I had the same dilemma when starting plots in a community garden. I ended up adding composted horse manure (it was provided for free but you can usually find it pretty cheap on craisglist), perlite, peat moss, green sand, bone meal, and a somewhat nominal amount of coffee grounds from Starbucks. The main thing seemed to be mixing it really well with the sand - I wet it and re-dug it about 3 times so that I didn't just have spots and layers. I think in the future, I would add some pine bark fines too. I used only about 1/2 a bale of peat moss for about 175 square feet, but about 25 wheelbarrows of manure.

Hi Chuck

First I like to say that it is your garden and you can do whatever you want.:)
If it was me, I would not be mixing the sandy soil with anything that I add, that soil has no nutrients and maybe nematodes?
Pretty much you can use anything in a lasagna type style bed. I would not use perlite because it will add nothing to the soil, in containers the purpose is different.
My beds have a lot of organic material that I keep replenishing after the season is over and when planting I add the proper fertilizer according to what I am growing. Peat moss and black cow are good for my small garden.
Another style and that is also working in the community gardens is to get the free mulch from the city and put on top of the sandy soil.
Hope that you make the right choices for you and make a productive garden beds.

Silvia

I agree with Silvia,in that I would build on top of the existing soil.I built a number of 50 sg ft(10x5) raised beds that are 12" high.Unlike your soil,I have a lot of clay in mine,so I double dug each bed to help with drainage.I then added #1 grade topsoil to each bed & worked some composted manure into the top few inches of the bed.You will save a lot of $$$ & lifting if you can borrow a low sided trailer.I bought all my topsoil from a landscape supplier & 1 cubic yd cost $19.For the most part a yd would almost fill the 10x5 beds(they always give extra when loading).You could look into getting the topsoil delivered,but I'm sure they will have a minimum amount of cubic yds,before they will deliver.Best of luck

Many localities have free or cheap composted yard waste. Check with your local sanitation department.

As Silvia said.... Lasagna gardening is the way to go. Much less labor intensive and the earth worms over time will carry the organics down. Just keep adding every season.

Here's what I would do (and did do!). Since there's not much for you to grow this summer, this is a great time to work on soil prep for your fall garden. Plant a ground cover. I chose sun hemp, because it can handle the heat, repeals nemotodes, and is a nitrogen fixer. You may find something else you'd prefer, but I found it did everything I needed it to do and grew quickly. This would be a perfect time. Then you cut it all down in August, before it goes to seed. Don't till up the roots, just cut it down and let it lie. Then do layers of materials. I did compost, coffee grounds from Starbucks, alfalfa pellets (from feed store for horses), leaves, kitchen scraps, peat moss, and black kow.

In zone 10, you won't be able to start your fall garden till Oct. most likely. So, that will give you a month or two for everything to settle. Then you plant in those layers of goodness. I had really good luck my first fall with that recipe. Good luck to you.

Becca