Maintaining Seed Viability
Non-viable seeds are often the cause of failure during sowing. There are many causes of poor viability.
- A seed may never have been viable in the first place. Poor pollination causes many seeds to look good on the outside but be empty inside.
- Insects or disease may have attacked a viable seed.
- It may not have been stored properly to maintain viability.
- It is just too old and has lost its vigor.
At Sheffield's, we check all seed to ensure that it is viable.
There are two very simple tests that work quite well to quickly check quality.
1. The float test… Many times viable seeds can be separated from non-viable seed by floating in water.
If you float seed in water and some floats and some sinks, try cutting some of the floaters and also some of the sinkers.
If the floaters look empty or bad and the sinkers look full and good then you know this is a good method to easily separate out the bad seeds.
This method works well for many species of oak acorns that do not hold their caps. Occasionally in a dry year, good seed will float. You need to cut some floaters
to see if this method should be used.
2. The cut test….Like the float test, this method is not 100% accurate, but one thing it will tell you for sure is if a seed is definitely bad. If you cut a seed and it is hollow inside,
with no visible embryo or endosperm, it is more than likely not going to germinate. Of course, the cut test is a destructive test so do not use it on seeds where you have a very limited amount, or can't waste any.
Most seeds keep better at cool or cold temperatures. There are species from the tropical rainforests that do not keep well at all, such as Cocoa. However, most seeds from colder or drier climates store relatively well at refrigerator temperature, for those that can't be dried down such as Oaks and Chestnuts. Or frozen, if they can be dried to 10% moisture content or less such as Pines and Firs.
