Terrestrial orchids 2015

[Steve Garvie]

Steve what soil mixture to grow yours in?  As I have a couple of seedlings that need to be deflasked.

I used a mix of 30% quartzite silica sand (size-20; 16/30) + 20% cat litter (Tesco lightweight, low dust) + 20% perlite + 10% pumice (4-6mm) + 20% loam.

There are probably easier mixes that are just as effective. The above is an open free-draining mix that holds some water but has good air-filled porosity. I started using silica sand on the advice of Jan Moors of Crusticare/Albiflora. The sand is inert and free-draining but its physical properties seem to encourage fluid movement through capillary action.

The loam was collected from some molehills in a small Beech wood. The underlying soil is sandy and this loam is very crumb-like with some organics derived from the rotted Beech leaves. The loam is treated (in small bags) in the microwave when my wife is at work (the latter is very important!).

[Neil]

Steve

Thanks for that, is not too dissimilar to what I use from for my Winter Greens.

[Maren]

Hi Steve,

does your wife read these pages?

Just one question about the quartzite silica sand (size-20; 16/30): how does this translate into millimetres? can you turn your fraction into decimals please, just for me???

[Neil]

Maren  its 0.5mm on specification

It is primarily used for water filtration.

[Steve Garvie]

Hi Steve,

does your wife read these pages?

Just one question about the quartzite silica sand (size-20; 16/30): how does this translate into millimetres? can you turn your fraction into decimals please, just for me???

Maren, it is lucky for me that my wife hasn't discovered the delights of the SRGC forum.   Yet! 

As Neil has said the quartzite sand is 0.5mm diameter, though other sizes are available. The sand is clean, inert and is used as a filtration medium for swimming pools and aquaculture. I quoted the "size-20; 16/30" as these are the descriptors used when this product is advertised on websites/eBay/Amazon. I can assure you I am a thoroughly modern metric man! 

[mark smyth]

Ophrys spruneri  with a split or double lip

[mark smyth]

I used a mix of 30% quartzite silica sand (size-20; 16/30) + 20% cat litter (Tesco lightweight, low dust) + 20% perlite + 10% pumice (4-6mm) + 20% loam.

No moles here and never seen silica sand for sale. Is there a substitute?

I think it was Tony who said he grows his in 9cm clay pots. I could only get a few last year so all went in to the next size up which was 11cm. Homebase now has stock of the 9cm pots

Spotted an invasion of aphids today so all plants in the greenhouse were sprayed this evening

[Yann]

Nice Ophrys Mark.

[Neil]

Mark try an aquarium shop or Pet store.  It is also sold as silver sand.

[mark smyth]

OK thanks

Yann I bought it last year so I guess it will not be the same next year

[mark smyth]

I've probably asked this 10s of times. What size pots do you guys favour?

Over the winter I've been watering the sand plunge and not the pots. On warm days can I water down the edge of the pots?

[Steve Garvie]

When in leaf up to the point when the first few flowers are opening I water freely. Due to lack of time I often use a hose. Whilst the leaves get wet I have fans which operate on timers so the foliage dries off even after a soaking. If the mix is free-draining and poor in organics it is difficult to overwater.

Two years ago I bought some young Orchis. I had planned to pot them as a group in large pots. When I first got them I didn't have the time to make up a proper mix and group pot them. I stuck each in a small long tom pot containing only sharp sand (concreting sand). They were plunged and I intended to pot them properly the following week. I forgot about them until they erupted from the sand -it was then too late to repot them. I kept them moist, applied dilute fertiliser a few times and kept the plunge moist. Without exception they all grew very well.
Underpotting in sharp sand seems to work very well as long as the plants are not allowed to dry off whilst in growth. Small pots with free-draining medium seems to be the way to go. In the past I lost a lot of Med orchids to rot but never lost any to dessication. Now my mixes are lean, free-draining and have little organic content. I'm growing Med orchids better now than I ever have before -I'm sure this is down to lean fast-draining compost and better ventilation.

[Maren]

Hi Steve,

thanks for the millimetres, that helps.
I have a couple of bags of quartz that have been languishing for years. Bought them from Jan Moors when I last visited him in Belgium and haven't found a use for them. The grains are much larger than your specification, one is 2mm and the other is 1mm on average. Do you think I can use that all the same as part of in cypripedium compost or would it make it too heavy?

[Giles]

Maren
The articles are available *free* as individual pdf's:
http://onlinelibrary.wiley.com/doi/10.1111/curt.2015.32.issue-1/issuetoc

[Maren]

Thank you, I managed to download it. Good article.