Hello my name is Logan and I live in northern California in redding zone 9. I have an unhealthy addiction to Japanese maples but am currently only able to grow them in containers. Where I live it gets very hot and I believe I over water my trees in their containers which only consist of potting soil so I was looking for some soil advice on making my own soil to drain more freely. If anyone that grows theses trees in containers in hot summers has any tips I'm all ears.
60%pine bark mulch, 20%perlite, 20%peat. Very simple process, mix all together and repot your trees. My maples drain really good. Good luck keep them hot maples shady. Pat
In Kansas - very hot and often humid in summer, along with frequent wind - my 'recipe' is as follows: Equal parts good quality potting soil (I love Fox Farm's Coco Loco), pine bark mulch (not the nuggets, for bulk/drainage), turface or other similar grit (haydite, dry stall - NOT stall dry, which is a wood fibre product - pumice or perlite), and Hapi Gro (composted pine bark or other similar soil conditioner). With this mix, drainage was good, with it remaining moisture-retentive enough but not too saturated. Depending on your local climate, you may have to play around with the ratios a bit (heavier/more soil; lighter/more bark), but it's a good starting point. Now that we've moved to Alabama, I'm probably going to have to tweak it a bit myself. I also use Fox Farm's Japanese Maple granular fertilizer; not time release, but not instant either, usually takes a month or two to fully dissolve/break down. I fertilize in early spring, around bud-break, then late spring/early summer, before temps get too hot.
Thanks for the tips gang. But I'm having a heck of a time finding pine bark mulch small enough to work. Everything around here that small seems to be fir or redwood would that work? Thanks again for the help
Welcome to the forums Logan. Here a mix of 1/3 Douglas fir bark ( or a hemlock fir mix), 1/3 sand, and 1/3 peat has worked well, keeping the pots cool and shaded in the summer so the roots don't get fried in hot sun, they like their roots cool. It only gets up to about 90-95 deg. F. (30-35 deg. C) here.
Finding the best mix for you and your watering needs will take a little experimentation. I think generally the hotter it is the more soil (water retention) you want. I currently use about 60% partially composted pine bark, with pouzolane and perlite, then some coir and maybe 5% well rotted seaweed compost. But I was only able to get hold of the pine bark in quantity recently, so I had to work with more coir and perlite, and small calibre bark chunks before. I also use osmocote as a fertilizer, because the mix is essentially nutrient-free. Because in Normandie it's not very hot but very wet, I need to go for maximum drainage. Even sand can be problematic. Very good advice to keep roots shaded, I use black plastic pots to grow plants up, and even in our weak sun they can get very hot. The plants are much happier when at least the roots are shaded. Welcome to the forum! We all suffer similarly here (re: unhealthy addiction)... ;)
Good point about the pots getting hot, you may want to consider using the fabric pots, like I do. I use the Dirt Bag line (I prefer them to the Smart Pot brand); started using them about 5 years ago and haven't looked back. I tried changing out just a few maples initially, but ended up switching everything over, including the majority of my potted conifers as well because the plants seemed to do so much better. The only ones not in the fabric pots are the really big trees (ie, 7g and up) and the really small ones (ie, under 1g). Because the pot is fabric, it doesn't heat up in the sun the way the plastic, or even the resin, pots do, the roots can breathe better too. The only drawbacks, imo, to the fabric pots are that you need to account for the soil drying out faster than it would in a plastic pot - easily remedied by altering your soil mix with more organic/water retention - and being more susceptible to the cold in winter - likely not much of a concern for you. Otherwise, they are a winner, and the pots I prefer to use these days.
The pine bark you're looking for might be called something else. My nursery calls it "soil conditioner". Do you have any yard at all? Last summer I kept many of my potted trees actually buried in the ground, much like I do every winter, to keep the roots cooled. They seemed to be much happier. Kevin in KC
Not a bad idea but a lot if my shade is covering concrete but I do have a spot or two that may work thanks for the tip.
