This research article focused mostly on hydroponic water using “watering from below”. If you water your houseplants or containers by setting the pot in a saucer and then filling the saucer, it’s the same thing.
Turns out the water only goes up about 80% of the way in the container and the top 20% will remain too dry.
I have done this with my seed starting trays. I water them from the bottom so I don’t disturb the soil or the tender seedlings. But I have noticed I do have to heavily mist the tops to keep them moist.
Now I know why and I’ll go back to watering up top.
(In the nursery, I had misting systems that kept the tops constantly damp so there wasn’t an issue but on the home scale, I learned something this week) 🙂
Bottom line: water from the top of the container.
The original research report is no longer available. Feb/19
Raised bed gardens have their supporters, that’s for sure but they aren’t a cure…
Here’s the deal from my point of view gathered over 30 years in the nursery industry. I’m not going to sugar-coat this article because I know there are a lot of folks who really think raised beds are the greatest thing since sliced bread.
In many ways, raised beds are simply big container gardens.
I think it depends on your gardening style and garden. Here’s my experience with this style of gardening. You can either make raised bed gardens by mounding up soil or by constructing boxes (of almost any material) and then filling the boxes with soil.
These are however essentially two distinct ways of gardening and I’ll explain this below.
Our raised vegetable bed — I built it because we only had 3-inches of soil over shale rock. The overhead supports help hold the sides upright (the weight of the soil bowed them out) and used for growing tomatoes and other vertical gardening crops.
The Advantages of Raised Bed Gardens
The soil warms up faster in the spring. It’s above ground level so the sun gets to work on it from the top and the sides.
They are closer to the gardener. Which is just another way of saying the gardener doesn’t have to bend down as far to reach the plants. 🙂
Superb for differently-enabled gardeners who may not be able to bend or kneel comfortably. Wide rows between the beds enable wheelchair access.
A good raised bed can act as a garden when you don’t have enough soil (like my garden).
Disadvantages of Raised Bed Gardens
Raised bed gardens use more water than soil-level beds.
Large (taller) beds act more like containers than garden beds so you have to modify the soils and watch your fertility if you are going to have truly wonderful gardens.
Can’t be walked on or if too high, over top of (you have to walk around them and this gives me more grief than any other characteristic of them — from a practical point of view in my large garden.)
You can’t use machinery such as rototillers to till or modify soil — it’s all hand-work. On small beds, this isn’t an issue but when I tried to make permanent large beds in the old farm vegetable garden (a very large one) then it quickly became apparent that I wasn’t going to do a lot of digging.
Mulch is tricky to keep on top of raised beds. It seems to migrate to the sides of the beds.
Expensive. I have to raise my garden beds because I have very little soil and this means the costs of 6×6 beams and the extra costs of fill and topsoil to fill up these beds.
In-ground raised beds (where you use a hoe or rake to create raised beds in a regular soil garden) are more work every year and this extra work isn’t worth it if you mulch heavily for weed control (heavy mulching will slow down the heating and reduce the main reason for using these raised beds.
Perennials and woody plants might have trouble overwintering depending on the nature of climate and the size of the raised bed (bigger beds make it easier for plants to survive).
You’ll still get weeds and they’ll grow in the rows as well so your weeding isn’t reduced.
Should you use raised bed gardening techniques? It depends. I use them because I don’t have much soil where I want to garden and my raised beds help me create the necessary depth. Are you prepared to use the increased amount of water they require? Any time you raise soil above the ground level, gravity will suck water downwards to the normal below-soil-level mark. Do you want extra early crops of vegetables?Raised bed gardening is one answer for you and combined with other early cropping techniques can really make your vegetable garden come alive earlier in the spring. Do you have physical challenges?Then custom building raised beds may be the answer. Are you concerned about the high heat of summer? Then raised beds might not be the answer as the soil temperatures can get too hot for good growth of some plants. For example — high heat will make vegetables such as lettuce quite bitter.
Raised beds will be useful for some folks for the reasons above. But they’re not a panacea. They don’t provide any form of garden advantage other than a physical one and/or an early crop.