Pawpaws 2024

First, I hope it is neither presumptuous nor premature for me to create this thread. I observe that most of the prior pawpaw threads are created at some point in the spring once flowering begins to occur, but it is New Years Day, and I have a seed-starting question.

I have some seeds — scrubbed, soaked in a dilute bleach mixture, wrapped in wet paper towels, briefly and inexplicably frozen within those towels when nothing else in the fridge froze but then thawed, changed with new paper towels at first hint of mildew — in the fridge since early October, so I am coming into the 90-120 day window. I have consulted @Blake’s book, but there were a few questions I had from others who have started pawpaws from seed.

  1. I see a lot of people talking about using tall, narrow tree-tubes to allow the tap-root to grow while not wasting soil or taking up too much horizontal space (e.g. in my 5 gallon buckets). Is there a recommended brand/thing to search for/style?
  2. How warm do pawpaw seeds need to be for optimal germination after stratification? I have a little grow-light setup in a chilly basement to overwinter some big plants I don’t have room for in the house, but I don’t know if it’s more like peppers, where I start them warm as possible (using heating mats).
  3. I’ve seen a wide range of soil recommendations that seem to change over time and I would like to know the current best practices, and also how to think about watering the soil (and how that might relate to temperature)

I want to start these seeds just to see if I can (will eventually plant, of course, if they germinate) and will probably also try to buy some grafted seedlings from Blake or @Buzzferver once the weather warms up a bit and I’ve selected a planting site…

Happy new year everyone!

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It’s not going to be helpful to try starting them today (except for those in the Southern Hemisphere). But, indoors or in a heated greenhouse (and using something for shade)…you could get a jump on spring I suppose.
I just use a one gallon pot and about 3 seed to the pot…but sometimes the root does circle the pot even the first year. I plant in pots in shade of trees or on north side of a building.
Am sure you’ll get additional advice here.

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@Petey
To curtail root circling, use a ribbed tree pot such as Stuewe 9 x 15 R.

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I’ve had satisfactory results,using 2 liter plastic drink bottles,with the tops cut off,near the neck.Some holes were punched on the sides,close to the bottom.
They were put inside a Rubbermade type container,maybe a dozen,with a heat mat.The cover of tub was used,that kept it quite humid,which they probably like.This setup was inside my house.80F is a nice temperature.No light is necessary,until they start sprouting.Then an ordinary two bulb,fluorescent lamp was placed above them,about 12 inches away.

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Thanks Richard — I had heard of these and will look for some.

@BlueBerry — are you saying that heat (or room temp) is good, light unnecessary for the first few months of below-ground growth described by Blake?

I was a little unsure on how many seeds to put in each pot — I have, I don’t know, 20 seeds, and I don’t know if I want or have space for 20 pots, but I’ve heard that pawpaws don’t take well to transplantation, so I didn’t want to start them all in very small pots and then try to transplant to larger ones if they lived (because that might kill them)?

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They like summer kind of temperature…like tomato and pumpkin sort of temperatures…so don’t expect your seeds to germinate outdoors until nights are comfy and days quite hot. (And, yes, they’ll like room temperature and even a closet is ok until leaves appear.) It can take 30 to 60 days before you see leaves as the root does it’s thing first (to some extent you see this in acorns and hickory etc). So you eventually see leaves and by then the root’ll be 3 to 8 inches long probably. Sort of like a carrot or dandelion, not a lot of little fuzzy roots, just a main root.

You can transplant young seedlings just fine. If you plant in May in pots outdoors, and put several seeds in a pot…by late July you’ll have little baby plants. Not every seed germinates. And about 10% take an additional cold period and eventually some that didn’t come up may do so a year later.

In any case, if you had 3 or 4 little ones in a pot, carefully dumping the pot so as not to break the tiny plants, you can ‘bare root’ them and re-pot one to a pot…or plant out.
(Just remember, as you mentioned Blake said, they can’t take much sun so shade cloth or in the shade of larger trees or a briar thicket…something must shade the babies for at least a year. In the sun they may not come up…and if they do the full sun kills them. Dappled shade under a tree they can handle.) Or full shade on shady side of a building.

You can have them in full sun once they’re older.

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If you are just buying a few tree pots, you can get them through Green House Megastore. If you need a bunch getting direct from Stuewe & Sons give you a lot more choices. I think the 4X14 are a good option if you are just growing them one year then planting out. You can fit 9 in a milk crate to make them easier to carry around and to keep them from falling over, etc.

You can plant them directly into the tree pots, but I imagine it is hard to get even heat to them all the way up at the top of those tall pots.

I started 3 pounds of KSU seed last year that I got from Cliff England. Since I had so many of them, after stratifying I put them into 10X20 flats on a heat mat kept around 83-85 degrees. This made it easier to get them all heated and germinating. I simply put a little more than an inch of ProMix in the bottom of each flat spread out the seeds so they weren’t touching and then filled the rest of the tray to the top and pressed it down firmly . The flats had holes for drainage and I kept humidity domes on top to make sure the soil didn’t dry out from the heat mats as well as just to keep the soil temps more consistent. I think I divided the 3lbs of seed into 3 flats (1 pound per flat), but it may have even been 4.

After a month or so the majority had germinated and were sending down good roots - a few were being pushed up out of the soil which made it obvious, but I gently dug a few others out to check them. There was a little bit of a J shape starting when I transplanted them due to the shallow trays, but not enough that it worried me. Here they are being planted into an air pruning bed. I just cut the sides of the trays and folded them down to make it easy to get the seedlings out.



They survived with no ill effects from being transplanted after germination and did great. Here is what they looked like a couple of months after transplanting.

I definitely recommend starting them inside and getting a jump start on the season since they grow slow and will also germinate quite slowly outside in the colder soil. Starting outside some may barely get above the soil before fall.

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@zendog
Those “trays” sold by Greenhouse Megastore are the wrong size. Even in the photo you can see that only the pots in the center are vertical.

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@Richard Yes, and very expensive for what they are. I’m pretty sure they are the ones from Steuwe, but even so I find old milk crates work great and there is enough space that I can keep them all upright so that they will be easier to water evenly.

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@zendog If I find my way back out there again I have some frozen pulp from my seedlings I would like your opinion on. I have a white flesh one that I’m really excited about, but need some taste testers before I promote it as something worthwhile for people to graft. Really nice vanilla marshmellow flavor.

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Steuwe sells mold-form trays, crates, and “kits” containing pots and crates/trays of the correct size.

Maybe I’m mistaken, but the trays look the same to me:

@zendog
Yes, they do sell generic trays. But if you are going to pay for shipping, wouldn’t you rather order these:

These are teriffic pots. Still, you have to admit he did good using the ones he had.

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I understand air pruning beds work particularly well for paw paws since you can unscrew them and the soil falls away from the roots. Ive had good luck with the stuewe d40 deepots. https://stuewe.com/product/d20k40/
Also, 6 gallon buckets work well. Theyre deeper than 5 gallon and can handle uowards of 15 seeds/ IME

So I guess I’m still confused about the “multiple seeds per pot” thing, in this case (maybe I’m too anchored on the “pawpaws are delicate babies” thing).

If I put, say, 10 seeds in a 5 gallon bucket full of soil, and then let them germinate, and then in a few months gently tip them out and see which ones did, and then move those alive ones to the tall tree pots, is that a potentially good solution? Somewhat more economical than buying a bunch of tree pots for seeds that might not germinate, at no more risk to the seeds?

Small treepots are for raising seedlings, cuttings, and airlayers into saplings.

I grow a couple hundred seedlings a year by planting fabric pots full of rotten fruit in the fall. I keep my fabric pots(growbags) in the shade of a mulberry tree because they will burn when they first emerge. They usually sprout around the summer solstice, and later in the fall after the harvest I dump the soil out of the fabric pots. The roots usually hold tight to the fabric and once the soil is out of the way its easy to put them into treepots or 1-3 gallon pots. I am in 6b/7a near Louisville KY, and I do not protect them from freezing temps(lows of -7 last winter). Pawpaws can be delicate but if you know how to work with them they are very hardy. Hope this helps. I don’t believe in growing plants that are not vigorous enough to survive this treatment.

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I tried planting in August and September seedlings had a lot of losses going through the following winter. But, if they get a couple months to get going…they’ll survive even -19 at least in pots outdoors.

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That is good to know, thanks!

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