Yearboo^ of Agriculture 1949 



late as July. Some may be sown either 

 in the spring or fall; early fall sowing 

 and immediate germination are desired 

 for others. Each species must be given 

 individual consideration to secure the 

 desired size and development. Seed of 

 some species sown in the fall does not 

 germinate until warm weather comes 

 in the spring. 



Some of the species that require fall 

 sowing or stratification are white pine, 

 spruce, redcedar, juniper, and the nut 

 and stone species of the broadleaf trees. 

 Longleaf pine seed is sown in October; 

 it germinates promptly and by mid- 

 December the seedlings are well estab- 

 lished. Jack pine and shortleaf pine 

 are sometimes sown in late June for 

 transplanting the following spring or 

 are left in place for another year. In the 

 South, shortleaf, loblolly, and slash 

 pines are sown in March and early 

 April. Farther north, spring sowing is 

 done in April and May. Hard-seed- 

 ed species are sown in the fall for 

 early spring germination, or they are 

 stratified or otherwise treated to in- 

 duce germination and sown in the 

 spring. Cottonwood seed must be 

 sown shortly after it is collected, other- 

 wise it will suffer serious losses in 

 germinative capacity. 



Presowing treatment to break dor- 

 mancy is necessary for some species. 

 Stratification consists of placing the 

 seed in a moist medium, such as peat 

 moss, sand, or sawdust, and keeping it 

 at temperatures ranging from 32 to 

 41 F., for periods varying from 2 

 weeks to 2 months. This treatment is 

 substituted for fall sowing. A method 

 used to break dormancy of species with 

 impervious seed coats is to remove a 

 portion of the outer coat with acid. 

 Black locust, honeylocust, soapberry, 

 and coffeetree are sometimes treated 

 in this manner. Scarification, that is, 

 the reducing of the thickness of the 

 seed coat by mechanical means, is 

 sometimes used in place of the acid 

 treatment. Ash, mulberry, Osage- 

 orange, and catalpa respond to soak- 

 ing in water before they are sown. 



As far as possible, all seed is sown 



by tractor-drawn seeding machines. 

 Some seeds are so irregular in shape or 

 size (because of out-growth and ap- 

 pendages) that they cannot be sown 

 with a machine and must be sown by 

 hand. All conifer and many broadleaf 

 species are sown mechanically. Cotton- 

 wood, oak, walnut, and ash are some 

 of the seed sown by hand. 



The seed cover for the germination 

 period varies with the type of soil, cli- 

 matic conditions, and the species. In 

 the northern regions, sand is used to 

 cover conifer seed where the soil con- 

 tains a high percentage of clay, other- 

 wise native soil is used. In the South, 

 burlap is used extensively for cover 

 during the germination period. Pine 

 needles or straw may be substituted for 

 burlap with good results. Mulching to 

 prevent frost heaving is a requirement 

 for fall-sown seedbeds in the northern 

 nurseries; straw held in place with 

 wide mesh wire is commonly used. 

 Where the frost heaving is severe, the 

 older seedlings and some transplants 

 must be covered. 



Hardwood seedlings, with few ex- 

 ceptions, are grown without mulching. 

 In the heavier soils where crusting is 

 serious, the seed is covered slightly 

 deeper and, when germination starts, 

 the excess soil and crust is removed to 

 permit the seedlings to emerge nor- 

 mally. A light mulch cover of straw, 

 pine needles, or leaves is sometimes 

 used to keep the soil surface moist and 

 prevent the formation of a crust. 



The density of seedlings in seedbeds 

 varies from 4 to 100 to the square foot. 

 Those to be shipped as seedlings are 

 given sufficient space for optimum de- 

 velopment. The seedlings to be trans- 

 planted after 1, 2, or 3 years are grown 

 at greater densities to reduce their cost. 

 Broadleaf species usually are shipped 

 as 1 -year-old seedlings, but most coni- 

 fers must be left in the nursery for 2 

 to 5 years. 



Great care is taken to obtain proper 

 density. Germinating a large enough 

 sample of each lot of seed is standard 

 practice to determine the number of 

 seed to sow. Seed changes in germi- 



