Nothing wrong with clay. My mom's been growing in it for years. The only place you run into real problems is when you try to grow root crops.

Annabel,

Welcome! I'm also new to vegetable gardening and also have clay soil under my beds. I think the first question would be, how deep are your beds going to be? If 12" or more I wouldn't worry about your ground soil too much. If less than 12" you may want to work 3 to 5" down. My 8" bed is on 3 to 4" of worked soil and my 12" beds... well the back half of the beds are worked about 4 to 5 " and the front half not at all. Long story. So far everything seems to be happy. You can check out my beds on my blog.

I'm sure one of the more experienced gardeners will give you some good advice.

Enjoy your Garden.

Liisa

Here is a link that might be useful: Liisa's Garden Journey

You should be okay with 6" of soil. We have very hard clay soil and everything is doing great! You could lay the newspaper under the beds, but the plants shouldn't have a problem, if they need to, get their roots down there. The only problem you might have is with carrots.

The first thing you need to do is take a soil sample so you can stop making guesses. Then start amending if it is necessary.

If you start this year for next, you should be good. Consider using the lasagna method. If you feed the worms they will work the soil beneath the bed.

A soil sample would be my first recommendation, and a drainage test the second.

EG

Here is a link that might be useful: EG's Garden Blog

I agree with gumby....

Also, if you want a nice fix over the winter, put some chopped leaves (4"-6" thick) on the bed and work them into the top 6" of soil. Cover with black plastic to keep the soil temp up, and watch how many worms you will have the next spring. I did that this past year with my clay soil bed. I can't count the number of worms I have. Also, the black plastic keeps birds from being able to take away your worms as well. You will protect your worms from predators, and keep the soil warmer, which will allow the worms (and other decomposers) to work longer/better over the winter. The tilth of this bed is FAR better than I ever could have dreamed from where it was when I started (5 years ago).

Thanks for your replies!

I should have clarified in my original post, I am making beds using 2X8 lumber. So, my beds should be a little under 8" high. My main thought is that I'm making raised beds so I don't have to do a lot of soil prep, just making the mix, and so I wasn't sure how important the soil underneath the beds will be in the success of my garden.

So, what I'm hearing is that I should do a soil sample (my location extension service will do one for about $15), and then work about 6" down into the soil? Is a rototiller my best option for that? I'm kind of a weakling, and I'm already struggling to get my boyfriend involved in the gardening project!

You may wish to read through This Thread
before you decide to amend the clay under your raised bed. It's not a good idea unless the lay of the land is such that you can do what's needed to drain any water collecting in the 'bathtub' you would create by amending, away from your bed(s), instead of it collecting right beneath them.

Al

Too much work. Use Mels mix, fill and then plant, simple as that. I have never tested my soil and there is not anything that does not grow in our SFG. Its pretty much the perfect growing medium. Take it easy, dont make it complex. Thats the idea behind the second SFG book, unless, of course, you want to do the extra work!

annabel, You gave no time frame to work with.

I think the only reason to do a soil test is to establish a baseline. So YOU know what you started with. Esp. if you run into problem later. After site selection the next step should always be a soil test. If you fail to do it now, you will have no idea where you went wrong later.

I wouldn't bother tilling. In fact, I sold my tiller the year I started SFG. As for amendments, I would pour a lot of money into it. If your soil test shows it won't support plant life, well then you have to regroup but you saved yourself a bunch of time and money. If you are a weakling you should be reading up on lasagna gardening.

The roots from your plants will reach down beneath your bed AND out into the pathways too. Some travel 10ft or more. If you need to amend, you can add small amounts out in the walkways. Add leaves in the walkways to keep weeds down, the soil moist, and feed the worms.

The mix and any amendments will leach down in time but it will take time. Don't get heavy handed with fertilizers. Use compost and compost teas and you will be pleasantly surprised. Worms don't like ferts.

The suggestions above to get the worms to loosen the soil for you, are excellent and do work. Feed the worms and they will feed your plants.

ps. do NOT get all excited when you see bugs in your garden. That is where THEY live, you are on their turf. Most you will see are good guys but will still creep you out. If you start spraying stuff - you will kill the good guys and pollinators along with the bad boys. This creates an imbalance for the bad guys to take over. So be patient here. Remember you need the pollinators.

The biggest advantage of having your own garden is so you know exactly what has been sprayed on what you will eat.

You can easily grow peas, beans, lettuce and short varieties of carrot in 6-8" of soil. Tomatoes maybe able to grow in shallow soil but they will not be at thier best. I usually plant my tomato plants 6-8" deep when transplanting them out, that would not leave the roots anywhere to go. I would not plant a tomato plant in a 8" deep pot. If you want to grow longer varieties of carrots you will need deeper soil. I have not grown potatoes but I don't think 6-8" would be deep enough to get a good crop. Potatoes grow off the stems that are underground, the deeper they are the more stem underground the more potatoes to harvest.

Just my 2 cents worth, I think that roots are the most important part of a healthy strong plant. Most will grow alot deeper than you would think if given somewhere to go.

Good gardening, Mary

I put my beds on grass...after 2-3 years the earthworms have loosened the soil beneath the original grass line so you can't see much difference compared to what's above it.