Different types of germination inhibitors can be overcome in different ways.
Some desert plants, as well as many other plant seeds, have some type of chemical inhibitor built into the seeds genetic structure which requires stratification in order to germinate.
The chemical inhibotor keeps the plants from germinating when conditions are unfavorable to the growth and survival of seedlings, and there are several types of internal dormancy.
One type is called “shallow” dormancy. The seeds of many vegetable plants fall into this category. The dormancy-disabling chemical simply disappears with dry storage. You don’t need to treat this kind of dormancy.
But another kind of internal dormancy needs special treatment to germinate. These types of seeds won’t germinate unless they experience a specific period of moist pre-chilling (called cold stratification), or moist warm periods, or even both.
To cold-stratify a seed, mix seeds with an equal volume of moist peat moss, or sand. Put them in a closed container and store them in a refrigerator at around 40 degrees F. Check the container regularly to make sure the seeds are moist, but not wet.
By sowing seeds (or bulbs) in the fall, in areas with cold winters, you can avoid the issue of cold stratification.
Warm stratification is very much like cold stratification, except the seeds are kept at temperatures between 68 and 86 degrees F.
Everything depends, of course, on the species. Check reference guides or gardening books to find out which species needs what kind of stratification.
