Greetings and a question...

[ezzirah]

Hello from Zone 7A!

I am new to the board and I look forward to many wonderful garden adventures with everyone!

I do have one question, and that is now that it is time to put in the fall garden why do we not pay much more attention to soil temperature? I know in the spring it is all about the soil temperature, but it seems like the fall it is all about the calendar when determining when to plant, why is that? I ask this because here in Oklahoma it has been blazing hot and extremely dry. I am worried that if I direct seed anything in this it will just die. I have started a number of seeds inside (too hot even in the shade!) and will harden them off and transplant, but I wanted to direct seed my turnips....


Thanks!

 

[digitS']

Welcome to TEG, ezzirah !

I think you make an excellent point. Soil temperature is important and I try to have some idea about what the seeds are experiencing in the spring.

Here is a table with temperatures and days to germination from the University of Minnesota. You can see that sowing beet seed in the spring, for example, when the soil is only 41F makes almost no sense because it will take 6 weeks to germinate. Of course, after a month the soil temperature may well be above 50. You may as well wait since emergence will be at the same time and the risk of seed rotting in the ground is lower the less time it sits in the soil.

The late garden is a different story. One danger is that the seed will germinate but the seedling will quickly die because of a lack of soil moisture. Since it takes only a few hours for the surface to dry under a blazing hot sun, seed that is sown only a 1/4 inch down may have a real tough time of it!

I don't think that it would surprise anyone if 1/4 inch into the soil that it would be above 95 on a day with air temperature is above 90. Lettuce seed can't even make a start.

Between dry surface soil and high temps, only things like bean seed has a reasonable chance of germinating during the hot days of summer. Still, some things like lettuce, spinach and brassicas like turnips and bok choy do fairly well growing during the cooler temperatures of fall. It becomes a "timing game" to plant them at the right moment when the seed can germinate and the plants can still have enuf time to make some growth before frost.

Steve

 

[boggybranch]

VERY good link, Steve......Thanks


Welcome aboard, ez.

 

[ezzirah]

Thank you for the link! I bookmarked it for sure. I never understood why they use dates for the fall and not soil temperature. It seems to me the easier thing to control would be the air temperature, with things like low tunnels and row covers, etc. Than the soil temperature that one really has zero control over. Yeah, there is shade cloth, but that would only go so far when the outside temp. is in the 100's, I would think.