Brand new to gardening.
Recently setup a 3.5'x4' above ground garden with some herbs, peppers, and tomatoes. Ground soil is mostly sand (Living in Orlando, FL). How do I ensure the bed maintains proper hydration? When I put down the top soil I used 3 bags, which was supposed to give me 4" height per every 2' x 2' area. However, it seems there's not nearly enough soil for anything to sustain anything.
I am glad you used potting soil. That should be more than enough to maintain moisture. Do you mean that your raised bed didn't get filled up to the top of the sides? Potting soil is exactly what you needed to use. Potting soil has very little actual soil in it, is that what you are worried about?
You have no worries about holding onto moisture. You do not want to add garden soil with clay, or any water holding sponges or gels. I would use decomposed compost to mulch around your plants on top of the potting soil. Make sure the compost is not manure based; too much nitrogen for your plants. Do use extended release balanced fertilizer for vegetables.
Being in Florida I would also have a 'shade' cloth, its black and only 10% shade mesh would be necessary for extremely hot days (over 85 degrees F) to cover. Even the white floating row cloth would work as a temporary cover for excessively hot days. When the wind gets blowing I would also cover my plants with either fabric.
Water well before planting starts. If you plant seeds do not soak the soil deeply, just the surface needs to stay moist until the plants have some height on them and deeper roots. Then water deeply and allow the top inch or two to dry before watering again. The plants themselves will help shade the soil when they mature.
You really need a foot of soil depth. Four inches won't cut it. It just won't supply enough nutrients for the roots, and if they reach into the base sand, there's just not enough nutrient there.
Normally you would use something like potting mix instead of topsoil because the topsoil won't drain properly, and you might have problems with roots rotting. Although sitting on top of sand the topsoil has greater capillary pressure to prevent water from draining until the topsoil becomes saturated.
Your raised bed is like a large pot and you need to water it more frequently than if planting in the ground. You can use moisture meters or just stick your finger into the soil mix.
