I have struggled growing pawpaw trees in my extremely heavy clay soil. I think this may be due to the pawpaws I purchased having very little fibrous roots. My potted pawpaw have done wonderfully. I think this is partly due to being able to move them to more shaded areas during the heat of the summer. Can anyone offer any insight on the effects of a fabric pot on the root system of pawpaws? I have some pawpaws currently growing in 7 gallon knock-off fabric pots. I plan to graft them, so I don’t want to pull them out to inspect the roots. I do have some pawpaw that have made it in my heavy soil, but I feel having a dense fibrous roots system will make these trees perform much better.
Not shure about the fabric pots?
7gal seems large .
I use the tree pots 4x13 stuewe and sons ,with good results.
Most important is to provide some shade until they are about 3yrs old.
And mulch !
There are a few on here that use Root Maker pots and bags. I think @forestandfarm is one. There is a whole system of moving the trees up in sizes as they grow. I gather you have to move up sizes as otherwise you don’t get the intended air pruning of the roots that helps force the growth of the fibrous roots. https://rootmaker.com/rootmaker-system
I started a bunch of pawpaw from seed. The way an air pruning system works is that you start with a small air pruning container. This prunes the tap root which causes upstream branching. Studies show that most of the branching occurs in the first 4" before the prune. These secondary roots then prune when they hit the air as well. You use a very well drained mix like Promix with these containers which has lots of small voids in it. The roots begin filling these voids. When you first plant in these and water them, the water almost immediately drains out the bottom. As the roots fill the container, they become hard to water. Water just seems to sit on the container and it takes a long time adding a little water at a time to saturate it and get water to come out the bottom. This indicate the container is full and it is time to transplant to the next container.
When you transplant you want a container that allows for no more than 4" in all directions since that is where most of the branching will occur when those secondary and tertiary roots eventually get pruned.
I have the most success starting trees from seed under lights in the winter and then transplanting them from 18s to 1 gal Rootbuilder II containers at 12 to 16 weeks. In late spring (after acclimating the trees to my deck), I transplant a second time to 3 gal Rootubilder II containers. I either plant the seedlings from 3 gals to the field in fall or I over winter them in a cold room and plant them in early spring.
This system works great for most of the trees I’ve planted. This includes chestnuts, Allegheny chinquipins, pear, apple, jujube (started from root cuttings), Filberts, Dwarf Chinquapin Oaks, and more. The jury is still out on pawpaw. I have heavy clay as well.
Because pawpaw are photosensitive when young, I kept my pawpaws on my lower deck that is shaded for 2 growing seasons. They did really well growing in the containers. I planted them in full sun in the field last spring. Most leafed out well. Some went dormant in the summer. They had no protection from deer but I don’t see much evidence of deer browsing them. Some held their leaves until this fall and went dormant when expected.
Next spring will tell how many survived. My trees are in a wildlife setting and get zero care in the field. They all slow down when they are surviving on the nutrition in my poor native soils, but they do much better than bare root trees.
All great answers to your question Bambooman.
I’ll add one thing… pawpaw transplanted at anytime to full sun will need ongoing sun protection for at least two years. I’m not talking about a 5’ tall tree that’s 3’ wide but any in the 3-gallon range of roots. Shading is key.
Pawpaw are understory trees in natural habitats but do best when grown in full sun. 2 years of shading is good but 3 years of shading in a full sun environment is better for establishment.
You’ve nailed it on the head about fibrous roots as have the other posters, as-well. Whether pawpaws or anything… it’s proven. I’m in full agreeance also with @Hillbillyhort that long Stuewe pots are just as excellent as root-building products. I’ve seen both methods first hand and both transplant very well to the full sun or partly shaded/fully shaded, landscape. The key to Steuwe tree pots is to notice when the roots have made their way to the bottom of the pot and to move them from that container then either to the landscape or to a larger width/length treepot or fabric pot. The Steuwe mini-tree-pot is great for starting pawpaw seeds. Also, the larger Steuwe tree pot is great to transplant 18-cell rootmaker’s into.
Heavy clay will always be a hindrance to success and losses should be expected.
One more hint when planting any rootmaker (or similar) type tree into heavy clay: The medium I talked about in my previous post is very porous. When that medium is put into heavy clay, you can create a pond and drown the rootball. Conversely, during dry times, clay will retain water much better and the rootball can dry out. I finally found a method for field planting rootmaker trees that works pretty well.
- Select a planting location that is not in a dip where groundwater will drain into the hole.
- I use a tractor auger that is very close to the size of the rootball. Rootbuilder II contianers unwrap and the entire rootball comes out intact.
- I auger a deep hole, several feet.
- I back fill the hole with amended soil that is well drained. I even include some quarry stone to ensure good drainage and that it won’t compact over time. I fill the hole so that when I add the root ball, the top 1" is above grade.
- I pack the amended soil to ensure it won’t further compress over time. I then hand rake the inside of the remaining hole to ensure the auger did not cause glazing.
- I remove the RB2 container and soak the rootball and place it in the hole. If there is any gap around the rootball, I fill it with native clay.
- I use the extracted clay to make a ramp up to and over the medium. This helps prevent ground water draining into the hole and helps stop water from evaporating from the medium.
- I then use h2O and gas permeable landscape material and cover it with quarry stone. I find quarry stone deters rodents from nesting and is permanent unlike organic mulch.
The theory behind this method:
In my area we get ample rain in the spring and fall but we can have dry periods in the summer. The deep amended hole and care to avoid ground water drainage causes any ponding to occur below the rootball. Trees are smart about growing roots into a water source but most can handle inundation. The reason the auger is very close to the size of the container is that I want the lateral roots to have a very short distance to grow to enter the native clay. The native clay retains water much better during summer dry periods and once the lateral roots get into the clay they can survive the dry period much better.
Again, once planted my field trees don’t get any care. If you can provide supplemental water, this last aspect is less important.