DIRECTIOlSrS FOR BLUEBERRY CULTURE. 9 



(10) After the new twigs have stopped growing and their wood becomes 

 hard new root growth takes place. Then secondary twig growth follows, either 

 from the apex of the new twigs or from another bud lower down on the old 

 wood of the original rooted shoot. Until this secondary twig growth takes place 

 the life of the plant is not assured. 



SOIL MIXTURES FOR BLUEBERRIES. 



A very successful potting mixture or nursery-bed mixture for blue- 

 berry plants consists of one part, bj' measure, of clean or washed sand, 

 nine parts of rotted upland peat, either chopped or rubbed through 

 a sieve, and three parts of clean, broken crocks — ^that is, pieces of 

 ordinary unglazed, porous, earthenware flower pots. No loam, and 

 especially no lime, should be used. Manure is not necessary, and in 

 the present state of our knowledge may be regarded as dangerous, 

 although in small quantities it serves to stimulate the plants, at least 

 temporarily. The danger from manure apparently lies in its ten- 

 dency to injure the beneficial root fungus of the blueberry plant. 



The use of broken crocks in the potting mixture is based on the 

 fact that the rootlets seek them and form around them the same kind 

 of mats that they form at the wall of the pot, thus increasing the 

 effective root surface and the vigor of growth. If crocks are not 

 available, the soil mixture should consist of two to four parts of peat 

 to one part of sand. 



The peat most successfully used for potting blueberry plants is an 

 upland peat procured in kalmia, or laurel, thickets. In a sandy soil in 

 which the leaves of these bushes and of the oak trees with which they 

 usually grow have accumulated and rotted for man}^ years, untouched 

 by fire, a mass of rich leaf peat is formed, interlaced by the superficial 

 rootlets of the oak and laurel into tough mats or turfs, commonly 2 

 to 4 inches in thiclniess. These turfs, ripped from the ground and 

 rotted from two to six months in a moist but well-aerated stack, 

 make an ideal blueberry peat. A good substitute is found in similar 

 turfs formed in sandy oak woods having an underbrush of ericaceous 

 plants other than laurel. The turfs of lowbush blueberries serve 

 the same purpose admirably. Oak leaves raked, stacked, and rotted 

 for about 18 months without lime or manure are also good. The 

 leaves of some trees, such as maples, rot so rapidlj' that within a j'ear 

 they may have passed from the acid condition necessary for the 

 formation of good peat to the alkaline stage of decomposition, which 

 is fatal to blueberry plants. Even oak leaves rotted for several 

 years become alkaline if they are protected from the addition of new 

 leaves bearing fresh charges of acidity.*^ The much decomposed peat 



« For a fuller discussion of tho conditions under which leaves decompose into leiif peat 

 as distin^juishod from leaf mold, and the fundamentally different effect of the two on the 

 growth of plants, consult " The Formation of Leafmold," Smithsonian Report for 1913, 

 pp. 333 to 343 (also separately printed). 



