There is another ongoing thread just a few below the one you started that discusses this:

https://www.gardenweb.com/discussions/5637069/best-soil-for-hedge-plants-grown-in-raised-beds#n=15

Hope it helps!

To simplify the long and involved discussion linked to above, a raised bed is just a elevated garden planting bed.....so you just want to fill with garden soil and one that is well amended with some fertile organic matter. Of your choices, #2 is much better than #1....but not ideal (too much compost and no need for sand). Better would be 75% topsoil or garden soil and 25% compost.

A 4'x8' bed that is 12" deep will take over a cubic yard of soil so it is far less expensive to buy a bulk soil product if you need to import the soil to fill rather than purchasing any bagged product ($50-75 for a cubic yard of bulk soil compared to $5-9 for a cubic foot of a bagged product.....and you'd need 27 of them!!). A landscape or garden planting mix or raised bed soil mix should be available anywhere that sells landscaping supplies and bulb soils and mulches.

You may still need to add fertilizer at some point during the growing season but that is never a given so it makes no sense to give some arbitrary formula for what and how much to apply now. Even the occasional application of Miracle Gro via a hose-end sprayer will suffice.

If I were to use the raised beds, one of the crops I would plant in them would be tomatoes, peppers, and eggplants (not necessarily all in the same bed).

When Preparing Tomato bed apply 3 lbs. of tomato tone per 50 sq feet and work into top 4”-6” of soil.

I found a PDF for tomato tone, and these are the instructions it gives for how to use it:

For Single plants mix 3 T (tablespoons)of tomato tone into the soil when planting

For potted plants, mix one part tomato tone to 30 parts soil mixture (1.5 cups tomato tone for every 8 quarts of soil)

FEEDING:

Apply tomato tone after plants are well established (10-14 days after planting) and then twice a month during growing season (May-Aug)

ROWS: 1 cup each side per 5’ of row

Single Plants:3 T per plant

Potted plants: Apply 1.5 t per 4” diameter pot (1.5 T per 12” diameter)

The thing I am confused about is it doesn't give any instructions for how much to use in a raised bed; the closest I get is 'apply 3 lbs. per 50 sq feet'. Is the area of a raised bed (by 'area' I mean how much soil it can hold) square feet or cubic feet? I am pretty sure it's square feet, but I can't remember, so I wanted to double check to be sure.

Also a really dumb question but what do you mean by 'top soil'? There are bags labelled 'top soil' and other bags labelled 'potting mix' (potting mix would more akin to miracle gro/something similar). Which one should I use?

Also how much can you actually grow in a 4' x 8' raised bed with plants? I realize this depends on what you're growing in the raised bed but for me it'd be veggies. The veggies (no I am not growing to grow all of them at once nor am I going to grow all of them in the same bed) would be:

*Greens (lettuce, spinach, arugula, watercress, baby kale)

*Brassicas (cabbage, napa cabbage, cauliflower, broccoli)

*Root veggies (turnip, daikon [large white Asian radish], carrots, potatoes)

*Zucchini

*Winter squash (only one variety, butternut)

*Tomatoes (slicers, cherry, and romas/paste) (please specify how many plants, both trellised and untrellised I'd be able to grow in a 4' x 8' bed; most of mine are indeterminate varieties, but some are determinate varieties, specifically the cherry tomatoes)

*Eggplant

*Peppers (both sweet bell and hot chile varieties)

*Snap beans (bush type)

*Snap Peas (both pole type and the variety that don't require trellising)

*Herbs (flat leaf parsley, rosemary, basil, culantro [it's similar in flavor to cilantro but it's NOT cilantro, it's much stronger in flavor])

Also I am wondering, can you grow corn in a raised bed? I know it's generally not advised to grow it in a raised bed, but the variety I have is a dwarf type (by dwarf, it's 2'-3') and says right on the pkt that it can be grown in containers.

Admission - I didn't read anything but the OP.

You're going to want something with enough mineral content that it doesn't break down in a couple of years and gas off as CO2, leaving you with an amazing amount of shrinkage.

This ^^ is what's in my raised beds and it's amazingly productive. Tilth is excellent. Anything I've added over the years (pine bark), has been added as a top dressing to avoid N immobilization. It's made of Pine bark, Michigan (reed/sedge) peat, unscreened Turface MVP, pine bark, builder's sand. I wish I'd have added more inorganic material when I made it, but over the years I've corrected that issue by dumping used gritty mix from my bonsai repots onto the beds.

Al

Raised beds with open bottoms just need topsoil that is mostly mineral soil with 5-10% organic matter. So sandy loam.

I agree that's all that's needed, but I can say that what I've been observing is remarkably superior growth compared to what's in the soil in the rest of my yard, which is the same as what's under the 8" deep RBs ..... and I'd rate that soil as excellent. You can see that things aren't suffering much in the underlying soil.

Al

Of course plants grow more vigourously when they have a surfeit of nutrients but too much organic matter just leaches those nutrients into the ground water.

There's nothing in the beds that can't be found in a forest. No guilt here.

Al