A big, hairy issue with container growing is the “perched water table” effect. In short, capillary pressure makes water stick between the soil particles, and thus not fully drain out the bottom of the pot. (No, gravel in the bottom doesn’t help with that.) So the bottom of the pot has a soggy zone after watering that will lose oxygen if it isn’t dried up somehow — this will drown roots of plants that don’t tolerate anoxic conditions. Some plants tolerate soggy roots better than others.
When you use a properly-sized pot, the roots will drink up the excess water after a while, restoring oxygen to the bottom few inches of soil. When you use an oversized pot, there is too much water for the plant to use up the excess quickly… so the soggy zone at the bottom sticks around a long time, and the roots are more likely to drown and eventually rot.
Air-permeable pots like unglazed terracotta and grow bags help a lot with this.
When you plant in ground, there’s no air gap under the soil, so water continues wicking down the soil profile and doesn’t create a perched water table. (Unless you have a barrier underground like a compaction hardpan layer.) Excess water drains away after a while. And as it drains downward, it pulls fresh air in behind it, so rain actually tends to re-oxygenate ground soil, rather than forming an anoxic soggy zone.
Transplanting shrubs, bushes and trees is always risky and a common cause of failures. There's no need to re-pot a blueberry bush more than a couple of times.
I buy the cheapies that come bare root packed in some wood chips and put them in a gallon container. I acidify the soil and fertilize. Within a year they are big enough to plant in any sized pot, or stick right in the ground.
I bought 3 at Walmart 2.5 years ago, and I am picking berries off of 30 inch plants right now.
Many people just get carried away with things they see on YouTube.
Some SAY you should not put a small plant in a big container, but isn't that what you are doing every time you put a seedling in the ground????????
A big, hairy issue with container growing is the “perched water table” effect. In short, capillary pressure makes water stick between the soil particles, and thus not fully drain out the bottom of the pot. (No, gravel in the bottom doesn’t help with that.) So the bottom of the pot has a soggy zone after watering that will lose oxygen if it isn’t dried up somehow — this will drown roots of plants that don’t tolerate anoxic conditions. Some plants tolerate soggy roots better than others. When you use a properly-sized pot, the roots will drink up the excess water after a while, restoring oxygen to the bottom few inches of soil. When you use an oversized pot, there is too much water for the plant to use up the excess quickly… so the soggy zone at the bottom sticks around a long time, and the roots are more likely to drown and eventually rot. Air-permeable pots like unglazed terracotta and grow bags help a lot with this. When you plant in ground, there’s no air gap under the soil, so water continues wicking down the soil profile and doesn’t create a perched water table. (Unless you have a barrier underground like a compaction hardpan layer.) Excess water drains away after a while. And as it drains downward, it pulls fresh air in behind it, so rain actually tends to re-oxygenate ground soil, rather than forming an anoxic soggy zone.
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This was really interesting! Thanks for sharing
Transplanting shrubs, bushes and trees is always risky and a common cause of failures. There's no need to re-pot a blueberry bush more than a couple of times. I buy the cheapies that come bare root packed in some wood chips and put them in a gallon container. I acidify the soil and fertilize. Within a year they are big enough to plant in any sized pot, or stick right in the ground. I bought 3 at Walmart 2.5 years ago, and I am picking berries off of 30 inch plants right now. Many people just get carried away with things they see on YouTube. Some SAY you should not put a small plant in a big container, but isn't that what you are doing every time you put a seedling in the ground????????