You do not mention any problem with the tree's growth. The figures you have given do not surprise me, what do you find wrong with them? Al

LOTS of water drains out of the gritty mix when you water, especially if the ingredients are larger than ideal. When you fertigate, add the solution only until the pot starts to drain. When you water, use a water break and water the soil until you see water is draining from the drain holes and stop immediately at that point. Your flow through volume will be much less but still enough that you'll be flushing the soil.

FWIW, if you're using a fertilizer with an appropriate ratio (like FP 9-3-6), flushing the soil regularly isn't nearly as important as it would be when using fertilizers badly skewed in comparison to what plants actually USE. 10-52-10 or 5-15-5, even 20-20-20 are fertilizers with ratios that can quickly get out of bounds when you're not flushing the soil.

When using FP 9-3-6, you can water until water just starts to trickle out the drain holes and flush the soil every 2-3 weeks. When you supply nutrients in the ratio at which plants use them, it takes much longer for ratios in the soil solution to become seriously skewed.

Al

Thank you Al, I've learned from you again.
Christine

Your tree looks healthy to me. I don't grow maples, but I do grow large plumeria trees in containers of about the size you are using with gritty mix. In the winter indoors, they are very heavy so I am careful to water only until a small amount comes out the drainage holes. The pots are sitting in saucers with pebbles in them and I don't want them sitting in water. I have found I can slowly add about one quart of water before water comes out the drainage holes. If I add a half gallon (or two quarts) about 50 percent will come out the drainage holes just as it does for you. My plumerias will wilt if they aren't getting enough water, so I know they are doing fine with just one quart at a time. I think your experience is normal.

For those who are new to gritty mix, I have to add that you will need to saturate the mix very well before planting and water more copiously in the first few weeks. It seems to take a while for all the ingredients to be fully hydrated. But once you get used to the mix, you don't need to water so much.

WOW! Sounds as if I've been overdoing everything!
So... I should slowly add my usual fertilizing solution (water and Foliage Pro 9-3-6) , stopping when the solution begins to come out of the drainage holes. Likewise, when mix requires watering only (skewer comes out nearly dry), add water very, very slowly and stop as soon as it begin to come out of the drainage holes. Flush the mix thoroughly with water every 2-3 weeks.
Al, I'm sure you've reiterated these directions countless times in the past. Sorry to put you through it again.
BTW ...

1. Does the fertilizing ratio (3/8 tsp. of FP 9-3-6 per gallon of water) and frequency (three times per week) sound right?
2. Crazy question of the week: If the mix is watered too early (when it was still wet with the fertilizer solution), would this "wash away" or somehow displace the fertilizing solution? (Like I said, crazy...)

Generally I do as Al suggests in his various threads, although I might be a big "heavier handed". I use plain well water and saturate the container about once a week to flush out any fertilizer salts in the soil and make sure the soil is completely moistened. When the water freely emerges from the drainage holes I stop watering. Then, I allow the container sit for about 30 to 60 minutes to drain, then irrigate it again with the water/MG fertilizer solution. When the fertilizer water exits the drain holes I stop watering.

If the weather is cool or if we've had rain during the week, I may not water again all week. I check the soil with my fingers and do not water again until the soil seems nearly dry to the touch.

Hope that helps.

TYG

Nice to hear from you, yard guy. Yeah, I may be overdoing it with the watering but I don't want to take the chance of the mix drying out. And as little water retention as I have, that's always a concern

In my earlier post I meant to say that I'm "a bit heavy handed" when it comes to watering. The great thing about the 5-1-1 and grit mix is that it's difficult to overwater them. Unlike many of those peat-based mixes, which break down and turn to muck at the bottom and turn hydrophobic at the surface, the grit and 5-1-1 variants are much more forgiving when it comes to watering.

We just had a very wet week with several big storms and pounding rain. I checked my containers today and tipped them on edge to check for perched water, and very few, if any, held any excess water.

If you are concerned with your mix potentially drying out you can always add a bit more Turface or DE to your mixes and cut back slightly on the granite. That's the great thing about these mixes, you can adjust them to fit your local weather and growing conditions.

TYG

That's the beauty of mediums made with larger particles... more aerated, sharper draining mediums... the margin of error for over watering is so much larger. This type of medium is very forgiving... it almost can't be over watered.

Under watering is another story, however. If the medium dries out too much, it can become hydrophobic... but this is true of any medium... and it can be corrected fairly easily. If the medium is drying out fast, it gives us a better idea of how often and how thoroughly we need to water.

The most commonly made mistake in container gardening is over watering, though... and this is exactly the kind of medium that saves us from early loss of our plants due to too much moisture, or moisture getting hung up within the pot and creating perched water tables.

The Gritty Mix is perfect for my plant of choice, the Hippeastrum bulb, which will rot in an environment that's kept too moist on a continual basis.

Thanks yard guy and jodik.
I remember being extra careful ... back when I made my first batch of gritty mix ... to precisely screen the ingredients so all would be in that 1/4"-1/8" range. Ended up with a lot of unusable Turface ... particles were too small to be included. Afterwards I read that these smaller particles could, in fact, be used without fear of increasing water retention too much. Live and learn!
Next time, I'll definitely increase the water retention. As you suggested, yard guy, I could increase the proportion of Turface in the mix ... or maybe screen the Turface so that more of the smaller particles are used.

terratoma:

Yes sometimes many of us (including myself) get hung up on following a specific soil recipe exactly. Often times it's necessary, and beneficial, to use the basic 5-1-1 or gritty mix as a generic "starting point". Once you get the feel for the different ingredients and how they work then you can experiment with different recipes, ingredients, and ratios for different plants and different weather conditions.

TYG