How I Made Galvanized Trough Planters
I like this idea especially for plants like lettuce which you want in full sun in spring, but in shade when it gets hot later.
If you want to paint them, do so before you fill them. Prime with zinc chromate (another poisonous compound) , paint whatever colour you want. You could also pay to have them powder coated.
For castors, look for ones that have zirks for both the wheel bearings and the pivot race. Grease them up until it oozes out the edges. This will give you wheels that will still roll after few years in the weather.
Use washers to spread the load over a larger area of metal where the bolts come through.
There is going to be some serious sideways forces on the caster mounting if you roll it and hit a bump. I would use a square frame to support it. Given the weight I expect 1/4″ bolts to be too small. 5/16 or 3/8.
Quarter inch is WAY too small for drainage, although with your stryrofoam system it may work. I make pots out of barrels. A barrel half gets 25 1″ holes. It’s then lined with scrap carpet fuzzy side down to keep the dirt in.
If the bottom is styrofoam, there’s not a lot of point in having planters that are that deep. Consider a shallower cheaper container.
In general I’ve not found zinc to rust. It will react to acid, and it will decompose from electrolytic reactions. A zinc bolt on a zinc tank should be good for decades. However every hole you drill should be painted. The hole goes through the zinc plating. Corrosion will spread from here under the zinc.
Check the origin of the troughs. If they are from China the galvanizing may be done with a mix of zinc and cadmium. Zinc and cadmium are often found in the same ore with Cd being a few percent of Zn. Early galvanizing would use the unseparated mix. Zn is poisonous in quantity. I’ve gotten mildly sick from drinking generic Tang from zinc galvanized buckets where the drink sat overnight. (On canoe trips we cooked in buckets.) It’s also a required nutrient in the micrograms per day class. Cadmium is more poisonous than lead.
Your high school chemistry teacher has the stuff for detecting the presence of Cd. You could use the turnings from your hole drilling to check.
Lead is not very mobile in the soil. In Vancouver in Gastown, they found that 2-3 feet next to the houses (where lead from the scrape and repaint fell) was very high, but once you got 10 feet from the house it was normal.
Testing for lead is fairly easy. Learn how to do it, and do spot tests over your yard. You may also find that the lead is in a thin layer. Take off 2 inches, and remove the lead. Build a hill with the spoil and plant decorative stuff on it.
You will likely find that garden beds will have the lead mixed through it, but that grassed areas will have lead only in the top layer.
How I Made Galvanized Trough Planters: Want to make cool galvanized trough planters? So did I! Here’s how I did it.Why water troughs?Lots of reasons.We live in an old house, and old houses tend to have lead in the soil. The nice folks at UMass tested our soil and confirmed it does, in…