I should think sand is lacking in both fibre/texture and nutrients. Texture is required to protect and stabilize roots and nutrients to provide growth. Two options that come to mind are 1) go with container/box gardens where you put in a good growing mix 2) start working compost material into your existing garden site. The first method will require some effort and dollars but doesn't take long to set up and you could do a same season planting; the second method is going to take longer to get going and will probably always require adding compost to keep it maintained but on the bright side it needs less financing up front.
I have a problem with clay where I am. It turns hard as rock if not maintained with compost material and diligent rototilling. Composting material has been a great help for me.
I wish your daughter success with the garden venture.
Sand doesn't have nutrients and microorganism that plants need to survive.
I agree with above. I would suggest building raised beds (cinder blocks or 2x6 boards) and fill with compost and top soil.
Organic mushroom compost around here isn't that expensive, about $150 for a medium sized trailer load.
Plan on next year and pile up stall leavings. This will cost you nothing but sweat equity. Horse manure takes 4 months to break down outside and be usable to amend soil. Sand is a good additive for clay, but compost, which can be stall cleanout, the manure with the soiled bedding contains a plethora of microorganisms, fungi and small critters that feed plants and it is loose, to allow for roots to spread easily.
Don't till it, just rake and fluff it and it's ready for use.
Honestly, gardening is a science, which I've learned from several forums and my personal experiences over the last decade--I AM NOT MASTER GARDENER!!--but I grow/harvest tomatoes, beets, okra, peppers and potatoes every, and I've had squash and pumpkin harvests. They can be killed off by parasites, but that's another story.