September 12, 2021

Fall Garden: Planting By Length of Daylight

Several years ago, I blogged about what I had learned about soil temperature and plant growth ("What I'm Learning About Fall Gardening.") For awhile, I tried to plant my fall garden after the soil temperature dropped below 80°F (26.6°C). But for some reason, taking the soil's temperature everyday became extra chore that got lost in the huge pile of other things to do. The other day, I was reading Debby Riddle's blog Riddle Family Farm, and she mentioned the Persephone season. I had completely forgotten about that. I shouldn't have, because the concept is extremely useful for fall and winter gardeners.

The Persephone season is a concept that Eliot Coleman mentions in his books, The Winter Harvest Handbook and Four Season Harvest. The story of Persephone is a mythological explanation of why most plant life becomes dormant in winter. Technically known as solar winter, Eliot's observation is that plant growth pretty much ceases when daylight is less than ten hours in length. For fall planting, the recommendation is to get cold tolerant crops planted so that they are fairly well established by the time solar winter begins. A good estimate of that is approximately 75% of their days to maturity.

According to TimeAndDate.com's sunrise and sunset calculator for my location, 10-hour days begin November 30 for me. So, for example, if a seed packet lists 60 days to maturity, I'll calculate 75% of 60.

60 x 0.75 = 45

So I count back 45 days from Nov. 30 and plant my seed before that date. In this case, before October 16th.

I'm not discounting soil temperature, but have to say that for me and my lifestyle, having a set date really helps. My cooperative extension says to plant fall crops in August, but it's often so hot and dry in August, that planting just doesn't feel right. And I know from experience that if I wait until late October, I'm not planting a fall garden, I'm getting an early start on the following year's spring garden. Intuitively, September has always felt right, so working this out systematically has been very affirming.

This dovetails beautifully with my agrarian year. My winter months are December, January, and February, and I find it fascinating that solar winter for my location begins the last day of November. I love it when all the pieces fit so neatly together.

20 comments:

Boud said...

I agree about August planting. Never worked here. Also the extension says to plant turnips in July. Which results in spindly heat shriveled plants, no matter what they say.
I never heard of the Persephone idea, but it certainly makes sense to calculate that way.

SmartAlex said...

Here in zone 5b Western NY, I've found just about anything will be productive if I get it seeded (direct or transplant) before Aug 1st. And then transplanted items can go in whenever they are sized up enough. Now that we are into September I am dividing and relocating existing plants. Come October gardening season is over and frost is on the way. Right now I am SO MUCH enjoying the late bush beans I have growing. They aren't ready to pick just yet, but the plants are so fresh and gorgeous in this time of general decline that it does my heart good.

Leigh said...

Boud, I've never had any luck with July or August planted seed. At least directly sowed. If I can plant in trays and keep them watered, they have a chance.

Leigh said...

Alex, knowing your local and regional growing patterns is so important! It's fascinating how different our experiences can be, but exciting when someone figures it out and adapts. This explains why your blog is always such a treat to visit. :)

Goatldi said...

Absolutely brilliant! I too have had issues with planting as early as September which was as far as I would push it thinking it was late. Now I know it was way too early lol

Basically Leigh we are on the same timeline so I will apologize to my beets, beans and spinach that I threw in the ground too early. The kale does seem to be doing nicely but they’re in a different area from the rest that are struggling too warm!

To date everything you have reported from the agrarian calendar to this over the last year has convinced me once again that when you start messing with stuff and rearranging deck chairs to make it more convenient or faster or easier you’re in for nothing but trouble!

Leigh said...

Ha! I know I'm not smart enough to come up with a better arrangement of deck chairs, LOL. Nature was created with the perfect system already in place. Funny it takes us humans so long to figure that out. :

www.self-sufficientsam.blogspot.com said...

Very interesting! I have one of Elliott Coleman's books but I can't remember which one. I know I read it several times and it is not one that I would ever get rid even though my gardening days are waning. I just went out to find a horn worm invasion. I don't know how people garden here...so many critters and bugs and diseases. I never had any problems up North in all the years I gardened. I really respect anyone that can garden down here in the South! LOL!
Thank you for the calculations though....just in case I change my mind about gardening...lol!

Debby Riddle said...

I always enjoy your formulas. It's all about working with what we're given it seems. I buy lettuce starts when I can, and I buy twice what would normally feed us to account for the initial lack of regrowth when I harvest the outer leaves. In the Spring, there's an abundance, plenty to share.

Leigh said...

Debby, I absolutely agree with working with what we've got. That makes so much more sense than trying to create a system that relies heavily on constant inputs.

I've got lettuce planted for fall. I'll probably start a few in pots too. Getting really hungry for lettuce!

Leigh said...

Sam, gardening in the south is a challenge for sure! But Eliot Coleman has helped me understand how to have a productive fall and winter garden, which I really appreciate. :)

Ed said...

This is my first year to plant any fall crops so we just winged it. We planted green beans and thus far they seem to be doing great. It that turns out though, we will probably consider more things next year.

Gramma Connie said...

Very interesting post! I checked the link and found that our solar winter (Phoenix) begins a week into Dec. Since I live in the city at a new home with a small planting space, I have noticed that at one point during winter my garden only received 6 hours of direct sun. We had 10 plus hours of sun light but my house and the back fence shaded all but 6 hours. I'm curious how that changes things. I think I will start keeping notes.

Leigh said...

Ed, winging it is a great way to experiment. Plus make some important observations. I hope your fall garden thrives!

Leigh said...

Gramma Connie, good observations! I'll be curious about what you learn!

Toirdhealbheach Beucail said...

Leigh, that makes a lot of sense (as - from what I have read - things like peppers and tomatoes will stop setting fruit above 90 F, which explains why I have such poor yields). Experientially, in Old Home things needed to be in the ground by the end of October; here in New Home it can nudge a bit into November, but not much.

I do like a hard number like 10 hours though. Gives an easy target to manage.

Leigh said...

TB, I've concluded the same thing, that it's easier to work with a specific number and date. Like you, I've figured out some general guidelines for myself. One of them is that the temps usually start to cool in September, so that really seems like my month to plant. Busy doing that now. :)

Michelle said...

Interesting! I just calculated this for me, and to have 45 days of more than 10-hour days, I would have had to plant . . . yesterday! I may dig out some carrot seeds I have on hand and plant them today, just to see what they do. Usually my garden is so weedy by the end of the summer I give up, but we've been so dry and I've only done soaker hose and drip watering, so the weeds are minimal.

Leigh said...

Michelle, experiment! :)

Nina said...

Sadly, I couldn't get the calculations to fit with what I know for frost dates etc. I don't even worry much about fall gardens. I plant some lettuce in July for late summer, fall harvests and the chard really does come into it's own in September. Our growing season is really just too short for late plantings of other things. Our tomatoes don't even start to ripen until mid-August. One of the quirks of our area is that we all know our autumn starts after Labour Day weekend, instead of the autumnal equinox!

Leigh said...

Nina, observing and understanding your own local growing conditions is so important! My frost dates are so unpredictable (anywhere from mid-October to mid-December), that I've learned to pretty much disregard them altogether. I also know that every fall garden is a risk. Some winters are mild enough to get a harvest all season long, some are too cold, and everything goes dormant. I feel fortunate to even be able to try.