Growing Degree Days/Units

Dan in Ct 1/25/2019, 9:31 am

Growing Degree Days came from the study of growing corn and has been adopted by Phenology to explain why we plant things when certain natural phenomenon happen. Because of this are there any here who measure soil temperature before planting or transplanting rather than looking at a date on the calendar and having at it? If I can get my garden secretary to keep better notes, I plan on taking soil measurements in both my buckets and raised beds. Note to self, put inexpensive mailbox somewhere in garden area to hold pencils and notebook. Possibly put a spare beer in it for secretary.

OhioGardener 1/25/2019, 11:23 am

Dan in Ct wrote: Because of this are there any here who measure soil temperature before planting or transplanting rather than looking at a date on the calendar and having at it?

Yes, I am one such person.

As Dr. Jerry Parson's said: "More important than moon signs and more predictable than weather is another variable which drastically affects how seeds and transplants grow - soil temperature. Soil temperature is a factor which few of us consider important enough to check before planting yet it is probably the most important factor affecting seed germination, stand establishment and seedling growth."

SQWIB 1/25/2019, 11:25 am

OhioGardener wrote:
Dan in Ct wrote: Because of this are there any here who measure soil temperature before planting or transplanting rather than looking at a date on the calendar and having at it?

Yes, I am one such person.

As Dr. Jerry Parson's said: "More important than moon signs and more predictable than weather is another variable which drastically affects how seeds and transplants grow - soil temperature. Soil temperature is a factor which few of us consider important enough to check before planting yet it is probably the most important factor affecting seed germination, stand establishment and seedling growth."

I think I am going to plant based on soil temperature this year, along with a good 10 day forecast.
Thanks for sharing this.

OhioGardener 1/25/2019, 11:33 am

The chart above indicates the minimum and maximum germination temperature ranges for each vegetable crop. The location of the black dot indicates the optimum germination temperatures (according to the University of California at Davis). The green dot is the "realistic" soil temperatures that Dr. Parsons recommends to ensure good germination in the garden. For practical purposes, you can start planting as soon as the soil reaches this temperature.

Dr. Jerry Parsons on Soil Temp Planting

SQWIB 1/25/2019, 2:19 pm

OhioGardener wrote:

The chart above indicates the minimum and maximum germination temperature ranges for each vegetable crop. The location of the black dot indicates the optimum germination temperatures (according to the University of California at Davis). The green dot is the "realistic" soil temperatures that Dr. Parsons recommends to ensure good germination in the garden. For practical purposes, you can start planting as soon as the soil reaches this temperature.

Dr. Jerry Parsons on Soil Temp Planting

That is awesome, going to print out a copy.

"green dot is the "realistic" soil temperatures that Dr. Parsons recommends to ensure good germination"

I think you mean "Planting".

Thanks for the awesome chart

**donnainzone5** 1/25/2019, 2:57 pm

Yes, last year I started using soil temps as one of the differing phenomena to consider when planting. Of course, with our short growing season here in Central Oregon, I'm considering starting more varieties from seed indoors to give them a head start.

yolos 1/25/2019, 6:15 pm

I first find the general planting date suggested for my area. Then I decide whether I want to try to plant earlier using some kind of season extension method. Then before that time, I look at the long range forecast and start taking soil temps. I may even try to raise the soil temps by different methods. I am going to try to raise soil temps this year to plant my potatoes so they can become full grown before the heat kills them off. Or I plant inside and then transfer outside shortly after germination. I have done a combination of these methods (with excellent success) to plant corn 2 to 4 weeks earlier than normal.

**sanderson** 1/26/2019, 4:03 am

I have checked the temps of the Mel's Mix when sowing or transplanting starts of melon, cucumber and squash seeds, primarily to prevent dampening-off.

Dan in Ct 1/26/2019, 9:29 am

Growing Degree Days can also be used to put a gardener on the lookout for specific insects and can help to eliminate them before they become an infestation. Here is a link to Insect Emergence based on Growing Degree Days. It covers a wide variety of insect species but the link is to University of New Hampshire extension, so it is probably more for east coast gardeners but begs the question do west coast relative have similar amount of GDDs for emergence.

http://ccetompkins.org/resources/using-growing-degree-days-for-insect-management

**sanderson** 1/30/2019, 2:46 am

California: http://ipm.ucanr.edu/WEATHER/index.html

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