Pleiones - why repot every year?

[Mark Griffiths]

It seems the standard advice is to repot these every year. I was wondering why. I use orchid mix and that contains no nutrients - it basically gives the plants something to anchor to. It's important for the compost to be open to allow air to the roots. I grow a few tropical orchids where basically the advice seems to be to keep them in the compost until the compost starts to break down structurally - but that takes years.

I took a year off from repotting and it seems the pleiones were better the following year. Anyone just left them in the same compost for 2-3 years?

[SteveC2]

A few reasons why I repot annually;
My pleiones spend the summer outside and inevitably the weed seeds get in, as do the pests.  Repotting allows you to completely remove these.
Although I am frequently told that pleiones are shallow rooted and only need small containers, I find that many of my pots are pretty well packed with roots come November, roots which are now dead and will soon decay.  As the roots are dead there is no chance of damaging them, unlike with the tropicals where the roots persist for years.
I have no evidence for this one, but I don't like the idea of leaving the old bulbs in situ to decay and whilst some can be removed I don't think you'd be able to get them all out without repotting.
I try to pack my bulbs quite tightly, but leaving them in situ for two or three years would leave the pots very, very, full, especially with some of the vigourous, big bulbed varieties like aurita.
Some I grow in virtually all moss which really does need changing after a year.

The autumn flowering varieties are a different matter.  I'm still not convinced that they ever really go dormant, especially saxicola, and I try to leave these well alone if possible, or at least am very very gentle with them if I must repot.

[Guus]

Hi Mark,
I usually do this. I keep them in the same compost for many years and do not take them out. I keep my Pleiones in the special 'pond-baskets' (perforated plastic baskets that are used to put waterplants in, in your pond). Over the years there is growing lots of mosses in the baskets and the plants seem to like that, the moss covers part of the bulbs. I do hang the baskets in the trees in my garden and keep them quite wet (all the water runs out).
This year I took humilis out for the first time, hope they will do wel next year...!

Greetings, Guus

[Maren]

Hi,
I'm with Steve2 on this one, especially to avoid proliferation of pests and diseases. If I don't take the bulbs out of the compost, I don't know what they look like underneath i.e. what damage there may be 'underground'. As I have developed the habit of throwing away anything that is damaged in any way, I seem to have reduced the incidence of problems.

Regarding autumn/winter-flowering pleiones, I too am very careful as they never quite seem to go dormant. However, I have found that they are easily plucked out of the very open mix I use and can be re-potted without damaging them, even cutting the old and not quite dead roots. According to Ian Butterfield, these roots do not die back to the bulb when cut, unlike the spring flowering pleiones, and new roots soon emerge. If I am at all worried, I just move the plant(s) to a bigger pot/bowl and pack fresh compost around the existing rootball.

But I appreciate there are many ways of growing pleiones successfully.

[Mark Griffiths]

thanks for the replies. I sort of thought the repotting thing was regarded as being essential from the perspective of the state of the compost - but it seems so far from the replies it's more a hygiene thing.

One thing I find odd is that despite following the usual cultivation notes after growing them for probably about 30 years on and off I usually find the majority simply mark time. I get bulbils but they never mature and probably something like 50-60% of the plants just give me the same flower year after year for decades, the remainder either increase a little or just die out completely. Why I don't know. When, due to other things in my life I left them I seemed to get a slight improvement, or at least no real losses. And because they don't seem to increase much over crowding is not going to be an issue anytime soon. 

I think the thing that frustrates me most is the decade long "hanging on" - if I'm a complete dunce at growing these things I'd prefer they do the decent thing and just die rather than constantly fooling me into thinking one day I'll get it right.

[Tim Harberd]

Hi Mark,
   A few years ago, I split my collection into two parallel groups, and every year I re-pot the one that wasn’t re-potted last year. There are a few reasons (excuses?) For this.
1) I couldn’t face doing the whole lot every year. It would probably be a 5 day job.
2) I do like showing, and recently re-potted bulbs, with decent flowers, have a tendency to keel over in transit.
3) I’m always adjusting the re-potting mix, and I wouldn’t want to risk the whole lot on my next best guess. Also, although some ingredient may have the same name as last year, I’m not convinced that it is necessarily identically the same. (For example, I strongly suspect that the fungal flora of composted bark is variable)

On the related subject of increase, I reckon some of my cultivars can double over two years. (Tho’ winters like 2010/2011, where I lost up to 90% of the stock, can make a nonsense of such a claim.) I had one yunnanensis which ‘hung on’ as you describe for years, and never flowered. Others, like confusa, seem to ebb & flo.

My sister grew a pot I’d given her for years in the same compost. If I thought I could get away with it, I’d split the collection into three groups. I live in fear of brevipalpus! And the re-potting procedure always includes a soaking in Neem.

Tim DH

[erf]

Hello
I also repot every year. One of my reasons is, that for the spring flowering species, when I take them out of the compost, I put them in papier bags and put them in the fridge for 2-3 months. Keeping them outside in Denmark I will not risk, since the temperature from time to time drop to minus 10-15 C for longer periods. When I take them out of the compost and put them in papierbags, there can be many more in the fridge. I don't thing that buying another fridge will be appreciated of the wife.   .
At the same time its a good opportunity to dip them in neem oil.

[Maren]

Hello Mark,

it is true, some pleiones are more prolific than others, sometimes they go backwards and one wonders why.. But all benefit from regular watering and feeding. I fell off a horse in late March and broke a few ribs. The weather was hot but I was unable to water as often and thoroughly as I should have done. They didn't like it.

[Graham Catlow]

All my Pleiones were overwintered in the fridge last year and repotted in the Spring. Something I had done for a few years. This year, however, they will remain in their current pots and compost and I will see what happens. I had several abort their flowers last year and thought the shock of leaving the fridge into somewhat higher temperatures may have been the problem.
I had P. limprichtii in the same pot and compost for three years and the quality of the bulbs and blooms increased during the period.
I use a very open but organic compost that I prepare myself from pine duff, pine needles, beech leaf mold, general purpose compost, composted bark and wood moss.
The results of this method will only be apparent in 2014 and perhaps 2015 if things look to be going well.
As Maren says ' there are many ways of growing Pleiones successfully'.

[Mark Griffiths]

thanks for the further replies.

Tim, I remember when you first started showing the Shantung hybrids and reading your work on x confusa. I guess now neem oil is the only thing amateaurs can get hold to use against the dreaded mite?

Erf, that's interesting - I leave mine in compost over the winter - the greenhouse is heated to 5C (often drops lower though). I'd have similar complaints from my wife. She was not impressed when I told her I'd used the microwave to sterilize leafmould in the past.

Maren - yes the going back and forth is maddening. Capt. Hook always did well for me - last year it did very badly. I had a x confusa that stopped flowering for 10 yrs - then flowered and then finally died. You saying about not watering so much in March made me think - I dodn't think I am watering very much at that time of year because advice was to not to water much as they start off - I know you grow alot - how often do you water as they start to grow?

[monocotman]

I've been following the discussions with interest and would like to offer a few comments.
I repot every year principally because it is the only way I can keep the bulbs frost free.
They all go into an unused fridge in bags in the garage.
This protects them from the worst of the cold.
It would not be possible if they were still in their pots.
I suspect that they would be fine for two years in the same pots if they weren't too overcrowded.
I've found that I get good rate of increase from nearly all hybrids, especially the rakata and shantung clones.
The species are much more hit and miss.
I reuse the compost as much as I can and refresh it with more reconstituted NZ spag and bark.
Plant growth improved alot when I added spag to the bark and perlite mix,
Regards,
David

[Maren]

Hi Mark,
sorry I confused you over watering pleiones at the beginning of making new roots.
I should have been more precise:
- broke my ribs at end March,
- didn't water much during April.

That's when most of my pleiones were well under way, having been potted in January.

I conclude from this experience, that developing pleione roots may be more susceptible to dry conditions than established roots. Will do better this year.

[Mark Griffiths]

thank, how much do you water before the leaves are fully formed? once a week or forthnight?

[monocotman]

On the subject of watering - I don't think that the advice of no water at all should be taken too literally.
I do give some water occasionally when they're just starting off.
They get one early on to settle the compost, otherwise they're very prone to fall over as the flower and roots develop.
I use a houseplant spray bottle then to give the pots a bit of water about once a week when in flower when I see the bulbs starting to shrivel.
I remember visiting Jacques Amand's nursery several years ago and seeing a batch of x barbarae or grandiflora in full flower outside in a shade house and they were completely wet through. They were growing in a very peaty compost.
When I asked about this the comment was that they would be fine as long as they were kept cold.
It was the combination of wet roots and high temperature that was the problem.
I can't say I've ever confirmed.
David

[Maren]

Hi Mark,

when it comes to watering, I don't work by calendar but try to maintain a condition of slight moisture in the compost. Depending on temperatures i.e. rate of evaporation, and absorption by developing plant roots, that could mean giving a little water every day, or week or two weeks. If the weather is cooler and the plants not very advanced, I give less water. But I do not keep the compost bone dry.

Any advice about not watering when pleiones have just been planted assumes that the compost was moist, not wet or dry, when the bulbs were first potted. - Hope that helps.