You need to decide what future modifications you want to plan for. I don't think there is a dimension which will suit all purposes exactly.

House framing is done on center to center intervals based on 48" such as 12", 16" and 96". This coordinates with the standard widths of sheet materials such as plywood and insulation, which can be attached to the framing or installed between framing members without cutting to fit. Will you be attaching sheet materials flat across the beds and fastening the edges to the raised beds? If so, make the overall width (out to out) 48". But I doubt that is what you want or need. More likely, you will want to use row cover or something of that nature, which is variable in width depending on how much height is needed.

Do you expect to expect to use cold frames? Are you saying that ready made cold frames you might use are available in a standard size? Or would that be a convenient size to build yourself? If you can plan for a particular size, building to fit the cold frames would be smart.

Jim

g'day steve,

usually the beds are around the 3' to 4' (1 meter) wide, this so you can reach into the middle from either side. don't think the measurement would be too much different from the outside of the edging or the inside unless you are using this cement block which are quiet wide them selves, then i would make the outside width the maximum width of the beds.

len

Here is a link that might be useful: Lens garden page

Well, I do plan to make cold frames myself and I want those to fit tightly on or inside the raised beds. I just don't want to end up needing to cut materials to wasteful sizes like a bunch of 51 inch pieces. Maybe I should think about the gable ends of the cold frames. If I want to use plywood for those triangles then it would probably work out best to limit the width of the cold frames to exactly 48 inches. I'm thinking I'll go with exactly 48 inches between the walls and make the cold frames so that they will slip down inside the edges of the raised bed.

Steve - I have to admire folks who plan things ahead.

When I started gardening in boxes - about 15-20+ years ago, my only thought was to make a "box." Now some years later, I find it might have been practical to make all 9 of them the same size. In that regard, I might have used the same cages - that became necessary to "protect" the plantings.

So - I have a hodge podge of boxes, cages, screens, etc., that are OK. But it certainly would have been a lot easier, if I had planned ahead.

Go for it.

For instance, I made some PVC pipe cages - that needed to be surrounded with wire - originally I used chicken wire. It isn't very nice - especially when one has to cut it to size - leaving loose edges (catches fingers, arms, etc., when reaching insdie). Sooo - yes - hardware cloth - for instance, comes in standard sizes. So making a cage out of it, would be best at 36 inches - and enough to fit INSIDE the box. That way, it would be 3 feet high - enough to keep out critters, and allowing the plant enough height room.

The cage frame was made out of PVC water pipe - to fit INSIDE box, with the hardware cloth wrapped around it.

So - hopefully this isn't too off-topic, but just thought I'd let you know how nice it would be if one plans these things ahead of time. I really admire you for thinking ahead.

Bejay