Fertilising Cypripediums

[Stephen Vella]

Theres been much debate on the topic and it seems that the hybrids can and do prefer inorganic fertilisers and arnt fussy about what you throw at them.

Im wanting to know what the growers here have to say in regards to fertlising their species and hybrids?

In pots and out in the garden..is it any differant?

Organic or inorganic, whats the NPK?

Was told to avoid urea..is that true?


cheers
Stephen

[Anthony Darby]

Inorganic every time. That's why you should use a compost that is 80% inorganic plus 20% bark and loam, which is nutrient poor. Inorganic can be controlled and washed through.

[Maren]

The first principle is to find out what your plant needs. You do that by studying where it comes from and what is known about its natural environment, acid or alkaline, wet or not etc..

Regarding organic or inorganic fertilisers, I don't think it matters. I use a variety such as tomato food, Maxicrop, Miracle Grow, seaweed extract and others. To know how much to use, I employ my most important gadget, a conductivity meter, which measures the content of dissolved salts to determine the strength of the fertiliser solution. My meter measures in units of microsiemens (µS) and I aim at 600 µS with practically every watering.

It also helps to understand that there is a difference whether you use rain water or tap water. If you use rain water, the initial conductivity (content of dissolved salts) is low, in my case about 15 µS and one you can add more food to reach the magical 600 µS.  Tap water, however, has a lot more salts to start with, in my case about 500µS, as I live in a very chalky water area, which gives less scope for adding fertiliser before the 600µS is reached. So there is no point filling up your watering can with 5 gallons of water and adding what it says on the fertiliser bottle, because you may under- or (more seriously) over-feed your orchids, which can lead to root burn.

Urea as a source of nitrogen should be avoided as the nitrogen derived from urea does not show up when measuring the strength of the solution and can lead to overfeeding.

I agree with Anthony that an inorganic substrate is more likely to allow cypripediums to survive the average British winter (cold and wet). It also avoids accumulation of salts which could seriously damage your plants. I go even further and avoid the organic content altogether, using a mixture of equal parts of Seramis and well washed pumice. This means that I don't need to re-pot for years, as there is nothing in the pot that can go off (bark) or change the alcalinity/acidity of the growing environment.

The bottom line: find out what your plant needs and give it what it wants.

[Jeff Hutchings]

I have used Tomorite for the past four years, feeding at 1/4 normal dilution every 2 weeks. My commercial mix is based on one used by Peter Corkhill. Equal portions of perlite, pumice and 2-4 m grit plus up to 15% Melcourt bark products. Peter prefers Cornish Grit but the only supplier I can find wants £300 a tonne I will continue with what I can find as long as it is inert. As my overhead watering system sprays the plants for a minute every hour during this hot weather I do not have a problem with a build up of unused fertilizer.

I found that Seramis did not work for me and I lost numerous plants in the summer when I used it as the alternative to pumice.

Rather than have to give individual instructions to each customer as to preparing their soil I now recommend growing plants in 5 to 10 lt pots using the mixture I described and plunging the pot into the garden in a suitable position. I have seen excellent plants that were planted some years ago in this way and they are thriving. All the owner does it feed the plants well and covers the dormant plant with additional grit each autumn.

[Stephen Vella]

Anthony you make it sound simple...thanks for the advice.

Maren a conductivity meter is something I will have to get, takes the quess work out of it. I use Dam water and tank water. Im wondering if Cyps would prefer all that chalky water?? and I will stick to the inorganics.

Jeff interesting to hear that seramis did not work for you...I use seramis/ perlite/(coco fibre/bark 10%)and it seems to keep the mix moist/free drained. Do you know why it killed some of your plants?

[angie]

I spoke to someone at the international conference at Nottingham ( forgot their name ) and they talked about pumice, is this product as hard to get as seramis.

Angie

[Peter Maguire]

That would be me Angie,

I obtained my pumice from a firm in North Yorkshire called Viresco. I stocked up last year as they announced that they wouldn't be stocking it in future and were selling off their remaining stocks. I've since heard a rumour (unconfirmed as yet!) that they were so impressed by the number of people who wanted pumice that they may begin stocking it again.
Otherwise it's a bit hard to come by in the UK. There was an extensive thread on the 'composts' section of the forum last year (here's the link: http://www.srgc.org.uk/smf/index.php?topic=1569.0) which may have listed other sources.

[angie]

Hi Peter
Just shows how bad my brain is I didn't think it was a forum member but yes it was you, its all coming back now  . Thanks for the link.  I thought it was great conference, my first but certainly not my last. I was exhausted by the time l got home, so much to take in and all that food didn't help. l was ready for a sleep after every lunch.
Will try that company, hope l manage to get some. Thanks.

Angie

[Graham Catlow]

Hi Angie,
If you find someone that sells it please informs us here. I too would like to get some.

[angie]

Will do. Have emailed some companies. See what happens.

Angie

[angie]

Can anyone give me the size of pumice that I would require. The company called me back today ( Viresco ) and said they had different sizes so before I place a order I thought it would be helpful to find out what I need. Thanks

Angie

[Maren]

Hi Angie,

I'd go for 4mm max, that'll come as between 2mm and 4mm.

[Peter Maguire]

Angie,

That's good news that Viresco are selling pumice again - I think that, of the range of grades that they have, I used 3-5mm size - roughly the size of dried peas or chickpeas. The smaller size is good for seedlings (if you're feeling bold and fancy a challenge). I also obtained a bag from them of a larger size (5-8mm?) which is too big really. I tried breaking it up with a hammer; doesn't work, you end up with lots of dust! 

You can 'recycle' the pumice: I'm currently using about 75% pumice to 25% leafmould. At repotting time I find that the leafmould has packed down and is too dense, especially if earthworms have got into the pot. I therefore repot in fresh mixture and the old mixture is put in a black plastic pot or spread on a tray and left in the greenhouse for a week or so to dry. It can then be sieved to get rid most of the organic component (this is where the 3-5mm size is useful - it stays in the sieve). The 'old' pumice can then be combined with fresh leafmould and re-used. If you have a large collection of Cyps and plants requiring a similar regime  , then you don't need two year's worth of pumice, as after a week or so, you are using pumice that his dried from your first repots of the season.

My (unsubstantiated) theory is that any mycorrhizal fungi associated with the plants can be passed on through the pumice as it is re-used, giving them a head start in the new mixture.

Oh yes, with a mixture this free draining, you need to water regularly, mine are watered automatically with a sprinkler for 15minutes twice a day, which works for me with plastic pots standing on a sand plunge. They are also fertilised regularly with weak tomato fertiliser, the regular watering flushes any excess away, as Jeff Hutchins said in his post.

[angie]

Peter thanks for all this information. He never said what they had but said they had a few grades of pumice. I will speak to him tomorrow and hopefully will be able to get some.
I only had a couple of Cypripediums but I got some from Anthony D last year, lovely healthy plants, now I think I am hooked.
I had some a couple of years ago before I came to the forum but I kept them to dry through the winter and lost them. I thought they were a bit tender. Should have read up on them before I bought them, expensive mistake  I am never sure how much water to give my plants in winter but speaking to Anthony and seeing where he kept his plants was a big help.
Isn't this forum great, where else would you get help and advice like this and its free 

Maren thanks 

Angie

[angie]

Peter spoke to a really nice gentleman today from Viresco and he is sending me some samples and I was glad to hear that he had 2-3mm in stock and will send to Aberdeen. Thanks for the help.

Angie