There has been a lot of hype lately about growing plants and vegetables in raised gardens. Are they the right thing for you? Here’s why I say you should avoid raised gardens if you can.
I understand there are benefits of raised gardens and for some of you, it’s just the thing. You can have high raised gardens that save your back (no more bending over IS nice, after all). Or, you’re in an urban area and you don’t have a garden; in that case, you can put a raised garden anywhere, even on concrete.
Agreed, some raised gardens look great. I have seen some great raised garden designs. And if you’re renting, you might not be allowed to dig up the garden. A raised garden is great in this situation.
But… If you have land and space, grow in the soil instead.
The Disadvantages of Raised Gardens
1. Raised Gardens Are Expensive
Raised gardens can get expensive. Not only the building materials but also the soil and compost to fill it. You can’t use any old soil dug up from somewhere, soil in a raised garden needs to be of exceptional quality. There’s no room for error; I’ll explain more about this below.
Don’t discount the labor cost either. Most of us will build it from scratch or buy a kit. But, it can take a lot of time of effort, not to mention the back-breaking work of filling the thing! Many a wheelbarrow goes into a raised garden.
2. You Need Exceptional Soil
The soil in a raised garden needs to be exceptional. The soil is everything. There is no Mother Earth giving you a helping hand, as there is in a “normal” garden.
In an in-ground garden, you have a whole ecosystem you can feed and nourish. You can encourage worm and microbe activity. Your garden is an eco-system on its own and nutrients share around.
The soil in a raised garden gets tired much easier than the soil in your garden. You’d never think of replacing the soil in your in-ground garden (not usually anyway). But, you may well find yourself replacing the soil in your raised garden.
We replace the soil in raised gardens yearly. After a year, it lacks vitality and nutrients and doesn’t grow nice vegetables anymore. If you are on top of adding nutrients, your raised garden soil might last longer. I have no doubt you’ll replace it at some stage, though.
3. Raised Gardens Get Dry
Raised gardens get dry! This depends a little on the area you’re in. For example, in a cold area, this will be less the case than in the hot tropics.
I have seen a lot of tips to “not overwater” raised gardens. There’s no such thing. When the soil in your raised garden is good, drainage will be no problem. It’s incredibly hard to overwater.
I have a raised garden next to the carport and it needs watering every second day when it’s not the wet season. It has a deep layer of mulch and the raised garden itself is deep, but it still needs watering all the time.
It’s hard to keep the water in the soil without it running off. Raised gardens create “tunnels”. Tunnels are spaces where water frequently runs off. Water always finds the easiest way down, so it keeps going down these tunnels. Water goes through the tunnels but doesn’t get anywhere else in the raised garden.
Unlike plants in pots, you can’t plonk a raised garden in a bucket of water to re-hydrate it. When your raised garden gets dehydrated, it’s hard to re-hydrating the soil. You’d have to resort to wetting agents and the like. A thick layer of mulch will help prevent this, but it’s unavoidable to some extent.
Knowing when to water is also harder. It’s not rocket science in the garden. Stick your finger in and you can feel whether it’s moist or not. In a raised garden, just because it’s moist doesn’t mean it’s wet enough.
4. Wood Robs Nitrogen
If your raised garden is wood, at some stage, the wood will start to decompose. As it decomposes, it robs all the nitrogen from your soil and acidifies it.
You can fix this by adding nitrogen and raising the pH of your soil, but it is extra work. You’ll also need pH tests and soil nutrient tests to check the levels before adding anything.
5. Rot or Rust
Depending on the material you use, it will degrade. Having wet, or at least moist, soil sitting in it 24/7 does a lot of damage to most materials. Anything metal will rust, with the added headache of potential iron overdose (and other elements) in your soil. Wood rots.
Wood attracts termites. A real nightmare if you’ve got wooden structures on your land, especially your house! We had a huge termite infestation in our last house, an old train carriage. They destroyed at least 60% of the house before we stopped them. They ate all the window frames (inside the paint, so you can see it), the door frames, and anything that wasn’t proper hardwood.
Rusting metal raised gardens are also sharp, causing a nasty cut.
So, no, I don’t think you should start a raised garden if you don’t have to. The disadvantages far outweigh the benefits. The few raised gardens I have don’t perform anywhere near as well as a nicely-prepared in-ground garden.
But, if you have decided you want a raised garden, here are some tips to make it work.
Tips for Successful Raised Gardens
Start small. Start with a small raised garden to see if it works for you.
Keep any weeds down with a deep layer of mulch.
Start with easy seedlings like lettuce, parsley, and basil
Make sure you use great soil. Good soil is important in any garden, but it is essential in a raised garden. There’s not a lot of room for error here, so get the best soil you can afford.
Make it as deep as you can. Shallow raised gardens are much harder to deal with than deep ones.
Add trellises to grow vegetables up and save space. One zucchini left to its own will take up a huge amount of space, for example. Train it up so you can grow low-growing vegetables in front. Here are 15 sturdy trellis ideas.
Fertilize regularly. Use a good organic fertilizer, as often as the packaging says.
Start a compost pile so you have a ready supply of goodness to add to your raised garden. Remember, raised gardens do not “make” their own nutrient like an in-ground garden might. You’ll have to feed it everything it needs.
Plan for a cover. Raised gardens are even more susceptible to bugs and animals than in-ground gardens. It’s a good idea to plan for an animal-proof cover if the need arises. Could be anything from a simple net cover to a complete roof.
This is especially important at the moment, with the Coronavirus causing havoc. Try to grow in-ground if you can. You’ll find that growing vegetables is easier in the ground than a raised garden. Don’t be afraid to put your edibles nice and close together (see why in my Wild Food Forest article) and try growing some “weird” veggies too!