Can I keep frost off of potato tops by building smudge fires! I would like to plant about February 1, but we usually have a few light frosts here during March. If I were to turn water in the field when too cold, would that keep the frost off, and if so, would I have to turn water down each row, or would one furrow full of water to about every fourth or sixth row be enough? You can prevent frost by smudging for potatoes just as you can for other vegetables. The potato, however, needs little protection of this kind and will endure a light frost which would be destructive to tomatoes, melons, and other more tender growths. Unless you have a very frosty situation, you can certainly grow potatoes without frost protection, and they should be planted earlier than February first if the ground is in good condition. The great secret of success in growing potatoes in southern California is to get a good early start before the heat and drought come on. Water will protect from frost if the temperature only goes to about 28 degrees and does not stay there too long. The more water there is exposed the longer may be the protection, but probably not against a lower temperature. Growing Sweet Potato Plants. How shall I make a hot-bed to raise sweet potato plants? I don't mean to put glass over bed, but want full description of an up-to-date outfit for raising them. Manure hot-beds have been largely abandoned for growing sweet potato slips, though, of course, you can grow them that way on a small scale or for experiment. In the large sweet potato districts, elaborate arrangements for bottom heat by circulation of hot water or steam are in use. In a smaller way hot air works well. The Arizona Experiment Station tells how a very good sweet potato hot-bed at little cost is constructed as follows: A frame of rough boards seven feet wide, twenty feet long and fourteen inches deep is laid down over two flues made by digging two trenches one foot deep and about two feet wide, lengthwise of the bed. These trenches are covered with plank or iron roofing, and are equipped with a fire pit at one end and short smokestack at the other. Four inches of soil is filled into this bed and sweet potatoes placed upon it in a layer which is then covered with two or three inches more of soil. Large potatoes may be split and laid flat side down. The whole bed is then covered with muslin, operating on a roller by which to cover and uncover the bed. Thus prepared, the bed may easily be kept at a temperature of 60 to 70 degrees F. by smouldering wood fires in the fire boxes. The potatoes, kept moist at this temperature, sprout promptly and will be ready to transplant in about six weeks. A bed of the size mentioned will receive five to seven bushels of seed roots, which will make slips enough to plant an acre or more of potatoes. Growing Sweet Potatoes.