I just put together a 10x4 raised bed garden using cedar boards stacked 2 high.
I am a little concerned that the small gap between the stacked boards will let water seep out.
Could you provide any recommendations for sealing this gap? It would have to be soil/food safe.
My initial thought was to use 100% silicone caulk along the inside of the gap. Do you think this is a good choice or are there better options?
It was completely unnecessary to seal the cracks in the raised bed. I did however line the inside of the wood with landscape fabric.
Update: After a year, I recommend NOT sealing the gaps between boards in a raised bed garden. You actually want water to leak from these during heavy rains so that it does not flood your raised beds.
I'm in the Phoenix area and have had two raised redwood boxes for three years, unsealed and placed directly on top of cardboard and heavily compacted clay soil.
Due to soil problems, I decided to empty the boxes out a few weeks ago and try again. I'm glad I did as one box was filled with the neighbor's Tipuana tree roots. I was also able to see how poorly the redwood was holding up; in addition, they showed pretty significant termite damage. I assume the degradation was due to constant moisture (in no way "mud" though).
My husband laid a sand base and then mortared in cheap 12" pavers from HD around the outside edges to help contain the pavers in place. Per my request, he left a little ¾" gap between a row of pavers to help with any drainage issues. I will lay a strip of hardware cloth across that gap (to be safe in case any roots wind their way up). I have also brushed/cleaned the boxes using a brush attachment on a cordless drill and a putty knife to help clean out as much debris as possible from the cracks.
The boxes have aired out for two weeks and tomorrow I will seal them using an "eco-friendly, non-toxic" product called Garden-Seal. I'll also line it with landscape fabric. HD redwood boards are not necessarily cut very straight, and these both have about ¼"+ gap on two sides between stacked boards. I'm hoping this will give a few more years of use to these boxes without invading tree roots.
Wanted to share as everything I read prior to building said Redwood is supreme and should last at least five years, if not 7-10 years. This has been a laborious and time-consuming process and I will take these steps for future builds.
Depending on the drainage of the soil content that your bed is laying on and if it's open on the bottom there's a lot of scenarios to take into consideration if you're sitting on a Sandy based area and your bed is open on the bottom the water is going to perk straight through with no issues. sand actually allows water to go through it quite quickly clay on the other hand is a compacted material which will hold water again all factors to take into consideration when and thinking about sealing the joints of your bed
