If weeds are allowed to compete with the young plants for the first couple of years, blueberry growth will be stunted greatly, and you will not have a strong orchard in 3 to 5 years. Research at UGA has shown that a weed-free area around newly planted blueberries of 16 ft2 provides optimum overall growth and flower bud number. With plants spaced 5 ft in a row, this would be accomplished by having a weed-free band roughly 3 ft wide. Consult Extension publications or your local Extension Agent for registered herbicides, and always read the label. Another important consideration for establishing a new planting of blueberries is irrigation.
Young plants benefit greatly from supplemental water.
In fact, without irrigation a number of plants can be lost the first year of planting if the weather is dry. Drip irrigation, trickle tubing, and over head sprinklers are all commonly used to provide water to young plants. Decide what sort of water supply you have available, and create an irrigation system that compliments the water supply. It is not wise to plant more blueberries than you can irrigate the first couple of years after establishment. Of course, you need to be careful not to over-water young blueberries as well.