Randy Knight follow up Question and Answer on sawdust healing bed

[PutItInTheGround]

I know Randy through one degree of separation and he was kind enough to answer a question I sent him. I want everyone at Mirai to benefit from his wisdom so here is our brief Q&A.

Eric:
First off, I can’t thank you enough for your stream today. Sooo much information. I’ve been having low success rate collecting my field grown trees. I think due to clay soil and lack of capillary roots so I want to do the sawdust bed method. My field is in Pennsylvania at my parent’s property so completely different back on the east coast and I bring the trees to my home in Colorado. I know, I should just be collecting in Colorado but I love growing in the field.

I want the higher success rate but I fear the cold and wind of Colorado. I live in Golden Colorado on the front range. Winds can be brutal especially in the winter and spring. Would it be an issue to have trees exposed all winter without protection in the sawdust bed? I’m thinking red japanese maples and other non native species could have considerable die back or may just plain die if exposed to Colorado winter. Might it be good to plant the tree in a porous container filled with sawdust, which is then heeled into a sawdust bed? Then when the winter freeze comes this would enable me to pull it out of the bed and into a winter protection such as a garage or cold frame structure?

Maybe this type of solution would be good? I’m just thinking out loud and would greatly appreciate any thoughts you have on this.

Randy:
Hi Eric.

Thanks for the kind words.

Yes the winter/winds will kill the Japanese maples for sure. Your environment is tough on non native deciduous as you know.

Spring sun on the south side of the deciduous trunks can be damaging as well. Warm spring sun gets the juices flowing in the cambium on the sun exposed side first. Then overnight freezes kill the bark.

Summer wind will also be a potential problem. Think about some type of wind break. The issue will always be dessication.

Your idea of a porous container in the sawdust bed could work. Anderson flat or similar probably would work best. Colander will not work nearly as well. Not enough close ground contact I don’t think.

Whatever you use, make sure it rests directly on the ground. Ideally with landscape fabric in place first. Prevents roots from growing into the earth as easily.

I completely understand about field growing. Hope some of this helps.

Eric:
Great info, thank you for investing the time and feedback. I will heel in my field collected plants on the north side of my house in containers, within a bed, with a windbreak. In winter, the deciduous will come into the garage. The hardy conifers could probably stay outside provided the wind break is sufficient, right? Or would you bring them in from a Colorado winter too?

For the first time I noticed another bonsai professional I know who planted a collected tree in what appears to be 100% sawdust as well. I’m excited to try this method (as I sit here and watch a 10 year old scots pine dying and brittle from a poor collection from the field).

Randy:
Hardy conifers should be ok outside with wind protection.
Larry Jackal puts his trees in holes in the ground over winter.

Eric:
Thanks again. I’m REALLY looking forward to your next Mirai stream. I hope to buy some trees off of you when I get up your way and start studying with Ryan.

Randy:
You’re welcome.

[ATM]

Thanks for sharing, good luck.

[RAY_9FINGERS]

That was a great stream with Randy. Even though I’m in a very different part of the world I think I got more than a few nuggets. The saw dust/wood chip thing is very interesting.

[mw-bonsai]

@PutItInTheGround – Do you think the sawdust healing method will work well on junipers? I saw the livestream with Randy and the photos of his sawdust beds all show pines, whereas when they show junipers on that stream, they are in the pumice containers.

I’ve put a couple junipers into sawdust, but I am noticing that even watering only once a day in Colorado, the sawdust seems to stay moist underneath the top layer, and I’m wondering if that is too wet for junipers, or how to properly calibrate the watering for these collected trees.

Thank you!

[MtBakerBonsai]

Bonsai Floral Gardens in British Columbia puts their junipers in sawdust beds.
I believe this method should work on a wide variety of species, if not all of them.

[darren]

Thanks for sharing.

Have you seen Harry Harringtons method of aftercare for old collected hawthorns? Among other things, he uses a black plastic bag to maintain humidity, wonder if it could help protect from winds in your case?

[mw-bonsai]

Thanks, appreciate that bit of knowledge!!!

[strafe]

I have a question. Randy said to put fieldgrown decidious trees in a sawdust bed for one year after collection. Why?
Fieldgrown would have had a more favorable environment to grow in right? The roots would also have been worked on prior to collecting.

And what’s the difference between fieldgrown and urban yamadori? Part from beeing purposefully planted in growbags, on tiles, root-pruned etc.

Its the ”dont try anything else (but coarse sawdust) especially when collecting from hedgerows…” that’s a bit confusing.

One last thing; can someone explain why coarse sawdust would’nt work in a wood box placed on the ground?
Randy uses coarse sawdust on a weedcloth, rebar’d to a woodframe made from pallets… I dont see the big difference.

[NEBeech]

It works in wood box. I have two 8ftx4ft recovery beds with heatpads , 2-3 inches pumice and 12-14 inches of sawdust. I occasionally will make a small one off box or even do sawdust/pumice in a growbag if I need max root production.

hedge-growers are going to be planting in heavy clay, removing the clay and saving any root is nearly impossible especially fine roots.

The difference is the soil the material is coming out of urban yamadori is much more liklely to have fine feeder roots up around the surface where large hedgegrowers are putting it in deep clay to reduce the amount of watering.

I think the line of thought is: Hedgegrowers= Bagged & Burlaped/B&B= Heavy clay

I would’nt think about it as urban yamadori, hedgegrowers, field-grown ect… What is the soil it is coming out of will give you a much better idea of what any why to do what with what.

As for why the sawdust/woodchips, I have a hypothesis from observation of using this method for 2 years. With the saw dust for a year or 2 you get all the benefits of the oxygen exchange (max root growth) you see with pumice but I noticed some sort of mycorrhizal fungi “like” relationship establish very quickly in the woodchips it is noticeable with all species in the recovery beds. I dont think it is from the sawdust/woodchips but perhaps the nutrient holding capacity or something about the environment encourages this relationship. As we have learned you cant inoculate soil with this relationship it is established when the tree is sapling but perhaps this condition encourages the reestablishment of the relationship? After about 2 years the sawdust/woodchips start to compress and degrade reducing the amount of oxygen so this is an important think to consider and why I assume he gives those timelines. One could speculate the smaller the container the faster this process. Keeping the box on the ground would be a huge plus, Randy does this at scale so it just makes more sense for him to lay out a large section of weedfabric and reduce the box building+added material cost.

For full transparency I actually use 1/2-1/2inch perilite where I stated pumice because of where I live its not affordable for me to get the amount of pumice I would ideally like to use. I find the 1:1 ration Perlite 1/4 with wood chip bedding to be the best results when going in a grow bag or box for recovery, other than 100% pumice.

[strafe]

Thank you very much for taking the time to respond. Great inputs aswell! I can confirm the fungal relationship in the sawdust. Things I planted in sawdust last fall are filled with it.

Got a taste of that clay-soil you mentioned today, digging up a black-thorn on our property. HEAVY and not a lot of fine feeders… Will be placing that in sawdust.
Dug up a lilac yesterday closer to the house and what a joy! Lots and lots of fine roots and great nebari. It came up with a whole colony of ants. I removed most of them but noticed some wandering confusely around the trunk this morning. Hope they’re not gonna case issues…

[NEBeech]

No worries.

Lilac is challenging you have to stay on top of the suckers. I have one I dug off my property, mine is a terrible bonsai tree but I enjoy messing around with it.

The one thing I didn’t mention is with Randy and the landscape fabric. I can imagine that a good amount (enough to bigger a bad situation)of the roots are able to find their way into the ground. They won’t get big corse and structural but they might be enough to take up nutrients or water in a tough situation. Every tree I have that comes back out of my yard post grow bag has so much root mass that escaped and these are thick high grade grow bags. The roots want the earth and will find it!

[strafe]

I’ll keep an eye on the suckers.
About those escape-roots;
I was lucky to get a hold of a couple of cubic sq yards of pumice and built a heatbed out of some of it. Collected and planted some Scots Pine in that in october. Today, about five months later, most of them have crazy roots running out of the bottom. Happy happy spring-time

[NEBeech]

Here are some pics to go with the wall of text. I was doing this tree and figured it was close enough to the discussion to possibly be useful.

It shows the wood chip which I always get nervous someone is going to use carpentry saw dust fines. Typically I would have just done the 1 inch perilite as the drainage layer and then wood chips. But I am trying to get some specific root growth and the tree still needs more development growth before a bonsai pot. So placed some tiles with gaps on the edges and will add a 70% aggregate 30% organic mix. But anyways hopefully the pictures help.

[NEBeech]

I was posting these pics for a bench update but thought I would share the heat/recovery beds I was driving above

[Mike.28]

I would be interested to know what size wood chip is used, I figure the smallest pieces look to be 6mm or above probably maxing out at around 25mm does this sound about right?

[strafe]

I use really coarse stuff. Between 5-35mm.

[strafe]

Nice. I was wondering, I have a big Ash I planted in sawdust this fall and its got a lot of roots coming out of the bottom. Thinking maybe I should repot in pure pumice now or wait til next fall?

[NEBeech]

Here are some closer up pics of the saw dust, it’s bigger than you think but it’s not as thick as pine bark! It’s hamster bedding
1000004011|690x388

[Mike.28]

Thanks for getting back on this one, I have always used pumice for my collected trees but I have an Oak that seems to be struggling so figured the sawdust might be a good option. Now I just have to find the right supplier which seems difficult in the UK