My Flasks

The various sizes of containers that I use the most.

My Flasks.

For almost all orchid species I use four to five sizes of containers to sow, replate several times, and eventually on to final replate. Sowing of orchid seed is done onto a previously prepared, sterile medium in a squat, recyclable container with a tamper evident seal, I do not generally use a vent at this stage, the seed and first size protocorm will have sufficient sterile air in the headspace above the medium for germination and early development. The orchid seed does not require much light to germinate, terrestrial orchids do not require any, so, since these squat containers will stack, less space is taken up by them.

First replate.

first replated orchid flask
Selection of first replates.

Several weeks to months later, the germinated seed is ready for the first replate, this provides the developing protocorm with more space and fresh medium, I often use a similar style, squat container for the first replate but with a vent fitted to the lid. Vents provide a gas exchange for the protocorm or seedling, the ones I use have a pore size of 2µ, too small to permit spores of potential contaminants to pass through but large enough to permit gasses to permeate, providing filtered air whilst maintaining sterility. Every few months, as the protocorm develops, further replates are made into a taller version of the same type of container also fitted with a 2µ vent, this will accommodate them until the first leaf and first roots have grown.

Protocorm of Dendrobium speciosum grandiflora ‘Giant yellow’ at first replate.

Moving on.

honey jar orchid flask
Phalaenopsis pulcherrima v regneriana in a wide diameter jar.

For most species, eventually, a taller container will have to be used and I switch to a glass jar, generally a ‘honey’ jar. I use these because I am able to source recyclable plastic lids for them which can be autoclaved. I could use a jar with a metal lid but I find that metal lids rust when drilled for a vent, so I avoid those. Each time a replate is made, the seedlings are sorted by size.

Final Orchid Flask

Once the seedlings are big enough, I make one last replate, always sorting by size, switching the media from a maintenance type to a type that encourages greater root formation. Depending on the plant form, these ‘final’ replate jars will have a varying number of seedlings placed into them. Seedlings similar to the Phalaenopsis form, which have wide-reaching leaves, will be placed in a jar with a greater diameter than seedlings similar to Oncidium or Cattleya, which tend to grow upwards rather than out to the side. Generally, I will place from three to ten seedlings in these ‘finals’. Of course, this means that I have to use more jars which will take up more space on the racks but this approach allows me to remove them from the jars at what I consider to be the optimum time, as well as providing the seedlings with the space they need, and I avoid having to deal with large numbers of widely differing sizes of seedling from the same jar.

With such a diverse family as Orchids, there are always exceptions such as seedlings of Stanhopea, Eulophia, Catasetum, or any other similar types, whose seedlings grow very fast, very tall, and which will not tolerate depleted media or poor gas exchange, for these I replate more frequently with final replate into much larger jars. The resulting seedlings are big with well-developed pseudobulbs, in turn, this makes them easier to acclimatize to life outside the jars.

In most cases, up to two years or more will pass from the sowing of the seed before the seedlings are ready to be removed from the jars. For all of that time, they have grown in ideal, sterile conditions so the first few weeks outside of the flask are vitally important, any roots present at de-flask do not function as expected because they have developed in a gel medium, thus making seedlings vulnerable to desiccation or rot. They will require careful treatment to get them past this first hurdle.

Typical Orchid genera that I may have in flask at any one time might be the following but the list is ever-changing as seedlings are de-flasked and new ones are added due to new seed acquisitions and subsequent germinations.

Aerangis species
Aerides species
Angraecum species
Cattleya species
Bulbophyllum species
Dendrobium species
Laelia species
Neofinetia species
Odontoglossum species
Oncidium species
Ceratocyilis species
Eulophia species
Euchile species
Phalaenopsis species
Zygostates species