Preventing burned leaves on deciduous trees in the summer involves two things: 1. We need a lot of fine roots. 2. We need to water frequently. Let’s break that down a bit.
If we don’t have a lot of fine roots, it won’t matter how much we water because few roots won’t be able to support the water needs of the tree at 95 F/ 35 C. If we overwater before we have many roots, we won’t get many more to emerge. And if the tree is in a poor soil mix, we won’t get many fine roots for that reason, too.
If we do have a lot of fine roots, and yet don’t water more than once a day at 95 F/ 35 C we will likely get burned leaves on our beeches, maples and other deciduous trees anyway. On a hot sunny day be ready to water 3 times a day. If your lifestyle does not allow that, then set up a watering system for the one or two watering cycles that you can’t do by hand.
Both of those requirements must be met to prevent burned leaves. Take a look at these photos:
This is the soil of the Japanese maple also shown in the next shot. There are many fine roots all the way to the top of the soil surface. They even climbed up and went into the fertilizer pellets on the surface. That kind of fine root growth is what you want to prevent burned leaves. If you don’t have fine roots bumping happily along the top surface of the soil and through your moss you can be sure it has not colonized the pot and it is only growing along the sides of the pot, which is the worst place for them. On the sides they will get scorched by sun hitting the pot, and will suffocate in a pool of water at the bottom—and that is a very unhappy and unstable tree.
Japanese maple, Acer palmatum, at the end of August.
Red maple, Acer rubrum, at the end of August.
Great post (and recent frequency of post). I was thinking my maples were getting too much sun because the soil always seemed wet but the leaves were getting the edges singed. I think this cleared up a lot. Thanks for the Juniper article as well, I was definitely confused about that bit of information as well.
michael
do we get the fine feeder roots to grow above by spreading some sifted spagnum moss ?
Yes! Sphagnum is a great help in getting fine feeder roots to colonize the top layers of soil. And that sphagnum moss is a great nursery for live moss to grow, too.
I think I need to add more pumice to my mix …for my maples…..I’m assuming you use a fair amount in your mixes?
Cheers Graham
Yes, I do use a lot. Depending on the tree, I can use as little as 30% pumice or as much as 70%. For the maples I would say about 50% is a good starting place. If you grow pines you might well wish to use a bit more pumice. But if you’re using akadama as your secondary particle you don’t need to worry about soggy soil, really.