I got your email, Louise - Sorry, I've been away at a bonsai show & visiting friends/family. This is a tough one. As I understand it, you have a concrete block planter constructed atop a concrete slab, with no way for the water to make its way into the sand below the slab. Drilling holes in the block walls won't improve drainage. The only 2 ways to effectively improve drainage would be to make sure there is a 'bridge' between the soil in the planter and the sand below the concrete so the water can percolate through the soil, or to make sure the soil you use is porous enough that it holds little or no perched water. This would mean that your soil particles would have to be large & stable, insofar as their structure is concerned. Even the soil you see me holding above would be inappropriate for your application because that soil depends on the wicking action of the earth (in RBs) to ensure it doesn't remain saturated after rain/watering. It looks great, but if you have high standards it would be a disaster in a container or in your app. I'm thinking that about an 80% fraction of a mix of all purpose sand and all purpose gravel and 10% each of pine bark fines and Michigan (reed/sedge) peat or good compost would probably be the direction I would head. In subsequent years, I think all you'll need to do is mulch with pine bark to keep the soil healthy. If expense isn't a major consideration, you could use Turface MVP as the base ingredient for your soil. Topsoil and fine sand just isn't going to drain w/o help. The alternative would be to remove the old soil and cut a hole in the slab so water can drain from the soil in the planter, but it would have to be a hole of considerable size - preferably at the lowest point on the planter's bottom. If you have pictures, it's possible that something else might be devised that will allow the water to move out of the soil via some sort of passive wicking mechanism that we/you could devise, but I'd have to see the application in order to envision the possibilities. There might be a way to employ a false bottom by placing FRP panel on top of cement blocks that are resting on the bottom & building it like a self-watering container in reverse - where you employ a wicking column of soil to REMOVE water instead of supplying it, but I don't know how far you want to chase the issue? ;-) AL

Let me start by telling you that you have a beautiful garden! I brought in the expert to look at your question and offer an opinion, the hubby is a bricklayer and has plenty of experience with retaining walls. You, unfortunately, have way too much soil that needs to be held back to prevent the wash out that will occur without a full retaining wall. The terraces would erode rather quickly if you just had retaining blocks stacked loosely. Their strength is in having them stacked tightly with the gravel interlocking them. Sorry to disappoint. Good Luck, Tracy & Ed

I just did a shower very much like yours with Kerdi for a local prep school here a few weeks ago. There's no need to fir out the walls at all. Just kerdi right over the block. I'm showing this last pic only because it shows the Kerdi drain. I wanted to take progress pics of this as I went, because I KNEW this would come up, but I forgot to, so there's my proof it's a Kerdi shower!! :-)

Hello everyone, I love these glass blocks I seen these last year a craft show. they are great gifts. this past weekend I went to a craft show and saw something different with the glass blocks they are making them as a fish bowl for those beta fish, with a bit of gravel and a plant. in the top they cut a oblong opening, and were selling them for $25. Just thought I would pass this along for those of you working with the glass blocks. shelly