Bales of straw, old doors, pallets, tarps, etc, are suitable. It's best to place the colonies where the morning sun hits the entrances. Make certain there is an uncontaminated water supply nearby. Keep hives off the ground with pallets, old tires, or concrete blocks. Beehives setting on the ground leads to stress from dampness and lack of ventilation.
Heavy bloom is competition for the apple bloom.
Light dandelion bloom will just help feed the bees. This is a short term solution, and pollinizers need to be included in long term pollination planning. However, improper handling of the pollen can quickly destroy the viability. The insert needs to be fed on intervals of a half hour to an hour. There are also self-incompatible varieties that need to be pollinized by another variety.