54 GARDENING FOR PROFIT. 



covering up at night, and in giving air during the day. 

 It often tiappens that a few mild nights in March. or April 

 delude us into the belief that all the cold weather is over, 

 and the covering up is in consequence either carelessly- 

 performed or abandoned. Every season shows us scores 

 of victims to this mistake, who, by one cold night, lose 

 the whole labors of the season. It is always safest to 

 cover up tender plants, such as Tomatoes, Sweet Pota- 

 toes, etc., until the 10th of May in this latitude, and the 

 more hardy plants, such as Cabbage, to the 1st of April, 

 when raised in hot-beds ; even if there is no danger from 

 freezing, it will give a more uniform temperature, and con- 

 sequently conduce to a more healthy growth. The want 

 of close attention in airing is equally dangerous ; often an 

 hour's delay in raising the sashes, will have the effect of 

 scorching up the whole contents of the hot-bed, and ir- 

 regularity of airing will always produce " drawn " and 

 spindling plants, even when they are not entirely killed. 

 The thermometer is the only safe guide, and should be 

 regularly consulted, and whenever it indicates 75°, it is safe 

 to admit less or more of the outer air, proportioned of 

 course to the condition of the atmosphere ; if thei-e be 

 bright sunshine, and cold wind, very little will suffice; if 

 calm, mild, and sunny, admit larger quantities. 



Coverings for Protection against Frost. — To cover 

 up hot-bed sashes, we use either light pine shutters or 

 straw mats ; the shutters are made the exact size of the 

 sash ; there is no necessity of their being more than half 

 an inch in thickness, as that is quite as effective in keeping 

 out the cold as two inches would be, and they are much 

 cheaper and more convenient to handle. Straw Mats are, 



