4x6 is a good size IMO and while I agree that the 8" high beds look better, a well-filled 6" bed is sufficient. If it were me I'd rather spend the money making sure I got good quality filler or another 6" bed than spending it on beds that were deeper.

Dave

zaphod, I have one suggestion ... are you planning to have a trellis on one side of your bed ? If so, I would suggest you change the size because it is hard to reach in more than 2 feet without stepping into your bed. For example, if the trellis is 6 feet long, you will have a hard time reaching into the middle area that is blocked by the trellis. Instead of 4 x 6, you could have 3 x 8 for the same square footage. Or, you can have a 4 x 4 bed with a 4 foot trellis, and you will be able to reach the middle from the front and the 2 sides. Also, I recommend being able to walk around the back side of the trellis.

Several people have been recommending lately to have higher beds. I am increasing the height of my bed this year. I don't know what the cost would be, but you could also consider stacking the bed using two 2 x 6 instead of one 2 x 8.

I hadn't planned on building in a trellis. I'm not sure how we'll be using the space until we give it a go and I want the space to be as flexible as possible. Maybe in the future or on the third bed. That's something to consider about the sizes.

Were there any particular reasons the people gave for recommending higher beds?

Thanks again!

I have 10" tall beds because the soil under them is really bad. It is hard clay with rocks that was brought in as fill. I have to use a pick axe to break it up. No roots will grow down into it. Since my beds are top of this, the entire soil area for roots is whatever is in the beds. 6" deep is okay for shallow rooted plants like lettuce, but many plants need more room for the roots than that (including tomato). Since I do rotate my crops in the different beds, they all have to be able to support the deeper rooted crops. All my beds are at least 10" deep.

If the ground under your beds is halfway decent, you can dig down 4" and amend that soil with compost. Then put your 6" beds on top of that, fill to the top with topsoil/compost/perlite and you will have 10" of great soil - enough for most crops.

I agree that 4' widths are good as long as you can reach into the beds from both sides. You don't want to have to step into the beds to reach any area.

Hope this helps.

Bigger is Better (ask my wife ;-)

Here is a link that might be useful: Raised beds at its finest ;-)

Re: the height of beds ... what feels right for you ... bending over to work in? If you want higher, how about making the corner support posts high enough for your optimum future height. Then build what you can afford this year and add boards to reach the future height as you can afford. I second other's comments about reaching from all sides or if access just from front, reach wi/o stepping on soil.

If the reason for raised beds is because of difficult/impossible soil, the root size of plants you expect to grow will dictate the depth. I like the book linked below .... has pictures showing root depth [by vegetable]at maturity.

Here is a link that might be useful: Root Development of Vegetable Crops

If it was up to me, my beds would be waist high so I didn't have to bend over!!! :) :)

Six inches is fine, remember when you go deeper, you have to find more soil to fill it, which could get expensive.

Yes, most of my beds are 4 feet in width, but those with trellises are only 2 ft. Electrical conduit trellises (make with electrical conduit pipes, 10 ft long) should be 10 ft long.

About the length of the other beds, if you want to save on wood and have more growing area, make them long, and put stepping stones in the middle of the bed every 8 feet. They work well. My longest one (amongst the old beds) is about 30 ft, and the shortest of the big beds about 15 ft. My recent ones are all 10 or 12 ft.

If you have enough beds, you can start thinking in terms of pick-once (say, cabbage) or pick-often (tomatoes). To grow cabbage, bed width is unimportant, since no in-bed work is involved. It's the toms and the zucchini (and the pole beans) that will make you work extra if they are in a wide bed.

Borderbarb,
That is a fantastic study... Thank You for posting it ;-)

You might check out the square foot gardening blog. We make raised beds and plant intensively.
Keski

I agree with Potterhead2. Depth of raised bed soil should depend on the quality of the soil underneath. I, like Potterhead, have more rock than soil. That being the case, 6" isn't enough. I would aim for 10-12 inches in depth, and if you can achieve some of that by digging down, then great. If you stuck to only the top, you'll be happier if you go ahead and raise them higher to begin with. If 6" is all the plant have, I have read on this forum of problems with soil drying out too quickly, as well as top heavy plants toppling over due to shallow roots. I've read many times people who started out with 6" high who have subsequently raised them with a second tier of an additional 6". That tells you that it wasn't working. Personally I built wtih 1"x12" lumber into 4'x8' boxes. I have some bowing, but I'm on my third year with these boxes and am mostly satisfied. If I ever come into some extra money, I'd rebuild with the composite plastic lumber for a more permanent solution, but this is working for me and my budget for now.

Susan

By the way, don't discount the trellis !! I wish I had more trellis space than I do ... on my trellis I plan on growing cucumber, tomatoes, watermelon, canteloupe, honeydew (if I could ever find any seeds!), peas in the spring followed by blackeye peas & green beans in the summer. It's maxed out. If I were growing any winter squash, I would need even more trellis.

The main reason I am raising my bed this year is because I got into square foot gardening late. We had already removed the sod & dug down into our heavy clay & put in a border when I discovered square foot. Since we had already dug down, I decided to kinda improvise my "raised bed" into a "ground level bed" and fill it with 25% each my clay, compost, peat moss, and vermiculite (I had read that clay soil is very nutrient rich). We had a very productive garden last year for being a first time ever gardener. This year, I wanted my raised bed to actually be "raised", and as I want to grow carrots, I am adding another level and filling it with Mel's Mix to the recipe. Plus, after I spent so much last year to startup, it was better to spread the cost of another level to this year, so hubby wouldn't freak out as much. : )

4 foot width is ideal, it minimizes waste in construction. Length is largely immaterial. Whatever fits your space literally and asthetically. My last garden had 16x4 ft beds. My current garden has 12x4. It just takes longer to walk around the end of a longer bed. That said, height matters! My last beds were only 6" tall. My current beds are 10" and 18" tall. I use the shorter beds to plant items that get really tall (ie tomatoes, pole beans, peas.) Everything else is in the taller beds. Your back will thank you! It is amazing how much more willing you will be to weed when you don't have to bend over. Bite the bullet on the cost up front. If you are having soil delivered, the extra amount of product won't really be that expensive. The delivery charge is the same if you get 2 yards or 8 yards.

Also- I left my corner posts exposed above the beds so I can add another 10" if I need to in the future.

I've got 3 raised beds now, and will probably add more in the future. Mine are 4x4 feet, and at my height (5'2") I have no trouble reaching the center of the beds. Any larger and I'd have a problem. Of course, if 4x8 or 4x12 feet work better for your space, that's great. Just make sure you don't have to walk on that lovely soil mix you're creating!

All of my beds are 12" high. Some are 16x20..some are 10x16.

I find it much easier to rotate crops in bigger areas & I use boards as walkways.

My soil is solid clay, soooo...I filled the beds with a mix of 1/3 sand 1/3 clay & 1/3 turkey manure. The PERFECT mix for a cake like texture. I average 300 tomatoes on each of my Early Girl indeterminate's.

I now have 9 beds - mainly because of bad hard soil - as the above post so aptly describes it.

Actually, they run between 3 to 4 ft wide, to 6 to 8 feet long. Because my son works with wood often - (mostly cedar or redwood), so he makes them out of "whatever comes naturally."

Most of them are just 1 x 6 inch cedar boards (cheaper), and then stacked to make 12 inches high. This year (10 years later), I replaced my first one, mainly because of a vole that managed to find a way in, and I discovered that I had failed to nail hardware cloth on the bottom - (10 years ago).

These beds are reinforced with 1 in. x 1 in. posts at the corners - and do not bow in. However, a longer bin might benefit from a brace in the middle of the long side.

If the bed is 4 ft. wide - with the thought of trellising some climbers on the north - long side - I would try to have enough room to work "behind" the bed - you do want to pick those peas and beans - you know, and perhaps have room for a wheelbarrow. Actually, when placing these bins, it is a good idea to think about enough space around them to "negotiate" a wheelbarrow anyway. Because you might want to have enough room to wheel stuff in - or out in the future.

Just my 2 c's.

Bejay

I started out using 1 x 12 inch wood and found that with my very hot summer sun and dry winds the beds dried out very quickly. So I shifted to 2 x 6 inch cedar when I remade the beds and I'm much happier with the results.