SEED SOWING 133 



of onions is very slow and tedious, and therefore great 

 care should be taken to sow just the right amount of 

 seed. (8) Ravages of insects. Insects are usually very 

 destructive to certain plants, as melons and cucumbers, 

 and by using plenty of seed there will be greater cer- 

 tainty of saving enough plants to make a satisfactory 

 stand. It generally pays to use seed freely and to thin 

 when necessary. 



193. Thinning. This is an important operation in 

 growing many garden crops, and it is often practiced in 

 starting plants under glass, but more frequently in open- 

 ground culture. Thinning is a process of selection ; the 

 weakest plants should be discarded, and only the most 

 vigorous left to mature. This is one of the strongest 

 arguments for thinning. Thinning secures a uniform 

 stand. Because the operation is tedious and expensive 

 successful gardeners endeavor to avoid it as much as 

 possible by the even distribution of the proper quantity 

 of seed. 



194. Depth of sowing. There are no infallible rules 

 to determine the proper depth for sowing. Certain 

 writers have advocated the regulation of soil covering 

 by the diameter of the seed ; that is, by making the cover- 

 ing two, three or four times the diameter of the seed. 

 Such rules may be of some value when sowing in the 

 greenhouse or hotbed, where moisture and soil conditions 

 are under control, but they are likely to be misleading 

 when applied to field conditions. The size of the seed 

 should be considered, and also the character of the soil. 

 In light, sandy soils the depth might be several times as 

 great as in heavy soils. Summer and early fall sowings 

 require greater covering than early spring sowings, be- 

 cause the surface layer of soil is drier, and it is necessary 

 to place seed at a greater depth to secure the necessary 

 amount of moisture. Some of the smallest seeds, as 



