Soil Temperature Data - When to Plant

May 17, 2011

I came across this while perusing the internet with my google machine:

Soil temperature data for the last 7 days is available at http://landslides.usgs.gov/monitoring/portland/rtd/temperature.php

Over the last 7 days, the soil temperature has risen to 5 Celsius, or about 41 degrees f. Why do we care? Well, because "How to Grow More Vegetables" provides a table of the desired soil temperatures for seed germination for each vegetable.  A few excerpts from the vegetables that you would typically sow from seed in your garden:

peas    40F (min)   40F-75F (optimal)
carrot  40F (min)   45F-85F (optimal)
onion   35F (min)   50F-95F (optimal)
lettuce 35F (min)   50F-95F (optimal)

Likewise, there are appropriate temperature ranges for optimal GROWING. Yesterday, the annual average temps are: (from wunderground.com)

May 17, 2011	Max Temp	Min Temp
Normal (KTTD)	69 °F	47 °F
Record (KTTD)	92 °F (2008)	36 °F (1996)
Yesterday	62 °F	42 °F

Here are a few optimal growing temperature ranges :


tomatoes   65F-85F (70F-75F optimal)
onions       45F-85F (55F-75F optimal)
potatoes carrots celery lettuce parsley peas  45F-75F (60F-65F optimal)


Grow on!!