planting depth

[mark smyth]

This weekend I plan to repot my Orchis and Ophrys.

I lost a few over the winter due to neck rot and others didn't make a replacement tuber. How deep do you normally plant yours? I usually have mine about 3cm deep. Is this too shallow?

When I knocked out my pyramidalis I thought they hadn't made new tubers but was amazed to find the new ones almost at the bottom of the pot.

[Neil]

That is what I plant mine at, with regards to neck rot you mixture needs more opening up with grit. 

[mark smyth]

Thanks Neil. My mix last year was about 50/50 bought top soil and grit. Should I add more grit or maybe perlite? What about some leaf mould for food?

[Steve Garvie]

I use a mix of VERY coarse gritty sand with perlite, Tesco low-dust lightweight cat litter and only about 10% loam. I no longer add additional organic material. This mix looks far too lean and is super fast draining but has a very high air-filled porosity. The perlite and baked clay granules adsorb moisture and release it back into the sand maintaining a stable humidity whilst the orchids are in growth (I water around the edges of the pots freely and find it difficult to over-water using this mix). I use quarter strength liquid feeds containing no ammonia/urea nitrogen every 2nd/3rd watering. The plants are all in clay plunged pots and are kept frost-free with air circulation provided by a fan on a timer. With this regime I don't get collar rot and many species have produced more than one tuber. The critical time when watering is in the flowering phase, some ophrys need gentle drying off from about the time the first few flowers have opened. At this stage the new tuber has already fully formed and if the compost is too wet the old withering tuber can rot; usually the new tuber is adpressed against the old one and so the rot spreads to the new tuber. In other species of ophrys watering can continue until the last flower opens.

Whilst a few orchis behave like ophrys most are still bulking up their new tubers whilst the flowers are opening so need to be kept damp for a bit longer.

In autumn it is falling temperatures (especially at night) which seem to encourage new growth. The new roots are initially in a rapid growth phase and lack root hairs so too much moisture at this stage -as in heavy claggy loam results in root rot. A very open air-filled light fluffy mix encourages the new roots to roam wide and far before the root hairs develop and the plant grows better as a result.

Some years back when on a birding holiday in Mallorca I came across a small colony of ophrys growing through the cracked surface of an old metalled road -they were growing in almost pure grit and stone debris with no hint of loam or organics. Up until then I had always assumed that all orchids need some organic material to grow -something to feed the mycorrhizal fungi; however since avoiding organics and using only very open porous mixes I now find I am managing to grow a whole range of hardy orchids including Cyps, Ophrys, Himantoglossum, Amitostigma and Calypso whereas before they just rotted. I now think of orchids and their mycorrhiza as being a bit like lichens which as you know are composite organisms comprised of symbiotic fungus and a photosynthesing moss/algae. Lichens can grow on very lean mixes and even bare rock from which they contribute to soil formation by slow "corrosion" of the rock by enzymatic action.

Keep your orchids away from organics and heavy soil and I think you will get better results.

(Forgive me! Having just re- read what I've written above it sounds like I think I am some sort of orchid guru -I am far from it but my switch from previous heavier loam based mixes containing organics to porous lightweight inorganic mixes has totally revolutionised my ability to grow orchids.)

[mark smyth]

Thanks Steve. Well written

[mark smyth]

Repotting almost finished. Just need to add a dressing of grit. The mix I made was 4 parts gritty sand, 4 parts perlite, 4 parts clay cat litter from Pets at Home and 1 part recycled pot contents which was a mix of top soil, grit and sand. How does it look?

Lots of tubers have noses showing with some showing the start of roots. Big variety in size of replacement tubers from large down to pea sized or smaller that may not flower

Found another tuber that had produced two layers of roots

[Steve Garvie]

Mark I may be wrong but it looks like you may have used Fullers Earth clay cat litter -if so then this clumps when wet and will cause no end of problems. You need to use cat litter made from BAKED Danish Moler clay granules -a product that looks and behaves like Seramis. There may be other brands of cat litter like this but the only one I know of is the Tesco low dust lightweight cat litter. Try wetting a sample -the drainage should be impeccable with no clumping whatsoever. Apologies if you have in fact used the right type -but if not ->chuck it and make up a fresh mix with the right stuff.

[mark smyth]

I'll check it out tomorrow but these 'rocks' are hard

Mark I may be wrong but it looks like you may have used Fullers Earth clay cat litter -if so then this clumps when wet and will cause no end of problems. You need to use cat litter made from BAKED Danish Moler clay granules -a product that looks and behaves like Seramis.

[mark smyth]

Its called Sophisticat and stays whole

[Maggi Young]

Its called Sophisticat and stays whole

Just looked up this brand and it says it's manufactured from 100 per cent recycled softwood  -this is not what's wanted in this instance though , is it? Or am I getting the wrong end of the stick?

[Maren]

Well spotted, Maggi, the cat litter that may be used for orchid compost should have been made of baked clay. I use cat litter quite a lot instead of Seramis which is expensive and sometimes difficult to get. The brands I use are:

http://www.pet-supermarket.co.uk/Products/CN194003/sanicat-pink-litter
and
http://www.tesco.com/groceries/product/details/?id=265235247

[Matt T]

The Sophisticat non-clumping litter that Mark bought from Pets at Home is made of Danish molar clay, so he has the correct stuff: http://www.petsathome.com/shop/en/pets/lightweight-non-clumping-pink-cat-litter

[Maggi Young]

That's good  to hear - I had found this : http://www.wilko.com/cat-litter+trays/sophisticat-beauticat-non-clumping-cat-litter-30l/invt/0314611 which is made from recycled wood.

[Tony Willis]

this is the stuff from Pets at Home.

I use it for fritillaria seedlings,orchids and now I am growing Clematis acerifolia in it.

When the plants die you can wash it and re-use!

[Neil]

When the plants die you can wash it and re-use!

Do you kill a lot then!