Instructions for sowing seeds

Instructions for sowing seeds

What is stratification?

Many seeds mature on the plant in the Fall. If they were to germinate at that time the Winter would kill them. Nature has given them a built in protection against this by requiring that they go through a period of cold temperature prior to germination. This requirement can be met in two ways. If you live in a northern climate and you are confident that the outdoor temperature will be below 40 degrees Fahrenheit for the 30, 60 or 90 days that we say the seed requires for cold stratification, than the seed can be sown in seed beds outside in the fall, mulched heavily to prevent soil heaving and then remove most of the mulch in the Spring to allow the seed to germinate. The other way is to artificially condition the seed by soaking it in water and then drain the water and mix with an equal volume of moist perlite, peat moss etc. Place the seed in the refrigerator for the required time prior to sowing. The trickiest part of this is getting the moisture right. You need the stratification media to be moist but not wet. If you can ring water out of it then it is too wet. Mix the seed with this moist media and place it in a sealed plastic bag in the refrigerator. Check it every two weeks or so to make sure that it is the proper moisture and that the seeds are not molding or beginning to germinate. If there is any sign of mold they should be soaked in a solution of 3 parts water to 2 parts bleach then rinsed with clean water and put back into Stratification. If they are beginning to germinate they can be sown if the timing is right or kept as cold as possible (above freezing) until such time as you can sow them.

What is Scarification?

Some of the seeds that we sell have hard seed coats that allow them to sit in the ground for many years waiting for the proper conditions to come along for germination. This adaptation is particularly true for species that come from dry environments. These seeds will not germinate until water can penetrate the seed coat. To facilitate this the seed coat needs to be softened to allow water to penetrate. Our recommendations for scarification are based on the average requirement for each species. It is safest to start with the least harmful method and work up from there. A cold water soak for a short time duration is probably the least harmful. This would be followed by a longer time duration and then warmer water up to the boiling point. Whenever mention is made of soaking in hot water, etc. It means to initially subject the seed to the hot water and then to let it cool in that water. DO NOT keep the water hot for 24 hours, etc. After a treatment has been finished a few seeds should be cut to see if they have imbibed (taken up water). Continue the treatments until you notice that the seeds have indeed imbibed. 

If boiling water has been tried and the seeds have still not imbibed, concentrated sulfuric acid or mechanical scarification must be used. For the acid treatment seeds are placed in a glass container and covered with sulfuric acid. The seeds are gently stirred and allowed to soak for 10 minutes to several hours, depending on the species. When the seed coat has been modified (thinned), the seeds are removed, washed, and sown. Sulfuric acid can, however, be very dangerous for an inexperienced individual and should be used with extreme caution! Proper protective clothing and eye protection must be worn. Vinegar is safer (but less effective treatment) and can be used for species that do not have an extremely hard seed coat; the technique is the same as with sulfuric acid.

For mechanical scarification, seed coats can also be filed with a metal file, rubbed with sandpaper, nicked with a knife, or cracked gently with a hammer to weaken the seed coat.

Following scarification, the seeds should be dull in appearance, but not deeply pitted or cracked as to damage the embryo. Scarified seeds do not store well and should be planted as soon as possible after treatment.