I thought I was doing things right, but apparently not since I have been getting a LOT of drying/browning leaves, falling leaves, etc (see attached pictures; this is indicative of many of my maples, though some are doing very well), so I am wondering if I'm not watering enough. Other than the leaves, and a spider mite infestationg that is currently being treated, all the trees appear decently healthy, with new buds forming where leaves have fallen off. I have subscribed to the typical bonsai method of watering potted plants: Stick your finger into the soil, and if it's dry about an inch down, water it. If it's still damp, don't. Therefore, I thought this would work well for my maples (all are in pots currently), and have been watering every 2-4 days, depending on weather, which has been quite hot lately, typically mid 80's or warmer, with low 70's overnight. I know maples don't like wet feet, and I think my mix is a decent one, with good drainage: Organic to inorganic is about a 2:1 ratio, with equal parts pine bark mulch and Fox Farm's Ocean Forest soil for my organic, and equal parts haydite and chicken grit (now replaced by turface, since I can finally get it locally) for my inorganic. I don't want to overwater them and place them under undue stress, but not watering enough is stressful as well. Can anyone offer some tips or advice as to how often I should be watering without drowning them? Should I change my soil mix (not now obviously, but maybe come fall?) to something freer draining?
You are probably underwatering, if waiting 2-4 days in 85°F+ weather. My summer climate is cooler than yours but I usually water container maples every 2 days in dry summer weather, increasing that to every day if it is particularly hot. I have never stuck my finger in the soil to determine if the maples in pots need watering. It would be difficult to overwater in hot dry weather if using a decent potting mix with adequate drainage (and your mix sounds decent).
Watering maples is an art form. I agree with maf entirely. If your mix drains well and you see water passing thru as you water, then as it gets hotter you have to water more often. Humidity is important as well as wind because of the evaporative effect. I watch the weather forecast to gauge my watering needs. Your plants are underwatered at 2-4 days @85F. If you have a good draining mix like maf says you are not likely to overwater. Remember maples are shallow fibrous roots. Good luck.
Thank you both for the advice, and the moral boost that - with the mix I have - I will likely not over water my maples. Yes, the water runs through as I'm watering; not instantly, but definitely within 5-10 seconds I'll see it start to come out the bottom of the pots (all of which have several large drainage holes in the bottom, and are on raised platforms/tables). Typically our humidity with temps like that is around 40-70%; not as humid as the southeast, but definitely not dry either. Thank you again :)
In addition to the great advice already given, I like to water my potted maples once a day now that we are nearing our hottest stretch of the summer. I also add an inch of pine bark mulch (1 to 1.5" chips aged pine bark) to help keep the surface roots cool and moist.
