10 BULLETIISr 392, U. S. DEPARTME]SrT OF AGRICULTURE. 



uniform in composition, density, and in the amount of heat produced; 

 (2) a frame with the rear board 4 to 6 inches higher than the front 

 board, and (3) glass or cloth covers for the frame. For a permanent 

 hotbed an excavation or pit 24 to 30 inches deep should be made. 



Sowing seed : Sow the seeds in rows 3 to 4 inches apart, one-fourth 

 to one-half inch apart in the row, and cover about one-half inch 

 deep. Water the surface of the soil with a sprinkling can. Keep the 

 hotbed covered with sash or cloth. Raise the sash during the heat 

 of the day for ventilation. Water the bed in the morning on bright 

 days. 



Cold frame: (1) The uses of the cold frame are (a) the growing of 

 vegetables for winter use, (b) the hardening off of the more delicate 

 plants in early spring, and (c) starting semihardy plants, as cabbages^ 

 cauliflower, etc. (2) The points determining the location of the cold 

 frame are (a) protection from north wind such as the south side of a 

 building, fence, or hedge, (b) nearness to ample water supply, and 

 (c) southern or southeastern exposure. (3) Materials for making a 

 cold frame are (a) a frame with a board 12 to 16 inches high on the 

 north side and 6 to 10 inches high on the south side, (b) glass, canvas, 

 or cloth covers, and (c) very rich, thoroughly pulverized soil. 



Study questions : What are the advantages of hotbeds ? How are 

 they made? What is the difference between a temporary and a 

 permanent hotbed ? Which kind is most commonly used in the com-, 

 munity ? What plants other than tomatoes are started in hotbeds ? 

 Is glass or cloth used for covers ? What is the difference between a 

 hotbed and a cold frame ? For what are cold frames used ? To what 

 extent are cold frames and hotbeds used in the community? Are 

 cold frames used to harden off tomato plants ? What other plants are 

 grown in cold frames ? 



References. — Farmers' Buls. 642, pp. 1-3, pp. 12-15; and 460. 



Practical exercises. — (1) Club members and pupils with home work 

 should prepare a compost heap under cover and thorouglily rot the 

 manure to be used in preparing soil for the hotbed. Manure for 

 furnishing heat for hotbed should be fresh, as well-rotted manure 

 does not give off heat. (2) Make frames for the hotbed and for the 

 cold frame. (3) Make the hotbed and prepare to sow tomato seed. 



Correlations. — Have the members of the class describe the hotbed 

 used in starting their tomato plants. 



Drawing: Draw the frame to scale. 



Ai'ithmetic : If tomatoes are planted in rows 4 feet apart and stand 

 3 feet apart in the row how many plants are required to set one-tenth 

 of an acre? If each plant occupies 2 square inches in the hotbed 

 what should be the area of a hotbed sufficiently large to produce 

 plants to set one-tenth of an acre ? Find the cost of material including 

 the cover to make such a frame. 



