Treatment of Orchid Seeds for Shipping
How orchid seeds are collected, handled, and stored is very important to the eventual outcome with regards to success in long-term storage, flasking, and germination. If seeds are not collected and stored properly,
the chances that they will be unsuitable for flasking will increase. A few principles and a (hopefully) complete explanation as to the best techniques for dealing with orchid seed is found here.
Orchid seeds are “orthodox” seeds. This means that orchid seeds will last longer when drier and cooler. Some types of seeds- not orchids- require high levels of moisture, or they die. Similarly,
other types of seeds need to be kept cool- but not cold- to last as long as possible. Orchid seeds should be quite dry when stored (explained below), and kept cool. Even tropical orchid seeds are not harmed by low
temperatures; typical storage at 4 degrees C (refrigerator temperatures) is fine. However, freezing at -20 degrees C, -80 degrees C, or even in liquid nitrogen at -196 degrees C, does not seem to harm them- and, in
fact, may even allow them to be stored longer.
Orchid seeds need to be harvested at the correct time.
This aspect is probably the most difficult when trying to determine when capsules will ripen. Obviously, the easiest way is to allow the capsule to split. Unfortunately, seeds are generally lost when this happens; the capsule ruptures in the greenhouse- often with a crack so small it cannot even be seen- and the seeds “leak” out, lost to the winds in the greenhouse. There are several solutions to this potential problem:
* Remove the plant as the capsule approaches maturity, placing it in still air inside the house, or perhaps the potting shed.
* Remove the flowering spike as the capsule matures, and place it in still air, like the plant above, with the cut end of the spike in a glass of water like a cut flower.
* Remove the capsule, and slice it wide open on a piece of clean paper using a sharp knife- preferably a sterile blade, or a clean “X-Acto”-type knife. Flay the capsule open along the three lines
(“sutures”) where the capsule would normally open, and allow it to air dry. This works best with capsules that are very ripe, and look ready to open. Similarly, if you observe a tiny crack in the
capsule, it is desirable to use this technique as it is probably ripe, and should be removed to still air, opened, and allowed to dry.
* Remove the capsule that has cracked or has been flayed open, and place it in a large coffee filter that is then stuffed into a large jar with desiccant in the bottom. The silica gel capsules found in medicine
bottles are usually too large, and have usually absorbed all the moisture they ever will. However, special bead desiccant is available (please ask), and other desiccants such as calcium chloride,
“DrieRite, and similar may be used. Place desiccant in the bottom of the jar, insert the coffee filter with the seeds above it making sure they do not touch. Seal the jar tightly and place it in the
* If in a humid climate, capsules should be dried in a desiccating chamber, rather than in open air. Dry climates- such as the one where the seedbank is located- are best for collecting and storing seeds.
Sometimes we forget to stress to customers how careful they must be with their seeds to keep them from rotting.
Orchid seeds will mildew and become useless if kept moist.
It is very important to harvest and dry orchid seeds such that very little free moisture is left. The above techniques work very well to remove much of the moisture present, producing refrigeration-ready seeds. If any doubt remains as to how much moisture is left in the seeds, then they should be placed in a desiccator such as the jar-desiccator (above), or allowed to air dry either in a room with still air, or in the refrigerator in porous paper (such as a coffee filter). If seeds start to mildew, the seeds will be so loaded with live spores that they will become difficult or impossible to disinfect effectively.
Orchid seeds must be shipped only when dry.
We have found that more seeds are lost to improper shipping and storage of orchid seeds than for any other reason. Seeds that are shipped either in capsules that broke before or during shipping, or seeds that were too moist when they were shipped, will invariably spoil in transit. Remember that disinfection is a reduction in the number of bacteria and fungi; and if there are a million spores to disinfect, it is a thousand times tougher than when there are only a thousand spores present. Seeds should never be shipped in plastic unless they have had several weeks to equilibrate their moisture with desiccant (calcium chloride slurry). Otherwise, they should be shipped in “pocket” coffee filters or glassine weigh papers.
Seeds should be collected and stored on clean, dry paper.
Glassine weigh papers are very good, and inexpensive. They allow for virtually 100% of the seeds to be recovered. If collecting seeds, regular copier paper is fine, except for small capsules (which do not have many seeds to begin with). White paper has been cooked, bleached, and cut so fast that it is virtually sterile. Every time you touch it with your hands, it collects more bacteria and fungi, which will rub off on seeds. Using “greasy” paper like newspaper, etc. is even worse; the inks make it more difficult to disinfect seeds.
Maintain the proper labels with seeds. If the seeds are not identified, they are virtually without value. Confusing or poorly written labels- or none at all- make the situation far worse.