Jafar, I've seen a number of comments in different places about pawpaws not growing fast.  I wonder if, rather than it being the cultivar, or the orchardist, if it's the rootstocks?

I read this about chestnuts.  In some writings, a chestnut cultivar should be grafted onto its own seedling, otherwise the tree might not thrive, or the graft might not takes, or it will take but die later on.  I think a lot more is known about chestnuts than about pawpaws, but what if something similar is happening?  Especially in a climate that might be outside the pawpaw's provenance?

I had a Rebecca's gold that never got above about 2 feet tall, then died.  I have Mango, which is not in an ideal spot, but is only about 3 feet tall, and has bloomed for three years.  It will get some coddling this year, and I already started by removing competition and doing the first fertilizing.  Meanwhile, I have the two that are about 8 or 9 feet tall - Sunflower and NC1, and one younger one that is 5 feet tall - Allegheney.

Since pawpaws are grafted onto seedlings of who knows what parentage, maybe those random seedling rootstocks are part of the challenge.

Two of my trees have suckers growing put of the rootstocks.  Im letting one grow, from each, as kind of a backup and as a pollinator.  That will make each into a 2-trunk, 2-variety tree.  Those suckers are growing faster than the original trees, but then the roots have been growing for a longer time so they get a head start.

My pawpaw seeds are not sprouting yet.  I look every day.  Maybe the won't!  But then maybe a watched pawpaw seed never sprouts,

My Sunflower is about 8 years old and 11-2=9 feet high. Bought it at about 2 feet high so 9/8 = a foot a year. So mine have grown pretty good here in the NW. My Overleese is growing pretty close to that. They seem to blossom about 5 years after planting. The problem is that the after pollination most of the fruit dies and falls off. perhaps they are not getting polinated although I pollinated this year with a q-tip. 8 blossoms on the Overleese and no fruit. last year one blossom and this year maybe 8. Sunflower, which is older, had almost 40 blossoms this year. last year it produced one stunted fruit. This year I have 4 fruit which beats the one last year. I was thinking of topping the tree and hoping that the tree would send branchs out to make a leafier plant to make it look more tropical. Also,  maybe the plant would send more energy into making fruit.

Kentucky State U has a pawpaw program.  Sheri Crabtree of KSU knows a lot about pawpaws and will answer questions to the best of her knowledge.  She said if size is a concern, pruning to a modified central leader works well. 

I have 2 seedling pawpaws I planted spring 2013.  One was damaged and this set it back 2 seasons.  The other first bloomed 2017 and fruited 2018.  Now in its sixth year, this tree has set a bumper crop.  The other first flowered this year. I live NE of Oregon City.  Since the first one fruited without another pawpaw within miles, I must assume it is self fertile.  I carefully saved seed and refrigerated in peat moss for 5-6 mos. Planted 4/21,and they finally popped out a week ago.  I wanted some seedlings from the self fertile cultivar, and it looks like I will have 17 coming up in 14"tree pots to accommodate the deep taproot.  I had given up.  10 wks from planting to sprout.

This year, both trees bloomed.  I hand-pollinated. Stigma is mature in the almost unopened blossom.  Pollen is mature in the older flowers.  There are always some young blossoms and mature blossoms on both trees. The lag between female and male development in the flower is why pawpaw are not thought to be self fertile.  The hand pollination worked.  My smaller tree is developing a couple dozen fruit, The older one has around 100. These trees flowered first within 4 years, fruited first in the fifth year.  Both are around 12' tall.  I made my first pruning cuts in March.  I hate to do anything that might harm productivity, so I am going slow.  If I could just let them grow, I would, but I am afraid of shading the persimmon,pear and cherry behind.  Someone suggested not pruning at all, and to make sure that the fruit will have a soft landing when they fall.  One thing I learned from my first crop last year is that fruit must be harvested dead ripe and eaten immediately.  The only way to be sure it's ripe is if it falls from the tree. 

@quokka: With pawpaws, like almost any other sun intolerant tree, needs shade along the stem during hot weather. It's been published a long time ago on keeping sun collars on young pawpaw trees until the leaf canopy develops sufficiently well enough to remove the sun collars. The omission there-of can even kill the younger trees no matter how much moisture they receive. The original write-up about this has actually helped me mature not only my own pawpaws but understand how heat and dehydration stress in lower vascular tissues in trees in Alaska that must cope the lack of thawed water (not heat) can limit or kill trees.

My pawpaws have not been all that rewarding either.  I have enough room, so I just let them do their own thing now.  Only two are the original graft - NC-1 and an unhappy Mango.  The rootstock that used to be Sunflower is almost as big (7 or 8 feet?  my guess).  If it blooms next year, we'll see.  I have seedlings, all of 6 inches tall.