Orchid Potting Media, What size chunks for what orchid?

[estación seca]

I want to go back and emphasize what Ray said. Orchid potting medium supports the roots. It should be chosen to ensure good air flow to the roots and that the roots have adequate water. The size chosen will also depend on ambient humidity. With large bark you can water every day. With finer bark, water will be retained longer.

[Fairorchids]

Emma,

All of the above information is correct, and incorrect. There are no absolutes, as the multiple variables are interrelated:

• Plant needs
• Environment (greenhouse/outdoors/indoors/etc.)
• Plant size
• Choice of pot (clay vs plastic vs basket)
• Choice of growing medium (or mix)
• The care you are able/willing to give your plants

When I get into a type of orchid, I often buy more than one of the same thing. For example, I have purchased Den kingianum from several sources:

J+L Orchids: Clay pot with all spaghnum moss.
SBOE: Plastic pot with granite pebbles
Dick Doran: Both clay & plastic, always bark/perlite mix
Exotic Orchids: Plastic pot with few large bark nuggets

Yet, I grow these plants successfully in smallish clay pots with a spaghnum/bark (2:1) mix.

Similarly, to suit my watering schedule, I grow my Cattleyas in many different combinations, depending upon plant size:

Plugs/small seedlings: Go into a 3" plastic pot with a chopped spaghnum/seedling size bark/charcoal/perlite mix (5:3:1:1)

Larger seedlings: 3.1/2" plastic pot, seedling size bark/charcoal/perlite mix (3:1:1)

Near blooming size: Clay pot, 4" or 5" azalea size, same mix, but 1/2 the bark is now 1/2" size nuggets.

Mature plants: Clay pot, 6" or 8" azalea size (bulb pan if larger diameter), same mix, but both bark & charcoal is now 1/2" size.

You need to make some choices for your conditions. Orchids will adjust to many treatments, but if a plant does not like what you are giving it, then change your mix or treatment.

You can use what the plant is in when you get it as some guidance, but keep in mind that plants grown in CA or HI are under conditions entirely different from what the rest of the country sees. In HI in particular, it rains so much, that plants are grown in much coarser mix than we can work with.

[emmajs243]

Hey guys! Amazing information! Loving the examples! Ok, I totally understand that you pick media based on root size and your environment, your watering tendencies, like so many of you have shown, the list really can go on!

I obviously got carried away and asked a pretty loaded question and should have just left it concise. And that is totally my fault....especially with the wording of "their types of medias" eh terrible choice of wording. Really sorry guys.

So to clarify, I was thinking maybe something like this...

Phals: I use a fir bark based mix, medium chips about 1/2-3/4" size. Sometime the large chips (3/4-1") if I want the plant to dry out quicker.

Catts, Cymbidiums,....: same fir bark based mix, only medium sized chips.

I am thinking main component of your media mixes whether it be as simple as I use sphagnum on seedlings under 2&1/2". OR, I prefer Orchiata bark vs others because....Or even...for me, adding medium size Perlite made a big difference primarily for my Phals because it.....increased air flow?

Broad advice basically. Or just a quick reason why you added one thing or another...If you moved tomorrow to a way different environment, would you completely throw out all of your media mix and start new? I wouldn't think so....I would imagine, even with a drastic environment change, your ratios might change, you might add or take away something but overall I would think there would be some things you would probably keep in your mix.

[emmajs243]

Fair Orchids! I am buying supplies to make my first, personal, potting mix right now! As much as I do really want to continue working with and testing s/h, I am not yet completely sold and have realized, its almost spring, I am going to have a lot of plants to repot, and s/h is going to take at least a few more months before I have a decision on if I want to try swapping over a few more plants....even still....When it comes to all my plants...I don't know how I feel about swapping over some of them like a plant that is in a 7 inch pot already....I feel like it would take such a larger toll the more established a plant is?

Anyways! My point, I need to have some regular potting mix handy! It just is silly that I don't yet! So I came back through and searched to find this post and a few others actually and I just have to say once again, your details and specifics, really helpful. Everyone really helped me overall understand kinda what to base your choice on but I am a tad too technical and you really helped by giving me a baseline for actual bark sizes and right now, I REALLY appreciate it! I have been trying to decide on a bark size for all too long now and your posts really helped!

I know all the variables the decision should be based on BUT, sometimes you just need a place to start from number wise! Knowing you use 1/2" bark for adult Cattleyas really helped me decide on what I wanted to try based on my environment and care habits!

[Fairorchids]

Emma,

You are welcome. A couple of other comments:

Every time you repot, you interrupt/disrupt the growth of the plant a little, so don't be in a rush to repot. Depending upon plant type/size/condition, I repot anywhere from every 18 to every 30-36 months. Of course, if a plant is declining in a new pot/medium, it may be necessary to change the mix again.

One key detail, regardless of mix you select, is that the plant needs to be firmly set (anchored) in the new mix. If it has poor roots:

• Use a rhizome clip for Cattleyas (clips to edge of pot, and straddles the rhizome).
• For Dendrobiums and other taller plants, push a short bamboo cane into the mix, to the bottom of the pot. Then tie the plant to this support, so it doesn't 'wobble' in the pot.

Lastly, I have a number of culture & repotting articles on my web site: Fair Orchids
Click on Orchids
Select Cultural notes