To Line or Not To Line a raised bed's perimeter?

Question

Novice gardeners here. Already feeling overwhelmed. So, I'm taking over hubby's raised bed. It gave us tomatoes over 3 years ago, since then its been sadly neglected. He lined the inside walls with black plastic and was full of weeds. I've removed the weeds, torn up plastic tarp and all dirt down to bottom soil. The base soil still has lots of little weed roots (they look like crazy wires) which I'll dig out before reincorporating the good soil in.

I decided to lower the bed (bad back!) to about 1 foot by removing some boards. There are gaps between them though. Should I line the inside walls again? These boards are about 5.5" wide. If I don't line I'm afraid my dirt will seep out through the gaps. Any pros for notlining? I also plan on removing about 4 inches of the grass leaning up to the raised bed (highligted with red here). Thanks for your help!

Answer 1

Well, I'm no expert so take this answer with a grain of salt. I've used shallow raised beds but never more than one board high so I've not experienced your issue. That being said, I did some poking around and found this non-commercial thread that you should find interesting. To summarize (in case the thread eventually goes away): You should line the sides when:

• You've used treated lumber to build the beds. In this case, line with heavy-grade plastic to prevent leaching of the preservative chemical(s) into the soil. Note that this could encourage rot if the plastic is not tautly stapled to the wood.
• You have issues with soil runoff. In this case, you could use plastic, although I would use landscape fabric stapled taut to the inside of the boards. Note that this may encourage rot. The thread I linked to has exactly your issue (on the 2nd or 3rd third set of posts).
• You want to enclose the bottom. I don't recommend this because it could hurt drainage, prevent movement of worms into the bed, and restrict long-rooted vegetables like tomatoes (and some root crops, of course).

Here's another site that you might find interesting. Note that I disagree with some of the author's recommendations (like lining the bottom with hardware cloth - this is absolutely difficult to work around when you're working the soil).

I hope this helps - good luck!