ! – What You Should Keep In Mind When Repotting !
My Experience ! When I operated a retail nursery and tropical greenhouse I repotted thousands of plants and hundreds of different varieties of plants from cacti to large trees. The technique of transplanting remains basically the same for all plants. The only difference is the potting medium and how careful you need to be with the root structure. There are a few plants that do not want their roots disturbed at all and other plants that just don’t really care what you do to their roots. Marijuana is one of those plants that tolerates some root abuse.
Marijuana is just a weed that can grow just about anywhere in any kind of soil but not when you grow in pots, if you do not add dolomite you get a lot of problem. Learning the proper techniques will make an impact on your plant’s ability to grow properly. No, it won’t increase the THC content of your buds, but it will mean your plants will establish themselves quickly, becoming stronger faster. They will also grow better and bigger giving a better harvest.
It’s not rocket science and anybody can do it properly if taught the proper methods.
Do we transplant to get more nutrients to the plants roots? Yes, but that not the main reason, because we can give the plants liquid fertilizer. Do we transplant to make the plants grow larger? Well, larger plants are the result of transplanting, but that’s not why we repot plants. The real reason we re-pot plants is to give the plants more room to spread their roots. Marijuana plants love to spread out their roots. The faster they spread out their roots the faster they grow.
This is also the reason We Don’t Re-pot Flowering Cannabis Plants. There is no point ! When a marijuana plant is flowering, is not the time to try and take energy away from the flowers and grow roots. The plants growing is done and all it wants to do now is flower and produce the next generation. The time for re-potting was 4 to 8 weeks before going into the flowering room. If you think your flowering plant needs more nutrients, re-potting is not the way to go to accomplish the task. Use liquid organic fertilizers or compost teas at this stage instead of re-potting.
The main reason for re-potting is to add new soil properly amended with dolomite that would allow the grower to forget about the soil pH.
! What You Need to Know About pH, When Growing Marijuana in Soil !
The third reason is that the sophisticated grower can also vary the soil mix according to the age of the plant: more perlite and less nutrients for seedling, a richer soil with less perlite for the finishing pot.
The fourth reason that if you grow from clones indoor is the most important reason re-potting makes the clones shift from root-mode to grow-mode. [ This will be explained in details at at the end of this page]
Plastic pots are relatively inexpensive and worth the cost. I suggest black semi-rigid pot. These semi-rigid pots can be used over and over again for years. The hard plastic pots don’t last as long and become brittle over time.
- Never use a clear pot or a cutted plastic bottle as light can suppress root growth.
- Always make sure the growing container has drainage holes to prevent the soil from staying too moist and the plant from sitting in water.
- If you grow outdoor and it is hot, cover and insulate the pot to prevent cooking the roots. Roots always reach the container boundaries and the last thing you need is the container to reach high temperatures that cook and make the roots rotten.
A plant from seed or a clone should go in the small 1.4 liter pot, in order to save space and exploit the light to the maximum, this pot is 10 cm wide and 17 cm deep that is big enough for the root to expand for the next 30 days.
Then you can transplant is either the 3.4 liter or the 6.2 liter square pot depending on the varieties and on the plant size you desire i.e. you want to grow 16 plants: 4 x 4 3.4 liter pots or 9 plants: 3 x 3 6.2 liter pots.
Then only a big plant would need the last transplant in the finishing pot. The finishing pot, the pot the plant will stay in until harvest, should not be smaller then 6 liter but it can be as 200 liter it all depends on what plant you are growing: auto-flowering, indica or sativa and how your grow: indoor or outdoor.
Some growers will put their rooted clones straight into their finishing pots and that’s OK too, for expert grower.
Did you notice the shape of the small pot? This pot will prevent the plant from root-bound, if you are not using this kind of pot better re-pot one time more.
Re-pot One or Two Times ! There is no reason to re-pot a growing organic marijuana plant anymore than two times and in most cases only one time is enough.
Can I Over-pot a Marijuana Plant ? Yes ! It is possible to put a plant into a pot that is too big, but keep in mind the following.
It is fine even if it is not advisable to re-pot a seed plant in a big pot, do not over-water, increase watering as the plant increase in size.
Are you growing from clones? follow strictly the following guidelines !!!
A clone is always good to go into a 1.4 liter pot and later to go in the 3.4 liter but I don’t recommend going any larger at this stage unless you are an expert and even then I don’t recommend doing so.
The main problem is that it is easy to over-water over-potted plants. The small plant in a large pot is not able to use all the available water in the soil fast enough and this condition may actually begin to rot the roots. An over-watered plant goes into a permanent wilt with no hope of recovery. It may appear as a thirsty plant, but you know it isn’t thirsty because the soil is wet.
How can I tell if a plant needs re-potting ? There are no tell-tale signs that a plant needs re-potting. With marijuana it is easier re-pot accordingly to the plant size.
It is very easy to remember
A marijuana plant needs 1 gallon of soil for every 1 foot of growth or – if you prefer in metric units:
A marijuana plant needs 1liter of soil every 10cm of growth.
|Pot size||[ Ideal till ] Plant size|
|1.4 liter||15cm tall|
|3.4 liter||30-40cm tall|
|6.2 liter||60-70cm tall|
|9 liter||90-100cm tall|
When you grow from clones:
- check the roots and re-pot only when the clone is root-bound or nearly root-bound.
- do not transplant in a container that is too big
A plant grown from Seed behaves different from a plant grown from cuttings. The former grows while growing the roots, let’s say it is in grow-mode. The clone plant is in root-mode: when you made the cutting – in order to survive – the cutting cease to grow and develops only roots.
Then it will be the “power” of the sun that forces the plant to shift again to grow-mode.
But if you grow indoor what happens? There is no sun and the clone would stay in root-mode, it keeps developing only roots and it does not grow, leading to a disappointing harvest.
And while you “brake” your head finding the reason: you blame the quality of the clone, then you would come across some reasonable but wrong theories: for example there are articles speaking about the vitality and they say a clone has the age of the mother it is not as vital as a recently sprouted seedlings. It is all wrong: you only need to re-pot when the roots is well developed and you stimulate the cutting to return to growth.
- when the well developed root are in a bigger container they expand
- they hit – in 1,2 days – the container walls : there is no more room to grow roots
- the plant returns to grow instead of developing roots.
For the above reason, re-potting, according to the root development, is an effective way of stimulating growth. It is fundamental for clones and effective for seeds especially for Auto-flowering seeds. When you grow auto-flowering, there is little time and you need to maximize growth in order to maximize the harvest.
When growing auto-flowering: re-pot 3 times and each time you double the container volume. We suggest: 0.7liter cubic pot – 1.4 liter – 3.4 liter for the finishing pot.
Watch Jorge Cervantes making clones, transplanting at the right time, “pulling the neck out” of his clones and finally he re-pots: Watch the Video and Look at the small pot and look how tall are the clones! Moreover he is using yogurt cups and we just said not to use them, he is in Canada, nobody did get a sun burn in Canada
Conclusion ! – What You Should Keep In Mind When Repotting !
[ Optional for Seedlings, Very Important for Clones ]
|2nd Re-pot||3rd Re-pot
[ How big the plant? ]
|10 days when plants are 7-10cm tall||20-40 days when plants are 22-30cm tall||in the middle of the vegetative period|
How big the Pot?
|1.4 liter||3.4 or 6.2 liter||25-200 liter|
Repot always using the same or similar growing medium
|Re-pot clones at the right time or you will experience poor growth||Some growers do not fertilize after the 2nd, 3rd re-potting, they stop and they start again when they start flowering. Why?||Brake and loose the roots or the plant does not even realize it is in a bigger pot|
|Transplant in the same growing medium or similar medium|
|Do not water: the soil becomes heavy and it is very easy to damage the tiny roots.
Transplant just before watering and water after transplanting.
|It does not matter but It is more messy to re-pot if the soil is wet|
|Examine the roots, healty roots are white.
Smell the roots: healty roots do not smell, roots that begins to rotten smell.
Do not touch the roots they are so tiny and delicate, every time you touch them you are likely to cause damage.
|Grown Marijuana plants tolerates some sort of root abuse, it is better to to loose the roots and in case the plant is seriously root-bound: water before, let the roots soften and if they are too strong to be broken by hand, cut the the outside of the ball with a knife.|
The seedlings may be planted as deep as you like up to the first branch past the cotyledon leaves. However, most of the time you will only plant seedlings up to the cotyledon leaves as there will still be time to adjust the height at the next repotting.
Clones may be planted as deep as you like to adjust their heights to be the same. Cut off any of the clones branches that would be below the soil level when adjusting the height. All of the stem that is planted deeper into the soil will send out roots , making the plant sturdier and establishing it much quicker.
Do not expose the roots to strong light or wind
After transplanting, reduce light exposure: outdoor keep in shadow during the hottest hours, indoor reduce lighting time or rise the lamps.
Outdoor never let the sun to hit the black pots directly or it will cook the roots leading to roots rotting.
You do not need to sanitize the pots as long as you let them dry properly and you do not store them wet.
You do not need to fill the bottom of the pot with perlite or clay unless you can not empty the saucer after watering and you let the plants sit in water. Then add perlite to make the roots – always – sit above the water.
Why not fertilizing after the 2nd, 3rd transplant and resume in the flowering stage?
When growing indoor sometimes variety grow too much. If you do not fertilize they grow less and in the same time they develop a bigger root system because the roots expands looking for more nutrients. You save $$$ and in the same time you have a better plant.
It depends on which variety you are growing and only the experience can tell you if it is better this approach or the traditional approach.