TEMPERATURE AND LIGHT. Iig 



grower. Repeated trials in growing radishes in large 

 houses having different temperatures have shown plainly 

 that during the first two or three weeks, at least, radishes 

 will bear well a soil temperature of fully 65 F., and 70 

 has not proved too much in several instances. If suffi- 

 cient moisture is present the plants must grow, and they 

 must mature quickly. 



But although a high soil temperature is desirable, it 

 does not follow that the atmosphere should be equally 

 warm. On the contrary, if the temperature of the house 

 can be kept about 10 degrees below that of the soil, the 

 tendency to leaf formation will probably be checked. The 

 hotbed may again serve as a guide. Here the heat is in 

 the soil, bottom heat, as it is called, and the large amount 

 of glass, as compared with the amount of air-space, must 

 have a strong tendency to lower the temperature about 

 the foliage ; that surrounding the roots is much less af- 

 fected. 



Another important point, one which has not been 

 duly emphasized in connection with this crop, is the 

 amount of light received by the plants. Few plants show 

 the want of light more quickly than radishes. If the 

 shadow of a steam pipe or of a board falls upon the 

 bench, the plants soon become drawn ; the shadow cast 

 by tall-growing varieties causes the shorter ones to grow 

 more upright ; a roof having small panes of glass and a 

 comparatively large amount of wood-work has a strong 

 tendency to prevent the plants from forming bottoms, un- 

 less the glass is close to the foliage ; and if no direct sun- 

 light is allowed to reach the plants, no swelling of the 

 stem may take place, but the plants will grow very slen- 

 der, and finally die, as if attacked by some unknown 

 malady. If radish seed is sown very thickly, a similar re- 

 sult may occur even in places which are fairly well 

 lighted. The strong growth of foliage excludes practi- 

 cally all the light from the soil, and the plants will form no 

 bottoms. 



