Answer: Really good garden soil takes a few years to build. The steps you've taken so far are good; expect to add organic matter to the soil each spring, both to improve the tilth of your sandy soil, and to provide nutrients to the roots of the plants as the organic matter decomposes. Your summer season is long enough that you should be able to to successfully grow cucumbers, cherry tomatoes (or short season regular sized tomatoes), carrots, lettuce, crookneck or patty-pan summer squash and radishes. Peppers take a really long season to mature so you might be disappointed in their productivity if you plant them now (in July). If you can get your hands (or wheelbarrow) on some aged-compost or aged-manure, spread 3"-4" over the soil surface and dig it in before planting. In the autumn you can sow a cover crop such as vetch and plan to dig it into the soil in the spring prior to planting your garden. The vetch will trap and hold nitrogen in its roots. When you plow it in, the nitrogen will be released into the soil for use by your spring crops.
Good luck with your new garden!
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