186 GREENHOUSE MANAGEMENT. 



and fifty feet wide are not uncommon and prove 

 satisfactory. The lean-to lettuce house described in 

 Greenhouse Construction is cheaply constructed and 

 gives excellent results, particularly if built upon a 

 side hill, but the three-quarter span house is sup- 

 planting it in some localities, and will be found 

 preferable for houses upon level ground that are more 

 than thirty feet wide. The benches may be either raised 

 or solid, a common plan when three beds are used in 

 houses twenty feet wide being to have one solid bed in 

 the center and raised benches at the sides, or the ar- 

 rangement may be reversed. In some of the large 

 houses, even if as wide as thirty-three feet, one solid bed 

 is made in the center, leaving only space for narrow 

 walks next to the walls, but a center walk in addition is 

 desirable. Solid beds raised one or two feet above the 

 walks, and not more than fifteen feet wide, are generally 

 preferred to raised benches. 



In many sections where fuel is cheap, the old-fash- 

 ioned flue is still used with good results, and in fact a 

 large per cent of Grand Eapids lettuce is grown in flue- 

 heated houses. Steam is also largely used, and the heat- 

 ing plant is cheaper than hot water to put in, but, even 

 in large houses, hot water in small pipes is preferred by 

 many who have mad6 a careful test of the two methods. 



COMMERCIAL LETTUCE GROWING. 



With good management, three or four crops of let- 

 tuce can be harvested, and the houses can then be used 

 for the growing of vegetable plants, cucumbers, or toma- 

 toes. It is desirable to have the first crop come on by 

 Thanksgiving, or before, and for this purpose the seed 

 should be sown in an old cold frame, or in a seed bed 

 outside, especially prepared for the purpose, about the 

 last of July or first of August. The bed should be 

 marked off into rows six inches apart, and the seeds 



