Growing sun-tolerant paw-paw seedlings -- all it takes is a 50% sacrifice?

This post is occasioned by me having apparently lost all of last year's pawpaw seedlings in poorly-protected pots when we broke all cold records last winter.  Although several permies have generously shared seeds with me in the past, I decided to go for some instant gratification and order stratified seed from an Etsy seller.  Which reminded me of the usual dilemma: all sources say that the pawpaw tree will produce best in full sun, but the seedlings need to be protected from full sun or they will die.  Tricky, and at best a huge pain in the ass.

Thus you will imagine my interest in a factual tidbit on the recent Partisan Gardens podcast The Dystopic And Exceptional Pawpaw.  At about 25:30, one of their guests can be heard to say that the Indiana State Nursery simply plants all their pawpaw seeds in full sun and expects a 50% die-off rate, leaving them with fully sun-tolerant seedlings to distribute.

My jaw dropped when I heard this. The muchly-advertised habit of pawpaw seedlings to shrivel and die in full sun only affects fifty percent of them?  How come nobody ever told me this?  It's always treated as a 100% universal trait!

Sure, pawpaw seeds are expensive if you buy them in small quantities.  It's not hard to find sellers asking a buck a seed.  But what do shade cloths, tomato cages, and our time cost?  

To me this was revelatory.  Just plant twice as many seeds!  Boom, problem solved.

But it is true?  

I'm curious what other people think based on your own experience.  

both a friend and i have grown pawpaws from seed in full-sun nursery beds. i think 50% die-off is overstated, i don’t think fewer than 75% of mine made it. i have frequently said that i suspect the ‘common knowledge’ of young pawpaw seedlings needing shade was parroted more from earlier sources than from experience.

My only experience with growing them is growing them under shade for the first couple years, and then removing it when they are older.  I put four posts in the ground and put an old shirt over it, directly over the plant.  It worked well, but I don't know the answer to your 50% die-off question.  As it is, I've lost all mine to cold except one that I'm still hoping may leaf out this year.  So far, it doesn't look too promising.  We had a pretty mild winter too, so if my last one dies this year, I'm afraid I'm giving up.  That saddens me because, while I've never tasted one, they sound delicious.

greg mosser wrote:both a friend and i have grown pawpaws from seed in full-sun nursery beds. i think 50% die-off is overstated, i don’t think less than 75% of mine made it. i have frequently said that i suspect the ‘common knowledge’ of young pawpaw seedlings needing shade was parroted more from earlier sources than from experience.

That may be true, but mine did sun burn badly when I didn't cover them.  I didn't wait to see if they would die, but the leaves burned completely white and it didn't seem like they were going to make it.

trace, did those plants leaf out under cover and then get uncovered, or were they out in the sun before they leafed out?

i wonder if different populations from different places will act differently....

greg mosser wrote:
i wonder if different populations from different places will act differently....

This is a very interesting question!  Just putting this here because I won't remember the information in a year or two when it becomes clear how my seedlings fared, the seeds I planted today were from an Etsy seller in Indiana selling a mix of seeds out of the fruit of her yard trees, types given as "Sunflower", "Taylor" and "variegated" -- whatever that last is supposed to mean.  (I think it means she has multiple different trees planted from wild or unknown sources, but I'm just guessing.)

greg mosser wrote:trace, did those plants leaf out under cover and then get uncovered, or were they out in the sun before they leafed out?

i wonder if different populations from different places will act differently....

That's a good question Greg, but I don't know.  They may very well have been under cover.  I know I bought them as trees rather than growing them from seed.

I have an area that is large enough.  Maybe if I can get a deal on some seeds, I'll plant 20 or so and see what happens.

gotcha. i’m wondering if the effect is more akin to not being hardened off than something particular to pawpaws - though i wouldn’t be surprised if pawpaws were more susceptible to injury through incomplete hardening off than other trees.

Not having any pawpaw's:

I suspect it is a big difference whether you direct seed into full sun vs. transplant from nursery.

So when posting your experience, please include this data.

Another generally known "fact" about pawpaw is that they do not transplant well at all. Reportedly they have a very large taproot and it's quite difficult to dig up a seedling without cutting that taproot, after which the plant is Doomed! Doomed I tell you! I'm not sure how accurate this is, and I'm not sure what happens when you start your seed in a pot and transplant from there. Is the taproot stunted from being potted? Is that a problem? I don't know.

Our experience with pawpaw on our site is that we have planted numerous seeds in the fall, being careful not to let them dry out before planting (another reported issue with pawpaw, if the seed dries, it's done - maybe?) and have not yet seen a single seedling appear. I remain hopeful, I've heard some stories about them taking a long time to germinate (like over a year). On our site it's hard to find spots with "too much sun" because we're fully forested. I'm insinuating food elements into an existing forest. It's not the typical paradigm.

Some of the issue is the intensity of the sun.  In my location (North Alabama) I noticed sunburn on my leaves and after spending $ on cultivars I put a wire cage around them and 50% shade cloth for shade from noon through the rest of the day.  after 2 years I take off the shade cloth.
I am growing around 90 seedlings and will cover them as soon as I see sunburn but right now they are so close together in tree pots that each only gets some of the sun.  
I transplanted 3 wild ones onto my land, that survived.  The trick is keep the root hairs intact.   The tap root can be severed and the tree survives but the root hairs are critical.

Here in Indiana, our state nursery sells pawpaws in packs of 100, so they grow a lot of pawpaws. One year when I was at the state nursery and asked the forester how they protected their young pawpaw seedlings from the intense sun, and they replied that they just grow them in full sun.

In the past, I had tried various methods of shading pawpaws, but these days I just plant them in full sun right away. I have found that a bit of extra water often helps, and my survival rate isn't fantastic (a bit north of 50%), but at 35 cents a tree I'm fine with half of them dying.