How to maximize your germination success with the Baggie Sowing technique.
I want to thank “Rob’s Plants” for the idea of baggie sowing. Before this technique, my sowing involved trays, cells, and pots AND lots and lots of medium. Then you have to ensure the sown seeds receive the correct stratification protocols to break dormancy. Hardware cloth covered nearly everything to protect precious seed from rodents and foraging songbirds. It was a chore. Germination success was less than stellar.
Now we nearly baggie sow everything but fine seed that is difficult to transfer by hand. We have learned to alter the medium to suit the seed type such as conifers do very well in finely milled moist bark mulch or chopped pine needles instead of the usual medium of 3 parts screened peat moss, 1/2 part sieved perlite and 1/2 part silica filter sand (we use Lane Mountain 20-30 silica sand).
How to: soak seeds so they are properly hydrated. Its better to have slightly less fully hydrated seed than water logged seed as this might prove fatal to the embryo. The amount of seed you place in a resealable baggie is dependent upon the quantity and size of the seed as it is preferable that seed to not touch each other. Mix seed and moist medium in a bowl. If seed are properly separated, place it in a labeled resealable freezer type bag. Information should include species/variety, date, and hydration time (ie 24hr soak). Depending on the species, begin cold or warm stratification cycle(s). Mark you calendar as well. Don’t forget to check your bag(s) about once a week as we are surprised by early spouting seed.
Many species have complicated germination protocols with prolonged cold, repeated warm/cold cycles, or to mimic the heat within a mastodon’s digestive tract (think Gymnocladus). Genus such as Stewartia need repeated warm/cold stratification cycles. Doing this using pots and giving germination protocols are difficult. No wonder they are so expensive. With baggie sowing, its as easy as taking the bag in and out of the fridge. Transplant seedlings and continue the regimen.
We place our stratified Asimina triloba seed on gentle warmth in February. I read other growers complaining that their sown seed is just breaking the soil surface in June whereas our seedlings are pushing out their next set of true leaves. Timing. Timing is everything. Getting a few extra weeks or months of growth can make a huge difference is over winter hardiness. }}You might have noticed some of the baggie sown veggie pics such as Desi summer squash, asparagus and a few others where we use moist coffee filters instead of medium. By giving these uninterrupted warmth, germination can happen in days with a greater germination rate.
As I write this on Dec 1, 2020, we have Nyssa sylvatica and Cornus mas “Redstone” under the grow lights. These seedling will be easily twice the size of their spring germinated kin by the end of next summer. Soon they will be joined by various Magnolia species.