Starting a raised bed

dahlia1972 · 2023-03-30T03:45:13+00:00

I've just built a 6x6 ft by 14 inches deep raised bed for my dahlias. What kind of soil and amendments should I be using and how deep should the soil be? I'l...

MissyWeitzel

dahlia1972 @blown_dry has great suggestions here! When I started raised beds in my vegetable garden I did the cardboard thing too and covered that with a mix of approximately 30% compost and 70% screened topsoil. If you go the cardboard route, make sure to peel off any labels or packing tape, as those will stick around and annoy you later. Cardboard is actually pretty awesome not only for killing the grass, but also the glue that is used in the cardboard pressing process attracts a lot of earthworms which do their thing and improve your soil. Now my veg raised beds are only 4" tall, so it wasn't too expensive to fill them with ordered soil and compost. If you have really tall ones, her suggestion of filling the bottom portion with branches is a good one because it's healthy for the soil plus it takes up some of the space. If you want to go a step further, read up on the hugelkultur method! 😊
My husband designed and built my lovely vegetable garden fence and gate with a little help from me. His health isn't so great these days so I'm very thankful and grateful for that gift. Anyway, you can see the raised beds here.

Krista

dahlia1972 This is a great discussion topic, I'm so glad you created this - there's such good advice here! I have raised beds on a small, urban lot and I'm here to share that I crammed all of my winter, organic straw mulch from the previous winter into the bottom of the new 15' raised bed I built last spring. I was hoping to take up space like you, and I can confirm that my soil dropped a dramatic 6" by halfway through the growing season. While this is zero surprise to me now, it was not something that I had anticipated for who-knows-where-my-brain-was reasons. So I'm a plus-one on blown_dry's advice to use not-floofy-stuff like thick branches and small logs! Also, we are intense coffee drinkers and egg eaters and we have a separate bin for composting grounds and shells only. I added a healthy amount of this to the raised bed and the soil was pillowy and delicious for lifting dahlia clumps in November!

dahlia1972

Thanks for all this advice!! How deep should my soil be? The bed itself is 14 in., was hoping I could get away with 10 in of soil. I'll be putting chicken wire at the bottom of the bed and lining it in plastic.

Krista

dahlia1972 I didn't use rat wire because we don't have an issue with tunneling where I am, but I did line my beds with a couple layers of Dewitt Pro-5 Weed Barrier to help keep the overzealous plant *friends out!

calico20hill

I have been happy with 12" of soil in mine . Not sure how it would do with less. I would recommend Rat wire rather then chicken wire. SOme creatures can easily chew through chicken wire. It isn't even strong enough to really protect chickens though it will keep them confined, but wild creatures can chew right through it. Rat Wire, aka "Hardware cloth" is so tightly constructed the little varmints can't get their jaws open to chew. It will last for a long time without rusting out. Ask me how I know these things....no don't....

Juliarugula

Hardware cloth is good stuff. Chicken wire will rust out more quickly than hardware cloth also.

SteveM

Hardware cloth is well worth the extra $$. Also, I wouldn't line the bottom with plastic, it would like;y impede the drainage and with a heavy rain you could end up with a raised swimming pool.

blown_dry

Seconding the not bothering with chicken wire. It will rust and is not strong enough to keep out gnawing critters. Not sure what the plastic will accomplish. It's one thing when it's used for paths and gets hosed off, etc., but as soon as you put soil or mulch on it it's not long before the weeds that colonize on top make the barrier meaningless and it needs to be dug out by someone later after it's got a bunch of dirts and roots on top. "Ask me how I know these things....no don't...." 😂

dahlia1972

I've decided not to use plastic on the bottom- my tubers have done really well in my mom's raised bed and she said it was lined with plastic, but apparently only the sides were lined to protect the wood, so I'll follow suit. I guess I'll scratch the chicken wire idea too. My friend's tubers were destroyed by voles so I'll try hardware cloth to protect them, as a vole rampage would be disastrous.

SteveM

There is also a "gopher wire" made specifically for raised beds which might be worth looking into, especially if it is available locally.. It is similar to chicken wire but smaller mesh and heavier galvanization.It is probably cheaper than hardware cloth. I have never tried it but am considering it.

JessieC

This is an excellent description of how to grow dahlias in a raised bed:
[https://mygardenbee.com/blog/f/growing-dahlias-in-raised-beds?blogcategory=Raised+Beds](https://)
I’ve followed Paula’s advice since I started growing dahlias, which is admittedly only a few years. But I return to it again and again because she’s very clear and she illustrates things well.
I’ve added a couple of raised beds for this season and I was just fiddling with the soil. We reconfigured one large (8’x16’X 6”) bed as well. Last year, I used an existing 10’x10’ bed and the shape just wasn’t ideal for cut flowers. The new bed will allow for long rows with an aisle in the middle for access. My smaller beds are tall like yours. They’re similar to the metal ones in this blog post. We used a bulk garden soil mix from a very good local company that includes compost. I’m amending it with compost and trying out some of the ideas in this post. I’d start with a soil test, of course. In fact, I am waiting on results from a new test that I sent in for this year. Right now, I’m going for the right texture, if that makes sense. Now that I’ve done this for a few seasons in a row, I have a better idea what I want the soil to feel like. The raised bed is great for that because you can experiment. I had very good luck with the tall raised bed I did last year. I used sticks as suggested above, and it drained beautifully. It was also easier to tend than the lower bed. My plants did well and the tubers were so easy to lift! Good luck!

dahlia1972

JessieC Thanks for this information. What soil should are you testing? They won't be coming into contact with my ground soil, and I'll be ordering soil in bulk to be delivered, which I can't test beforehand.

JessieC

dahlia1972 I tested the soil in the raised bed. It's not strictly necessary, but does help you dial in on what you need and what you don't.