How Does Your Garden Grow?
One measure of how well garden crops will grow is the range of temperature each day. Many Alaskan crops, such as peas, oats and potatoes, will have growth only if the temperature is above about 40°F (4°C). Others, sweet corn, beans and tomatoes, grow only if the temperature is above about 50°F (10°C). Up to a limit (in the high 80's), the growth is greater the warmer the day.
A growth index called the "growing-degree unit" has been compiled for several Alaskan locations. To obtain the index value for each day, the Fahrenheit maximum and minimum temperatures are added together and the sum is divided by two. This gives a sort of average temperature for the day. From this average temperature, one subtracts 40°, the temperature at which most Alaskan crops start to grow. Added up over the course of the summer, the total growing-degree units so obtained is a good indicator of agricultural potential.
Some surprises come out of the calculations of growing-degree unit totals. The famed Matanuska area (1763 units) ranks only third behind Big Delta (1791 units) and Fairbanks (1852 units), but it does handily beat out Homer (1274), Kasilof (1433) and Kodiak (1572). Because of its warm summers and long days, the Fort Yukon area has even more growing potential than the Fairbanks area.
These results would seem to prove that the farther north you live, the better will be your garden. Residents of Point Barrow and Barter Island may not believe the proof and might be inclined to point out that having continental climate helps a lot.
Actual tests with crops do support the indication of the growing-degree calculations. Dr. James Drew, head of the University's Institute of Agricultural Sciences, cites sweet corn as an example. He says that, aided by ground-warming mulches, sweet corn will not mature at Homer. With mulch, it will mature about one year in three at Matanuska, and it will every year at Fairbanks. At Fort Yukon, north of the Arctic Circle, sweet corn needs no help at all to mature every year.
