We have been pollinating almonds in California for over 6 years now. A couple of things to consider when renting bees for almonds are your crop density and the competition to your trees. While, almonds are pollinated by the wind as well as other insects, in heavily cultivated areas it is best to supplement this with honeybees, due to low native insect population and the wind can not be relied on completely as the rain that usually accompanies it can wash away a lot of the pollen and knock off blooms. Generally the weather is not very good during the times of pollination and your best insurance to a good crop is honeybees, as they will take advantage of the good weather and get the pollination done. It is best to try and eliminate potential competition to your trees by keeping the weeds down in your orchard as well as talking to your neighbors about cutting any weed fields that might be near you. Other orchards near you can also be competition to yours if they do not place bees, and you might need to either use more hives or really strong ones. Generally placing the bees in your orchard when it is at 10% bloom is best because the bees will go to the nearest food source and stay with that source until it is depleted, meaning that if the bees go to weeds instead they will stay with those weeds and ignore your trees for a time. Generally if your orchards are not double planted and competition is limited, 2 to 3, 6 frame hives per acre is good (1). Pollination Specialists have said that over pollination could be a bad thing, honeybees will take as much nectar as possible from the trees, draining them of essential energy to set nuts before they can replenish it after pollination when the trees have leafs, so it is important to have the correct amount of bees for the correct amount of time (2). The time requirements very depending on the weather and how the trees look. For more information you can visit these pages.