Dahlia Bed Prep- Raised Beds

This is a post I probably should have written years ago based on the number of questions I get about how to fill a raised bed. I’m speaking to this topic from the viewpoint of dahlias but it can be used for general gardening purposes as well.

Raised beds are excellent places to grow, especially if you live in the land of clay soils like I do. Years ago when we moved on to our farm, I saw a sloping hillside and instantly knew that raised beds were my answer.

So let’s talk about the benefits of raised beds:
1. Erosion control- this was huge for our farm because everything is on a hill. The only flat land is our front yard. You don’t necessarily have to have permanent sided raised beds for erosion control- this was the route we choose but even mounded rows will work.
2. Drainage- We know dahlias need good drainage. They don’t like sitting in water. You don’t have to go super high on your raised beds either, especially if you have a bit of a slope. With a slope, 6 inches is about the minimum for how much you want to be mounding your dirt or the depth of your raised bed. On flat ground, go 8-10” if you can. Deeper is always nice but not totally necessary. However, sometimes deeper means a higher bed so you are supporting your back more- totally on board with that the older I get!
3. Timing- Raised beds warm up faster allowing you to plant a bit earlier and also allowing you to plant after heavy rains. We got several days/inches of rain recently. The morning after the storms, I checked the raised beds in the field and the moisture level was perfect for planting tubers! I’ve never had to wait after heavy rains to plant because of my raised beds.
4. Labor saving in the long run- Raised beds are more prep work financially and timewise in the beginning but save so much time over the years because you don’t have to re-till and reshape every season. They are also easier to keep up with weeding because you are usually filling with fresh weed free soil. So if you keep on top of it from the beginning, you won’t spend hours weeding.

Have I convinced you yet? Nothing wrong with in ground growing but I gotta’ admit I love a good raised bed!

Deeper Raised Bed (that needs a little repair work!)

So what are we going to put in that raised bed?

I’ve started raised beds 2 ways and they both work great- one is just a little more work.
Method 1: Mow your grass very short— scalp it. Then cover the area with cardboard and construct your raised bed on top of it. The cardboard will kill the grass overtime and break down. This is the method I use in my vegetable garden.
Method 2: Till the area and get all the grass/weeds out and then construct your raised bed on top. This is the method we used in our flower field. (It would have taken a lot of cardboard.)

After you get your grass killed or area tilled, it’s time to fill it up. I start with a layer of branches- not big ones, nothing bigger than 2” in diameter. Trust me on this one— 2 years ago my husband designed an amazing raised bed for our vegetable garden, he built it and then began filling it with branches— and logs! He knew that branches were what I used in the bottom but I didn’t realize he had put logs in there until the dirt was already on top!! So needless to say, it’s still breaking down. I’ve been growing plants from the cucurbit family in that bed because they don’t mind a compost like environment. It will be beautiful soil - one day!

Once your branches are down, I add leaves if the time of year is right. Leaves are an amazing soil additive. If you can get them shredded- even better. If they are shredded, you can add a lot. If they are freshly raked, don’t put so many that they mat up when wet.

It’s finally time for the soil! You want a good quality compost. Now what is that and how do you find it? #1- Ask gardeners in your area. Compost is going to be different regionally. #2- if you have time, buy a small amount and get a soil test done before committing to a large amount. I always recommend getting a soil test done on your base soil regardless but if you can get it done before you buy- even better. Some companies may even be able to provide you with a recent test done on their soil.

You don’t have to use 100% compost. You can mix it with some top soil if you can find good quality top soil. All compost gets very expensive. This is where a lot of the financial investment comes into play with raised beds.

Compost can come delivered in bulk or you can buy it in bags. Bags are usually a bit more money wise but they are also faster because you don’t have to shovel and wheelbarrow the soil across your yard. When we set up our flower field originally, we used bags because of the geographical topography of our farm. We didn’t have a tractor with a bucket at the time, so I figured that moving bags was less labor than having to shovel and push a wheelbarrow several hundred feet to the field (and down a very steep hill). I just bought a pallet worth of bagged compost at a time. I tell you this because some people have a misconception that buying bagged compost is crazy but if I can do a 1/2 acre field this way- it’ll work for your backyard garden!

My husband’s raised bed design that is far superior to mine! I love the rocks on the bottom.

If you have bought in good quality soil, then hopefully your soil is well balanced nutrient wise. If so and you are planting dahlias, then I would add a granular fertilizer - something like a 10-10-10 or something with a touch higher nitrogen than phosphorus and potassium to start.
(For more dahlia fertilization recommendations, go here).

That’s my method for filling up a raised bed— What’s yours? I always love to hear new tips and tricks!