Pot size, growth rate question

[Rid]

I keep reading that an orchid should be potted to allow 2 years of growth. How much would an average size Cattleya or oncidium grown in that time frame? Mine are outside in the humid southeast.

[ArronOB]

In your climate, for the cattleyas imagine two new pseudobulbs (with leaf/s) per growing lead per annum, and each new pseudobulb being about 30% larger then the one before.

Just a rough figure, but necessarily so.

[Swimmingorchids]

growth is snailpace slow. I am watching a new flower spike grow at the moment. We're at a finger length after a month

The 2 year rule is not necessarily because the orchid will have outgrown its pot - it is because most orchid mediums break down and start to rot after 2 years.

So unless you have gone 100% hydroponic you should aim to replace the bark/spagnum/coco mix or whatever after 2 years

[Ray]

What you "keep reading" is an oversimplified generalization. Just about everything documented in books or online is an individual's observation - of their plants in their growing conditions - and neither the teller nor the reader bothers to consider that what is being related might not be applicable to another individual's situation.

There are multiple reasons for not going overboard on the pot size.

1. Media breakdown rate might be one, but "2 years" by itself is ridiculous, as each material, or even the same material from a different source, might have different practical life spans. Plus, two individuals using the very same medium, will likely have entirely different experiences.
2. Under my conditions and with the plants i grow, my orchids do not grow at a "snail's pace"; some are much faster (I have paphs and phrags that put out a half-dozen growths in a year, sometimes more) and another (Paph stonei) that has put on two growths in 4 years. I have phalaenopsis that stay in 3" pots, while others outgrow 12" pots.
3. Some plants seem to view mechanical stability in the pot as a crucial factor, so must practically fill the pot with roots before you see any shoot growth, while others are apparently fine with being overpotted, and just carry on as if nothing had happened.
4. If you use an inert, inorganic medium, even though it won't decompose, it will still accumulate mineral residues, plant wastes, and biological buildup that can combine to create a toxic environment for the plant.

So you, as an individual, must take all of these factors into account and find the right strategy that works to the maximum benefit of your plants under your growing conditions and with your inclination to "mess with" your plant or not.

I know a commercial grower in central Pennsylvania who has some of the best plants, and lots of awards, and he repots every plant annually.

I use a lot of LECA, yet my plants get repotted every 2-3 years. I have a phrag that was moved from a 6" pot to a 10" pot last summer, and I need to unpot it and divide it this summer.

[Swimmingorchids]

I am relatively new to growing orchids and to me they do grow at a snails pace. I had to trim off a wheelbarrow of branches off my currant bushes this month.

Your argument is that your fastest growing plant can produce 6 growths per year or 1 every 2 months.

Don't get me wrong, I am fascinated by these magnificent plants but they grow at a snails pace lol

[Ray]

Originally Posted by Swimmingorchids

I am relatively new to growing orchids and to me they do grow at a snails pace. I had to trim off a wheelbarrow of branches off my currant bushes this month.

Your argument is that your fastest growing plant can produce 6 growths per year or 1 every 2 months.

Don't get me wrong, I am fascinated by these magnificent plants but they grow at a snails pace lol

I have no disagreement that most orchids are slow-growers. My comment was meant to counter your stance that they all are like that.

You have made an erroneous assumption: 6 growths in a year does not mean one every two months. If only!

After 45+ years of growing orchids, I typically expect a paph growth to reach maturity and blooming in 9 months to a year, but as my culture improved, I've seen that sometimes cut to 6-7 months. For years, my paphiopedilum culture typically resulted in a single growth at a time, now it has improved to see multiples emerging in short order.

I do have some bollea/pescatorea/warcewiczella-complex hybrids whose growths can go from emergence to blooming in two months, but that is a rarity, and varies from plant to plant within any hybrid.