Micro forest

The little pawpaw seedlings are now a micro forest. They have years of growth ahead before becoming a mature trees, but I appreciate the fact that they have germinated and are growing.  Some seedlings have begun developing vegetative buds in the leaf axils.

Officially seedlings

My little pawpaws have broken through the soil.  Most are now erect and starting to grow their first leaves. 

Pushy Pawpaws

The first seedlings are pushing through the soil.  The exposed stems are red.

Breaking through

It's been a month and one week since I took the asimina triloba seeds out of cold storage.  The seeds are trying to push up through the soil.  I predict by this time next week some of the plants will have broken through. This gives me 2-2.5 months to get them under grow lights and bulk them up.  My hope is that they will be large enough to sell by the first week of April.

I definitely need to leave all seeds in cold storage at least 90 days next year.  The germination rate of the earlier seeds with only 75 days stratification is significantly lower.

Pawpaw Seed Germiation

It has been almost a month since I put all my pawpaw seeds in tree pots with soil.  Although they were all placed in the tree pots at the same time, they were not taken out of cold storage at the same time.  The seeds were in cold storage anywhere from 75 to 90 days.  The first seeds to germinate were the ones removed from cold storage first.  However these seeds seem a little sluggish to germinate.  Five days after the first set of seeds started to germinate, the seeds that were left in the refrigerator for the full 90 days started to burst forth.  Now the 90-day seeds seem to have out-germinated the 75 day seeds.  This leads me to conclude that the key factor to germination speed is cold storage.  The longer the seeds are in cold storage, the faster they seem to germinate (up to a point).  Of course I do not advocate leaving seeds in the refrigerator for 5 years to speed up the germination process.

Additionally, the 90-day seeds seemed to have germinated well even though the seed coat was left intact.  I don't know how crucial the removal of the seed coat is to germination.  I think a properly stratified seed with optimal environmental conditions will germinate just fine with or without the seed coat.  I may do some experiments next year with seed coat v.s. Non seed coat germination.  But I believe I will leave most of the seed coats on for next year's germination.

In summary, thus far my best practices for asimina triloba seed germination are as follows.

1. Immediately clean seeds removed from fruit.

2. Immediately wrap seeds in moist paper towel.

3. Double-bag seeds/paper towel in plastic food storage bag to conserve moisture.

4.  Leave seeds in refrigerator for 90 days minimum, changing the paper towel every few weeks to prevent mold and fungus.

5.  Place seeds in 10-inch tree pots containing moist soil.

6.  Keep tree pots in a plastic tote with lid to increase moisture and humidity.

Asimina Seed Germination Observations

I checked on my pawpaw seeds again.  Before, only 3 seeds had germinated.  Today, there were 9 germinated seeds.  All but one of the germinated seeds had the seed coat removed.  This makes me think that removing the seed coat hastens germination.  Lord willing, next year I can do some controlled experiments or trials with germination of seeds without the seed coat versus seeds with the seed coat.  I have concluded that cold storage for 82 or more days is sufficient to break seed dormancy.  Wrapping the seed in a wet paper towel and then a plastic bag is sufficient to maintain the moisture levels of the seed while in cold storage.  The sweet spot for seed germination is 37 to forty days, at least for seeds without a seed coat.  The roots have grown 1 inch in 2 days.  I wonder when the plants will push through the ground.

Asimina Triloba Germination Evidence

Three of my pawpaw seeds have started to germinate.  I had removed the seed coat of two of the seeds.  The other seed had its seed coat fully intact, but the germinating root clearly cracked through the coat.  I took the pawpaw seeds out of cold storage at different intervals, so I assume that these seeds are the ones removed from cold storage on November 13, the next November 22, the next November 28, and the last December 3.  By my calculations, these seeds require a minimum of 35-45 days to show the slightest sign of germination.  My research indicates the seed will grow a long root first.  I predict that will take until January 20.  Then it should start to push the stem.  By about mid February, I should see the plant poking through the ground.  Once the plants break though the ground, I will place them by a sunny window or under a grow light.  I know that seedling pawpaws cannot tolerate strong light, but  the window filters out some of the sun, so I think it will be okay.  From February to April, I hope to get them to grow several inches so that they are large enough to sell.  I hope to list the little plants on EBay or Amazon in April.  The youngest batch will be about 3 weeks behind the most mature batch.