Calanthe 2015

[reifuan]

As per usual, this Taiwanese Calanthe sieboldii is first to flower. My plant has increased from one to three flower spikes. Unfortunately, two of them are malformed, probably due to frost damage at an early stage of development

[Maren]

Hi Reifuan,

I notice that you haven't had any replies yet. That surprises me a little because Calanthes are getting very popular. At our spring show (Thames Valley Orchid Society end of March), a trader offered these in bud. They were all unnamed hybrids and there were so many shoots in the pot that it looked like a bunch of asparagus. I expect that these come from the house of Anthura, I recognised the pots.

There is just one problem with Calanthe sieboldii and many others:  they are not reliably frost hardy. Of course, there are many varieties growing in different places, so conditions will be different for each. Sadly they don't come with individual care labels to tell you what the minimum temperature may be.

I have lost quite a few in earlier years and have since experimented, using different 'climates'. Some grow with my spring flowering pleiones, where it can get down to 0°C on occasion for a very short time. The pleiones don't seem to mind that but the calanthes don't like it much. Others grow with my autumn flowering pleiones (e.g P. praecox), which are kept at a minimum of 5°C. They grow wonderful leaves and multiply rapidly but don't flower much. I shall try something in between next because I really love these.

Ian Butterfield manages to grow calanthes exceptionally well in his pleione greenhouse under the staging. They are huge, with clean leaves and covered in flower spikes. You may think it's too dark under the staging, but his plants get quite a lot of light, because the staging is made of wire mesh and not very crowded. Good luck with yours.

[SteveC2]

I have several in bud, but they seem to be determined to keep me waiting.
It will be interesting to see how the Anthura "asparagus" does in the hands of mere mortals without the Dutch magic.  I bought three last year.  The one that looks like sieboldii has doubled in size  to four shoots and has huge buds about to open.  Both the Kozu hybrids have more than doubled in size, up to eight shoots, but one has four flower spikes, the other none.  All were treated the same and sat next to each other, so mixed results for me.
My good old species tricarinata and brevicornu look tiny by comparison, but have a certain charm compared with the cabbages, sorry asparagus!

[reifuan]

all my plants are in bud too, except C. henryi, which had a rot problem and lost the three shoots that were going to produce flower spikes.
I agree that they can be a bit fickle, my C. discolor went from 1 to 2 shoots last year but produced no flowers, this year out of four shoots, one has buds. My C. hancockii had two shoots and one flowerspike in 2012 and 2013,  4 shoots and no flowerspikes in 2014, and had 8 fat shoots that were all set to produce flowers this spring. That is, until a rat with a taste for 'asparagus' came along and chewed off all but 2. My C. brevicornu suffered even worse, out of twelve shoots only a small one is left.
The hybrid from Anthura i bought last spring has increased well and has two big flowerspikes just emerging, probably a third one on the way. I'm glad to see it doesn't need the warmth of a greenhouse to perform well.

[Tony Willis]

Mine have barely started into growth yet apart from Calanthe tricarinata and they are all in flower.

I have had both C.sieboldii and C.reflexa for years and never had a flower on either. I keep them just frost free

[SteveC2]

Tony, my experience with Calanthe reflexa is that the thing most likely to stop it flowering is summer heat.  My two flower reliably every August unless we have a hot summer when the buds abort.  Keep them as cool as possible, shady and damp and pray!

[Tony Willis]

Steve

thanks for that advice,I will try some shade but I am having difficulty remembering when we had summer heat. I have been keeping them in quite bright light.

[SteveC2]

None of my Calanthe ever see the sun, at least not until late afternoon and then only for a little while.  They are outside on the north side of my greenhouse all summer and when they sun does come far enough round there are trees to give some shade.

 About four years ago, maybe longer, I lost my  reflexa flowers to a mini heatwave, since then they have been fine.

[Peter Maguire]

The above comments on Kozu and other hybrids are interesting, as I too have found there to be phenomenal growth on the plants I obtained last year. Whether they flower as well for me remains to be seen....
I do wonder whether the compost used seems to have some relevance to this - previously I have used a reasonably highly organic mix watered regularly and also fed frequently as Jeff Hutchins recommends on his website. But the plants have never thrived, and have certainly never flowed after the first year.
One of several hybrids I obtained last year came from John Amand at Gardening Scotland. It seemed to be in its original pot and when repotting it this week I had to cut the pot off the rootball as the significant mass of roots had distorted the pot: the potting medium inside seemed to be totally bark chips. A couple of plants that I obtained from Jeff earlier in the year seemed to have been repotted into larger pots. The original potting medium again seemed to be bark chips, with a large number of roots growing around the bark mass where the edge of the original pot would have been. However there were also a lot of roots growing into the surrounding compost, which seemed to be a 50:50 mix of perlite and organic matter. Teasing out the  rootball to remove all the old compost left no discernible difference between the old and new roots.
I eventually elected to repot the plants using a mixture of the Cypripedium mix that I use (mostly pumice, to give excellent drainage with some moisture retention) and a significant amount of organic material. The eventual mix was about: pumice 30%, perlite 20%, composted bark 20% and coarse bark chips 30%, but I am now beginning to wonder whether this may be too moisture-retentive and could cause rotting of the roots, so should I increase the amount of the bark chips to open up the compost?
Any comments/advice would extremely welcome!

[Maren]

Hi Peter,
I just came across Ian Butterfield recipe for calanthes, which he grows extremely well. Of course, it is not just the compost that ensures success, but here goes:

Ian's compost for Calanthe
Peat…………………...   6 buckets
Fine bark…………......   6 buckets
Perlite………..…….....   1 bucket
Vitax Q4………..….....   8cm pot full
Fish, Blood & Bone....   7cm pot full   
Dolomite Lime…….....   7 cm pot full

This would have to be scaled down a bit for the ordinary grower. Hope it helps.

[Peter Maguire]

Thanks for that info Maren, I may incorporate rather more feed into the compost mix.

It's the particle size that intrigues me, I would guess that in Ian's mixture the largest particles would be the perlite, perhaps 4-5mm diameter? The plants that I repotted from what seemed to be almost pure bark were growing in a mix with a particle size of 8-10mm diameter, probably about 30-40% air!

[Maren]

Hi Peter,
regarding size, it's a toss up between the fine bark particles and the super coarse perlite. Remember both get smaller during the growing year and when being re-potted in early spring, it's all a pretty airless lump of mush.

[SteveC2]

Not that I would ever argue with Mr. Butterfield, but a friend of mine who grows excellent Calanthe swears that, like Cypripediums, they dislike being repotted and this should be avoided until absolutely necessary.  Very confusing!

[Peter Maguire]

Maren, I'm not sure that these bark chips in the Calanthe pots were going to get smaller anytime soon - they were solid pieces of what looked like pine bark about the size of sugar cubes. I've repotted Cymbidiums after several years in similar bark composts and they haven't degraded much.

As it happens I had a quick chat with Jeff Hutchins at the Harrogate Flower Show today and asked him about the coarse bark. Apparently the hybrid Calanthes are raised in Holland where they are grown under cover and watered on a regular basis by overhead sprinklers so they are kept moist. As the outside area where I keep my larger terrestrials - Cypripedium, Calanthe, etc - during the summer is lightly sprinkled twice a day I'm tempted to use something similar as a basis for the Calanthe compost. The Cyps are already in 90% pumice and I'm thinking of trying 40% coarse bark chips, 40% 8mm pumice, with the remainder being made up of smaller organics to privilege the organic type mix that they seem to prefer. One can only try! 

Incidentally Jeff had some lovely, delicately coloured hybrids on the stand today - my collections has increase by two. 

[reifuan]

I grow mine in a range of different compost mixes (bark, cocopeat, cocnut husk chips, composted wood chips, supermarket potting mix) with varying moisture retention and drainage. It doesn't seem to make any discernable difference in terms of growth. Some require frequent watering to be kept evenly moist, others are only watered when there are long periods without rain. Another point is that finer organic ingredients like peat decompose quite rapidly, because of the large amount of organic fertilizer I give my plants.

As for repotting; I've never experienced any setbacks afterwards, they seem quite resilient to me. From what I understand from Japanese growers, they can be repotted at any time of the year except summer and early autumn, when they're forming new shoots for the following spring.