Good morning Brick,
Thanks for helpful insight, as usual. I guess my question would be, Do we really want to use the same limited amount of medium for an entire grow?.
If you pick proper sized pots for what you will grow and how you will grow it you are not limiting or containing root growth.
As I mentioned I normally use 7-gallon pots though at times I will use 5-gallon pots. I failed to mention that is inside. I do not grow plants inside that are so tall and bushy that they need more than 7-gallons of soil to keep from having a crowded root-bound root structure.
Outside I use 15-gallon to 25-gallon pots.
Unless I misjudge the needs of a strain, and that has only happened a few times when I used 5-gallon pots, I never encounter the root-bound condition, and the few times it has been minimal. Most times using 5-gallon pots all of the soil will be used by roots, but not to a point approaching a root-bound condition. When I use the various larger pots, depending on if inside or outside and strain and veg time the most I will find at the deepest portions of the pots/soil are small roots that are no where near being crowded or tangled.There is no limitation involved.
Containing plants is not natural to begin with, as you mentioned our in-grounds have the entire planet to work with. So, here we are dumping water through this limited amount of soil over and over again during contained grows. Do we not lose a portion of our soil nutrients over time with this method, or am I missing something?. I like to give my ladies fresh soil to work with on occasion...is this a waste of time and $$?.
Consider the amount of space a plant's roots will use/spread to outside. How many times do you run water through it? How many times does it rain and more water passes through it? Did you happen to see the pictures of one plant grown outside, the monster plant that Nevil said the crop would be worth about $50,000.00 where he lives?
How do trees live hundreds of years without being given fresh soil periodically? You might ay their roots expand into fresh soil, but once a tree reaches it's full height/size it's roots do not continue to expand their range and spread into fresh soil. So for many years, or even decades or more, it survives in the exact same soil. While there is not a man made/artificial container plants, bushes and trees basically contain themselves within a certain amount of space. It is a more free-form shape than a container is, but the area used is not limitless. What is used is what is needed and using large pots to grow in you give plants the needed amount of space for roots.
How is it possible that the plant in the picture I posted could grow as it did and produce as well as it did? Natural soil, organics continually replenishing the soil and feeding the plant in conjunction with fertilizers and other nutrients being added to the soil, along of course with adequate moisture.
Growing in a pot is virtually the very same thing. If you provide adequate root space, which most growers do not do, and make sure that all nutritional needs are met then it is not as if you are growing in depleted soil and in need of fresh replacement soil. Places that sell high dollar designer soils will tell you that you should or need to replace the soil during a grow, but that is how they sell more soil and increase their profits.
Like most growers I used to start my plants out in small containers and up-can one, two or more times. But after seeing the performance of trees and bushes at our nursery, ones that were intended to be grow to large size. large caliper size, before being sold and that were started out in the size container they would be in when they would reach the size they would be sold at growing faster and being healthier than the other trees and bushes of the very same type that began in 1-gallon pots and were then up-canned to 3-gallon pots and then up-canned to 5-gallon pots and then up-canned to 7-gallon pots etc. etc. etc. I no longer saw a need to start plants in small containers and up-can.
There is less fuss and less mess and you eliminate the risk of damaging plants when re-potting and you eliminate any plant stress, even just short term, from re-potting. You don't use more soil, and if you are someone who likes to remove as much of the old soil as can safely be removed when re-potting you will use less soil in the long run so it keeps costs down. Some people claim that small plants in large containers risks root rot because the lower soil can be overly moist. Well, if you have short/small plants they have short/small roots so the roots are not down deep enough to be in what, if over watering is done, could be soil that is overly moist and could cause root rot. Also because of the moisture retention in the lower areas of the pots as the upper soil dries out through plant usage/transpiration, and evaporation moisture will wick up and plants are less likely to become over dry. The lower moisture will not wick up faster than the upper moisture is lost, so again, there is no danger of root rot.
There has been times when I has small plants and I needed to be away for a few days or so and normally my plants would need to be watered. I would water my plants as per usual and let the pots drain, but then fill the drip trays with water. I use somewhat deep drip trays so that put about 2 1/2 inches of water into the trays and the bottom 2 1/2 inches of the soil. If the roots were that deep it would cause an over watering situation and possible root rot. But since the roots were not that deep in the pots the highly saturated soil and water in the drip trays was not a problem. By the time I would get back home most or all the water from the drip trays would be gone. Some naturally evaporated, but some, along with the excess moisture in the lower soil, wicked up to replace the moisture that was used or lost in the upper part of the pots, where the plant's roots were, and I came home to happy perky plants.
I think the reason the belief that you need to start plants in small containers, sometimes party cups or even smaller containers, is because of what people see many ornamental plants in when they are sold. But consider the reasons why ornamentals are sold in flats of tiny containers. Most are greenhouse grown. The more plants you can fit per greenhouse the more plants you can sell. That means increased profits. If you are growing say 100,000 plants to be sold to Lowes and Wal-Mart etc. the smaller the container you can grow them in means you use less soil. That saves more money. When the plants are shipped more plants will fit on a truck making the per-plant shipping cost less, and that equates to saved money and increased profits. Part of what home gardeners like is to watch their plants grow. So smaller plants are more desirable than larger plants, when dealing with ornamental plants anyway, so it is senseless to grow and ship large plants in large containers to be sold.
So the true reasons behind starting plants in small containers is one of profit and not that they produce better healthier plants.
Have you ever noticed the late spring leftover flats or small pots of plants? Have you noticed how they are stretched, how they are spindly, how they are most times droopy, even shortly after being watered, how they can look sickly? They have outgrown their containers, they are root-bound. The small containers are only good for a limited period of time and after that they are harmful to plants. The plant's roots need lebensraum, living space, enough area to grow deeper and wider, to expand their range until they eventually reach their maximum size/range.
Just as the entire planet is never to large for even the smallest of plants to grow in, you can never use pots that are to large. But you can very easily, and most people do, use pots that are to small for fully healthy plants that will produce to their maximum capability. Even when people start with small containers and up-can they seldom end up using a large enough pot for their final finishing size. Unless someone's grow area/setup is such where there is a pot size limiting factor that will keep them from being able to use larger pots there is no valid reason to use undersized pots.
either way GL man hope i could help
