One of the biggest obstacles to creating a raised bed garden for many people is the time and difficulty involved in building the raised beds.
I have built many wooden raised beds myself and I can tell you that if you want your raised beds to be fairly tall and attractive and built-to-last, it is not a quick and simple project.
The container must be properly cross-braced so that the significant pressure of the soil and water inside it does not bulge the sides outward (or cause outright failure of the container).
There are some quality raised bed products and kits in the marketplace that can make the process of building a wooden raised bed much easier and tool-free than the pure DIY route, but most of these products are pretty pricey and will require at least some of your time and labor (the shipping isn’t cheap either).
One very good alternative to building a raised bed yourself or buying a kit is a galvanized livestock watering trough (or tank), like the ones shown above.
Qualities To Look For In A Great Raised Bed Container
I must admit that I have no experience using these large troughs myself, but I think that they have several great qualities that a gardener should look for in a raised bed:
- extremely durable and long lasting – even rot-resistant (and pricey) wood like cedar is only expected to last 10 years or so as a raised bed
- depending on your tastes, very attractive and neat-looking
- absolutely no construction necessary other than drilling drainage holes in the bottom
- easy to move around and arrange as desired (when not filled with soil!)
- come in different sizes and can be fairly tall (up to 2 feet high)
- fairly inexpensive compared to most other options, especially if you consider your time and labor (and you might find good used troughs much cheaper than new!)
There is a potential problem with using a galvanized trough as a raised bed for growing vegetables or other edibles, and that involves the safety of the food grown inside of them.
I have scoured the internet for information regarding the safety of eating food grown in galvanized containers, and I can report with absolute certainty that there are varying opinions on this issue.
I think one thing is safe to say – food grown inside of these containers would fail “organic” standards.
Without going into too much detail, galvanized containers have a zinc coating (which can contain cadmium). The coating protects the underlying metal (steel or iron). Over time, the coating corrodes and the zinc and cadmium are released.
Zinc and cadmium are dangerous to humans if consumed in high enough amounts (however, small amounts of zinc are considered an essential micronutrient for both plants and humans).
Here are a few points to consider regarding the safety of growing edibles inside galvanized containers:
- the biggest danger cited with respect to galvanized materials in contact with food is to not cook or serve food or drink inside a galvanized container (because of the possibility that the acidity of the food or drink will dissolve the zinc, thus leaching it into the food or drink)
- another big danger cited with respect to galvanized metal is that it is dangerous to breathe the fumes created when heating the metal (such as during welding)
- humans in rural areas have collected rainwater (for drinking water) off of galvanized roofing for many years
- residential water was supplied in galvanized pipes (and still is in some areas) for many years
- livestock and pets have used galvanized containers to drink water out of for many years
- if the plants in your galvanized container absorb the zinc and cadmium, it will most likely be in very small amounts and the plants themselves will show toxicity if the amounts are too large
- a plastic liner could be used inside the galvanized container to minimize soil contact
- older galvanized containers that are rusting would be much more dangerous than newer ones
My advice would be to simply use your own judgement regarding growing food inside a galvanized container. I can see both sides of this issue, but would probably lean towards not being too worried about it myself.
Of course if your goal is to grow flowers or other non-edibles, there is no issue whatsoever.
Getting Them Ready To Plant
If you decide to try these troughs, it is important to make sure that you drill enough holes in the bottom to provide adequate drainage.
It might be a good idea to use gravel or some other material in the bottom to aid the drainage, just as you would in any container. A mesh liner of some kind under (and/or over) the gravel would help to keep the soil mixture from draining out over time.
A final consideration regarding these troughs is the fact that in a hot and sunny environment, the sides of the trough will get very hot and transmit that heat directly into the soil. You may want to place the troughs in a location that is at least partially shaded, especially in the afternoon.
Also, if you are trying to extend your growing seasons, these containers would not be ideal because they would lose heat quickly at night through their metal sides.
The ideal material for a raised bed container for this purpose of extending your growing season would be something that collected and retained heat (slowly releasing it into the bed at night), like stone or brick.