Potting soil : Japanese Maples

[Gary.Indiana]

Hi, all:
I will be receiving an order of grafted Japanese Maples around Aug 1 at my home in Zone 6b/7a.
I will transplant them into one gallon nursery containers, where hopefully they will be happy for a year or two before up-potting.
My soil medium will be home grown leaf compost, perlite and likely some bark nuggets.
I am considering adding to my blend some standard store bought potting soil.
Any thoughts on adding a potting soil, like Miracle Grow, that has fertilizers this late in the year?
My only concern, at this point, is getting the tiny trees to stay alive until Spring.
Thanks,
G

 

[Bonsai Nut]

How/where will you be overwintering them? 1 gallon pots are pretty small - I'd be surprised that a grafted tree came in something smaller than a 1 gallon pot.

 

[Gary.Indiana]

They come in a containers called Anderson pots,
3 5/8”, I believe.
They are smaller than the #1 nursery pots that I use.
In the past, I’ve planted the 1gallons in the ground to help protect the young roots during the winter. I also keep the buried pots under a makeshift cold frame over winter to protect from wind and ice forming on the tiny trunk and branches.

 

[leatherback]

[please adjust your profile to include the location & USDA winterzone so people can mare more accurate assessments of your specific environment]

I would just get organic fertilizer pellets (regular garden stuff) and add a handfull to the pot after potting up and not worry too much about all these store-bought potting substrates as addition if all you are after is fertilizer.

Keep your mind open towards airlayering the cultivar off from the graft and just grow them on their own roots next spring. Now that they are young, they should root pretty quickly.

 

[Gary.Indiana]

To clarify … my concern is inadvertently fertilizing too late in the year. I’m worried an off the shelf potting soil will contain fertilizers that would encourage growth too late in the year. I’m not at all considering adding fertilizing pellets.
Sorry, I suppose my question was not clear.

 

[Wires_Guy_wires]

To clarify … my concern is inadvertently fertilizing too late in the year. I’m worried an off the shelf potting soil will contain fertilizers that would encourage growth too late in the year. I’m not at all considering adding fertilizing pellets.
Sorry, I suppose my question was not clear.

Fertilizer doesn't jumpstart growth, that's a myth. It fuels growth when it's happening, yes.
It's the plants internal system that does dictate when a plant should grow, usually in response to seasons or injury.
Maybe if you start seeing sugar and coconut water as fertilizer, you might get some response from the plant but regular NPK+trace elements does not do that.

 

[Gary.Indiana]

I appreciate that. In my research over the years I have been told that fertilizing late in the season can be harmful, as it promotes growth when the tree should be preparing for dormancy.
Just doing the best I can and trying to avoid mistakes!

 

[August44]

I appreciate that. In my research over the years I have been told that fertilizing late in the season can be harmful, as it promotes growth when the tree should be preparing for dormancy.
Just doing the best I can and trying to avoid mistakes!

I personally don't think you are wrong with the late fertilizer thoughts, but it depends on the type of fertilizer, the plant you are putting it on, and the winter weather where you live. If new growth on a tree gets frozen in the fall before it sets, your probably going to lose it. If you late fertilize Larch with slow-release fertilizer with a good amount of nitrogen, the Larch will store a lot of that and then gobble that up what's left in the spring and then the needles on the larch will be unbelievably long and the tree will be a mess. I've experienced both of these happenings and many others. One has to think about what they are doing and what could happen. If your close to a bonsai club, ask one of the more experienced people there to help you decide things for your area...huge help.

 

[Bonsai Nut]

In the past, I’ve planted the 1gallons in the ground to help protect the young roots during the winter. I also keep the buried pots under a makeshift cold frame over winter to protect from wind and ice forming on the tiny trunk and branches.

OK - 1 gallon is pretty small but if you are protecting them as you describe you should be fine. I would skip the store-bought potting soil. On small Japanese maples I use a mix of 50% pumice and 50% sifted pine bark fines, which in 1 gallon pots is good for one full season of growth, but by then I'll be up-potting to 2 gallon squat pots. It is very important to make sure the pots drain well; don't let the chunky organic matter break down to the point that the tree becomes root-bound.

I personally wouldn't hesitate to keep fertilizing my trees until they drop their leaves in the fall. A Japanese maple will stop growing when it senses the onset of fall weather, regardless of whether it is being fertilized or not. The main thing is to avoid messing with roots or pruning in August. If you prune the tree or prune the roots in August, that WILL trigger new growth, and the tree may not be able to push new growth and then recover prior to winter, particularly in Gary Indiana

 

[Wires_Guy_wires]

I have relatively mild winters that sometimes pop a little heat wave, never in my 25 years of observing plants have I seen them produce growth from fertilization alone. Unless, like Bonsainut and I said, it's in response to damage or temperatures.
It's a very persistent myth.. like the P + K feeding that should increase flowering behavior. I've dug into the science and found that the positive effects of P and K feeding relate to seed mass; the seed mass increases and the yield of a crop can be increased with it. Those studies were done on cereals, mostly, those are wind pollinators too, so they don't even produce actual flowers. An excess of Nitrogen can inhibit flowering, and that information got combined with the PK stuff in cereals.
Somehow that got turned into "P and K force plants to produce more/better flowers" and nutrient companies went haywire with it, I don't blame them! It's their income and they only have to sell 2/3rds of their normal product for double the price.

There are materials that increase flowers, flowering size, and can jumpstart growth, but those are classified as plant growth regulators, because they're complex molecules with maybe two or three atoms of Nitrogen in a carbon-hydrogen skeleton.

One thing to watch out for in winter storage and also in general, is ethylene. Ethylene gas can be a jumpstarter for growth (among other things) and it can be released from PolyEthylene (PE) plastics that are often used in wrapping. A little bit does no harm, but storing a huge roll of it - you would be able to smell it from a distance, that typical plasticky smell - could potentially do have effects.
Ethylene gas is why one degrading piece of fruit can ruin the whole bowl.