Beginner Gardening: Advice for repotting a baby Schefflera, 1 by tapla

tapla wrote:
1) People who are used to using heavy soils will tell you that you need to be careful about over-potting, and you should move up in pot size gradually. When it comes to trees, and plants with roots similar to tree roots, you really need to be thinking about tending to the roots, as well. Once the roots of a plant become congested, growth will always be inhibited, no matter how large a pot you pot up into, unless/until you correct the root issues by selective pruning (of the roots).

I wrote this about container size relations for another forum several years ago. It explains the relationship between plant material (size), pot size, and soil choice:

"Over-potting" is a term that arises from a lack of basic knowledge about the 3-way relationship between plant material/ soil composition/ container size, which together logically determine appropriate container size(s).
It's often parroted that you should only move up 1 size in containers when "potting-up". The reasoning is that the soil will remain wet too long and cause root rot issues. Of course, that's true if you're growing in a heavy, inappropriate soil, but it can be remedied by changing the soil to one that drains freely.

The size/mass of the material and soil type/composition determine both the upper & lower limits of appropriate container size. Plants grown in slow soils need to be grown in containers with smaller soil volumes so that the plant can use water quickly, allowing air to return to the soil. This (smaller soil volumes) will cause plants to both extend branches and gain o/a mass much more slowly. Rampant growth can be had by growing in very large containers and in very fast soils where frequent watering and fertilizing is required - so it's not that trees necessarily rebel at being potted into very large containers per se, but rather, they rebel at being potted into very large containers with a soil that is too slow.

We know that there is an inverse relationship between soil particle size and the height of the PWT in containers. As particle size increases, the height of the PWT decreases, until at about a particle size of just under 1/8 inch, soils will no longer hold perched water. If there is no perched water, the soil is ALWAYS well aerated, even when the soil is at container capacity (saturated).

If you wish to grow in a large container - please do. Just be certain that your soil supports no, or very little perched water. You have all the tools you need to make an excellent soil. Now all you need is the confidence and the materials. ;o)

The short answer to your question is: Whether or not it is appropriate to plant in the considerably larger container depends entirely on your choice of soil. It is probably inappropriately large if you are using a slow/heavy soil, but perfectly suitable if your soil drains freely and is well-aerated.

2) You don't need a special soil, but using an appropriate soil will make your (plant tending) job a lot more fun and make it easier to grow plants with superior vitality. It also can provide you with a much wider margin for error in your approach to growing in containers - makes things more fool-proof.

3) It doesn't matter if you leave them as they are, or space them more widely.

The plant appreciates full sun. If you only pot up, it's ok to do so now, but I would encourage you to do a full repot, which includes root pruning when you repot your planting. Doing THAT would be more appropriate in mid-late June.

Al