Potting Medium

[Markedg]

Hi All, I live in Dublin, Ireland and I have been growing orchids for awhile. I was born in the US and grew orchids, esp. paphs under lights with no problem. After 17 years living in Ireland, I finally had a 10'x12' greenhouse built a few years ago. I have a mixed collection, paphs, a few phrags, cattleyas, dendrobiums and most of them are doing well and flowering. I have 60% shade cloth, electric heat and a humidifogger which keeps the humidity at 70% or so.

I like paphs, especially the multiflorals and brachys and I have gotten most of them from Sam Tsui of Orchid Inn on one of his trips to Europe. I have them potted in a medium bark and perlite in equal quantities. Now here are my queries. The multiflorals leaves are a very light green(this may be a bit too much light) and are doing well(for the most part). One of them, on one of the oldest leaf, started to go brown from the tip to the crown, it was dry and not wet and I promptly removed the leaf. I have read that this could be due to over fertilising but I only feed seldom and I have not done that so far this year. I have a few phrags and I know that if this happens with these, it is not enough water. Could this browning be due to not enough or too much water in the medium? Fine bark is a bit hard to get in Ireland and the shipping costs from the UK would be prohibitive. In regards a good potting medium, would just the straight medium bark be okay? or should I adding something else? I would like to be able to keep them moist without overwatering so I don't rot the roots. I tend to water 1x a week in summer and maybe every 2 weeks in winter. Sorry about the long post and I do appreciate any help you can give me.

 

[goldenrose]

Hi Markedg, Welcome to the forum!
IMO the brachys should do fine with your current mix. The multis on the other hand probably would do better with less perlite. They tend to like water in the summer months and could be drying out too much in between waterings. Do you double water when you do water? (Water everything once & then go back & do it again).
You haven't mentioned pot sizes, which could make quite a difference.
We're 5 months into the year, at what point would you fertilize? If anything you're underfertilizing but if the potting media isn't wet/moist when you fertilize you can burn roots.

 

[Markedg]

Thanks Goldenrose. I think the problem is not enough water on the multis and they are drying too much. I am a bit afraid of watering too much and causing root rot. I will repot the multis into straight bark with just a little perlite. The pots are not that big, 3 or 4". I use rain water and I have heard that some fertilizers can change the ph of the rain water due to lack of any buffering and this could cause more issues. There is a nursery In Belgium that sells something very similar to MSU and that it is for rain/pure water.

 

[NYEric]

Welcome from NYC!
If you are having trouble w/ chlorophyl you can add a little magnesium to your fertilization thru epsom salts to green the leaves up. You can add a moisture retaining media like sphagnum or diatomite if the media is too dry. Good luck.

 

[goldenrose]

Thanks Goldenrose. I think the problem is not enough water on the multis and they are drying too much. I am a bit afraid of watering too much and causing root rot...

If you're afraid of overwatering, leave your 50/50 mix but water 2x a week, you've got good drainage with that proportion, I can't imagine that there would be any problem! Some multis come from tropic areas where they'd never really dry out, constant moisture, good air movement & good drainage!
and as Eric mentioned, can't go wrong with epsom salts!

 

[SlipperFan]

Welcome, Markedg! Choosing the right media for plants is an on-going experiment for me. I'm always learning...

 

[Paul]

Hello,
in my greenhouse I'm using Lance Birk's receipe which is doing well and makes pretty pots.

6 to 8 parts (4 with Phrags) medium bark (previously washed)
1 part garden moss (very well prepared and washed to remove all debris and insects), cut in small pieces
1/2 part river sand

 

[Markedg]

Thanks everyone for your replies. Here in Ireland, it gets light from about 5 am to nearly midnight in the late spring/summer. It is not always sunny either as it tends to rain a lot. In the winter, the opposite happens, it doesn't get bright until 8 am and dark by 4:30 pm.
I decided to repot the multis that I got from Sam Tsui late last August. I found that quite a few had mushy roots but I could see roots starting to come out from the base. The leaves were turgid and looked healthy. I repotted into straight medium bark and hopefully with the good weather we are having, those roots will keep growing. The ones I got the year before had good roots and the root tips were growing.

I have learned a lesson that with the Irish climate, if I buy near blooming seedlings, I will do it no later than June to allow time for the roots to grow. I have other multis that I have had for a few years and I have no problems with them.

Does anyone who is successful with the brachys have any tips? I have 2 that grow and bloom with no problems. But a few others, I have been very careful as I have read they are prone to rotting and have brittle roots. I have a bellatulam that I rotted the main growth but the side shoot is growing. I have 2 hybrids that have finally have buds showing.

I have been checking this forum for quite awhile and you are a very knowledgeable group of people. Sorry about all the queries but I do like paphs/phrags and I want to make sure that I grow them the best I can. Again thanks for all your help.

 

[goldenrose]

Hello,
in my greenhouse I'm using Lance Birk's receipe which is doing well and makes pretty pots.

6 to 8 parts (4 with Phrags) medium bark (previously washed)
1 part garden moss (very well prepared and washed to remove all debris and insects), cut in small pieces
1/2 part river sand

I started giving it a try last spring, seems to be working for me.
The book I have lists 8 parts bark, 2 parts moss & 1 part sand.

I'm becoming more successful with brachys, or should I say less intimidated. Your 50/50 mix seems right on with them and good air movement is a must!

 

[Carper]

:rollhappy::rollhappy:Hi Markdg,

I also grow mainly the multifloral paphs and phrags with reasonable success. My greenhouse was completed about september last year and they have certainly come on immensly for the extra light, humidity, air circulation etc. I have gained a lot of help recently from this forum which I feel is helping me produce excellent growth in what I feel are fairly demanding plants. You mentioned MSU, and this is what I feed. It is Akerne's mix 13-3-15 which I feed presently twice per week or when I think the pot needs watering. I feed at about 750 M/s which is not doing any damage to the plants. I supplement calcium and magnesium in very small quantities at every feed and am now foliar spraying weakly most days. This is definitely producing healthier looking plants but the time will tell when the flowers are produced, fingers crossed! With regards to the medium, I have gone all husk with additional air holes in the pots and it is working a treat to date. I followed the Antec article on the web for the prep for this medium to ensure the max removal of any salts was made. I've been deliberating for the past 6 months on a medium, but this is simple and its working for me.
To end, I would recommend this forum to anyone, because these members have been there to voice their opinion and give advice. And for certain novices like me, its well appreciated!!!

Gary
UK