8 MASS. EXPERIMENT STATION BULLETIN 358 



large enough to place the roots without crowding and deep enough to put about 

 an inch of the stem below the soil surface. 



Blueberry varieties are self-unfruitful, or nearh' so, under some conditions. 

 Therefore, it is best to plant at least two varieties. They should be set in alter- 

 nate rows if they are equally desirable. If not, at least ever>- fourth row should 

 be different. 



Soil Management 



Blueberry plantings are usually kept cultivated from early spring till about 

 mid- August. Cultivating after that may cause late growth and make the plants 

 susceptible to winter injury. 



Since blueberries are shallow-rooted, cultivation should not be deep, especialh- 

 close to the plants. As a result of their e.vperiments in New Jersey, Beckwith 

 and Doehlert (2) recommend cultivating to an average depth of three inches 

 between the rows but no nearer to the plants than the ends of the branches. 

 To check weeds close to the plants, they advise hand hoeing or very shallow cul- 

 tivating with an acme harrow. This agrees with experience in Massachusetts 

 that tillage is necessary to keep the soil from becoming packed and poorK- aerated 

 but that deep cultivation close to the plants is harmful. 



A mulching system for blueberry plantings has been satisfactory in some 

 places. This makes cultivation unnecessary, adds organic matter to the soil, 

 and conserves moisture. But mulch may be costly and hard to get, dry mulch 

 is a fire hazard, and some mulches greatly increase the danger of injury by mice. 

 Pine needles, fallen leaves, and peat are all excellent mulching materials. Saw- 

 dust or shavings may be used. Straw and waste hay are too attractive to mice. 

 Enough mulch should be used to keep weeds down. 



Fertilization 



Blueberry plants respond readily to fertilization. Although nitrogen generally 

 afTects growth and yield most, experiments in New Jersey (2) indicate that a 

 complete fertilizer is desirable because nitrogen used alone causes excessive shoot 

 growth. 



Young blueberry plants are easily hurt by too much fertilizer. No fertilizer 

 is needed the year the plants are set. A small handful well spread cut around 

 each plant is enough the year after planting. The ne.xt year a little more may 

 be used. The fertilizer is less likeh' to cause injury if it is mixed with about three 

 times its weight of dry sand to facilitate spreading. 



The third year and thereafter the fertilizer can be scattered broadcast between 

 the rows and the amount gradually increased till five or six hundred pounds per 

 acre are used when the bushes begin to bear. This heavy fertilization of the 

 bearing bushes is recommended because vigorous shoots produce the largest and 

 best berries and because abundant growth is needed to replace the wood removed 

 in pruning. 



The following mixture, which anal^•se^ about 7-8-7, is recommended: 



Nitrate of soda 450 pounds 



Calcium nitrate 450 pounds 



20% Superphosphate 800 pounds 



Sulfate of potash 300 pounds 



Since the New Jersey Agricultural Experiment Station has obtained very good 

 results by splitting the fertilizer application, it is recommended that half the 

 fertilizer be applied the middle of Ma\- and (he rest three weeks to a month later. 



