Can soil be too well draining?

Subject line pretty much says it all.
I re-potted my Black olive this pass weekend in a gritty (1 part granny grit, 1 part turface and 1 part pine bark fines) mix. It seems to drain too well and I'm concerned I may need to water more then twice a day, which I can't. Five days a week.

Thanks for looking,
Joe

Can it be too well-draining? I suppose. If your soil has no water-holding capacity at all, the water will run through and the tree will suck it dry very quickly. Especially if the grain size is fairly large you will quickly reduce the water holding capacity. This, combined with the material properties (Porous or solid?) of the substrate will determine how quickly your soil dries out. What 'grainy' component did you use? I have seen people use rounded pebles, which I think would dry out too quickly.
I have found that watering twice in a row (Gowing through all plants and starting from the beginning) will help to really saturate the substrate, staying moist longer on hot days.

You can lay damp sphagnum or a damp towel over the soil to cut down on evaporative loss. My location isn't nearly as hot as where you are, but I think this ought to get you through the day.

I grow everything in straight Turface MVP and only need to water once a day for the whole season (except for trees/groups in very shallow trays that need 2 waterings on a very the few hot days here).

LittleJoe wrote:Subject line pretty much says it all.
I re-potted my Black olive this pass weekend in a gritty (1 part granny grit, 1 part turface and 1 part pine bark fines) mix. It seems to drain too well and I'm concerned I may need to water more then twice a day, which I can't. Five days a week.

Thanks for looking,
Joe

I have experienced this problem and have mitigated it by adding a little sand to my mix. Either pool filter sand, play sand or paving sand will work. This will change the water retention capacity dramatically.

Zach

You can still use the same mix, just with smaller particles.
Coarse particles hold less water, but more air, if the drainage is too great use smaller particle size. It does holds less air than a coarse mix.

Thank you all for your replies.

Zach, could I use my waste turface (went through a #10 screen) as a substitute for the sand?

Most likely it would work. Your challenge is to reduce the average particle size of the inorganic part of your mix. I know it goes against traditional wisdom, but I've found a lot of benefit for small bonsai in shallow pots which tend to dry out more quickly than trees in larger bonsai or nursery containers.

Zach

Joe, you might be surprised how much moisture that soil mixture can hold and still just let water drain right through. The particle sizes on the grit and Turface are already on the small side, so the mix will hold more moisture than something like Boon mix. If you're worried about it put some chopped sphagnum moss on the surface of the soil.

Some of my broad leaf trees were wilting in our 30C plus weather recently. I scattered some compost from my vermi bin on top of the elms and maples etc, and it has helped on the really hot days when I might not get a chance to water until late. It also has really helped out a poinsettia that was potted in half "peat" based potting mix and half turface. I broke up the hardened surface soil and mixed in the fresh compost in that one and gave it a bit of shade. It perked up and put on new growth within a week and even some back buds. This thing was abused for years as an office punching bag, I mean plant.
Yes you can have a mix that can drain too quickly if it dries out before you can get a chance to water it.

LittleJoe wrote:Thank you all for your replies.

Zach, could I use my waste turface (went through a #10 screen) as a substitute for the sand?

i'm not zach, but from what i understand, turface has been under fire from some factions and per that discussion,
the fines might have a tendency to become gluey/clumpy (for lack of better terms)...

somebody please correct me if i am wrong...

oh wait...

a soil discussion ???

of course i'm wrong !      

kevin

I have heard those complaints, but a periodic breaking up of the surface can alleviate these issues. It is a good opportunity to weed and straighten out the surface roots. That being said, I have been gradually phasing out turface in favor of akadama and pumice.

i been hearing some of the same gripes about akadama... (no personal experience)

i have been using diatomaceaous earth from napa with good results and no breakdown over a couplafew years...
http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Oil-Absorbent-24-QT-Diatomaceous-Earth-Absorbent/_/R-NFN8822_0189041133

and if your looking for a substrate amendment to retain moisture, aged pine bark is awesome and doesnt break down for a looooong time.
but i would use something bigger than the fines, which might just wash out... larger pieces, might not look as good, but you know they are doing their job... and if you are entering the contest, you can always top-dress the soil.