Visualize!
This year I planted nine short-season/cold tolerant tomato plants, three each of Glacier, Fourth of July, and Stiletz. These varieties tolerate cool nights and so can be set out in the garden about a month earlier than most tomato varieties. They produce ripe fruit quickly, with two of the three advertising less than 60 days to maturity.
That combination gives you the promise of having some ripe tomatoes quite early in the year. And this year, I am pleased to report that this promise has been fulfilled. I ate my first ripe tomato out of the garden today. And it’s not even officially summer yet.
I think that’s pretty good for gardening in Zone 7 without a greenhouse.
So, how did that first ripe tomato taste? Eh, pretty much like a tomato. Not bad, but nothing to write home about, either. I’m sure that in the days before decent grocery-store tomatoes became available, I’d have thought it a miracle on a vine. But now, with (e.g.) Campari tomatoes available year-round, that first fresh tomato was nice, but nothing you couldn’t buy at Safeway.
Above: A couple of ripe Glacier tomatoes, the winners in this year’s short-season tomato race, 6/20/2022.
Above: Some almost-ripe Fourth of July tomatoes, on 6/20/2022. These came in second, but they are clearly going to live up to their name.
For Mature Audiences Only
Now that I have have my first ripe tomato, with the promise of more to follow, I can finally address a question that has been nagging me ever since I decided to try this.
What does “days to maturity” actually mean? From what starting point, to what end point, under what conditions? I’ve seen this on seed packets all my life. I’ve never been quite sure what it means.
Let me use these two short-season tomato varieties to illustrate the issue. I planted these in the garden on 4/10/2022. I started them from seed about a month earlier. Here’s how the actual days to first ripe fruit compare to the “days to maturity” on the seed packets:
As you can see above, in this case the actual elapsed time between sowing the seeds and the first mature fruit was about twice the stated “days to maturity”.
Is that typical? I can’t even ask that question until I figure out what seed sellers mean by “days to maturity”.
As with so much of home gardening, I see a lot of folklore and wrong answers along with the correct information. But even with that, and putting aside all the variations that might arise due to the weather, the soil, the length of the day, and so on, I believe that there is literally no standard definition of what “days to maturity” actually measures.
So, at the end of the day, its no wonder that I don’t know what it means. It’s not really a well-defined term.
Let me now summarize, as best I can, kind of the gist of what it is supposed to mean. This is based mainly on the information found in these three sources:
- A detailed discussion of the entire “days to maturity” issue on a blog titled Garden Betty.
- A more compact explanation on The Spruce Eats.
- Oregon State University extension service.
For plants that are traditionally started indoors, in pots, then transplanted to the garden, days to maturity is defined as the number of days between:
- the time that a seedling that is ready to be transplanted is put into the ground, and
- the time the first fruit is ripe enough to be picked for eating,
- under optimal conditions (temperature, day length, water, fertilizer).
For plants that are traditional directly sown into the soil, days to maturity is defined as the number of days between:
- the time you plant the seed …
- or maybe the time the planted seed sprouts …
- or maybe the time the sprouted seed shows its first true leaves, and
- the time the first fruit is ripe enough to be picked for eating,
- under optimal conditions (temperature, day length, water, fertilizer).
No matter how you slice it, there’s a ton of ambiguity in those definitions. At what point is a seedling ready to be transplanted? What does ripe mean (e.g., for cucumbers that can be used either small, as pickling cukes, or larger, as slicers). Does the clock start when you plant the seed, or a couple of weeks later when you see the first true leaves?
On top of that, planting at the times where this figure really matters — early spring or late fall — guarantees that you won’t have optimal growing conditions. There’s a nice discussion of this point in the Garden Betty blog cited above. So, these figures will be the least reliable just when you’ll be counting on them the most..
Finally, it almost goes without saying that different seed vendors are going to define and measure “days to maturity” differently. So while “days to maturity” might give you some general guidelines as to what will ripen first, within a given seed vendor, you probably can’t compare them across vendors. Likely this explains why my actual observed days to maturity above, under identical growing conditions, are in the reverse order of the vendor-stated days to maturity. Plausibly one vendor uses a more aggressive definition than the other.
A practical takeaway from a novice gardener
I get the fact that YMMV. I did not expect to see mature fruit appear exactly “days to maturity” after I set out my plants.
What I didn’t understand — before focusing on this — is that your mileage may vary a lot. When you see a “days to maturity” number, you can’t reliable expect to see ripe in that time, plus or minus a few days. Instead, I’m guessing that there’s never a “minus” — that those day counts are under absolutely ideal conditions. And then, you can’t be surprised if the actual day count is several weeks longer than the days to maturity figure, even if you’ve started the seeds weeks before you planted the seedlings in the ground (and thereby started the “days to maturity” clock).
This explains, I think, why I totally failed to grow summer squash last fall, after the squash vine borer (SVB) left for the year. Planting a late-season crop is a commonly-mentioned strategy for avoiding the SVB. So, after I observed my last SVB last year, I put a few summer squash seeds into the ground. I had far more than 60 days of growing season left, which is the approximate “days to maturity” of the varieties I was growing. But I got no squash.
Let me do the math, in light of this new-found knowledge. Typical first frost date in this area is October 15. Stated days to maturity is 60. But in that cooler, short-day climate, I can count on it being at least 90. But that’s measured from the time you have a pot-grown plant that is ready to be transplanted into the garden. So chuck on another 30 days to raise the seedling from seed to “ready to transplant”. But that’s from the time the very first squash appears. So add at least another 21 days if you want to get a mere three weeks of actual production out of those squash plants. Now add that up. And, of course, put it all in a spreadsheet.
The upshot is that for a fall crop of summer squash: a) I should have planted the seeds weeks ago, but more importantly, b) I can’t actually grow a fall crop of summer squash, out in the open, in this climate, that avoids the SVB. I’d have to set the plants out in the garden squarely in the middle of SVB season.
The bottom line is that if I want a fall crop of summer squash, without pesticides, I’m going to have to start out by growing my squash seedlings under insect-proof netting. Which is exactly what I’m doing with my parthenocarpic varieties now. The only difference is that I’d be able to take that netting off after the first six weeks in the garden.
It’s possible that I’ve overstated the fudge-factor here, given that I’d have to start these in the garden pretty much at the start of summer anyway. But even if I completely removed that 30-day fudge factor, I’d still have to put these plants in the garden weeks before the typical end of SVB season.
The ultimate takeaway here is that if you use “days to maturity” for estimating the last viable planting date for a fall crop, you need to add a lot to the raw number. You need to add in the minimum number of days over which you’d like the plants to be productive. You need to add a fudge factor for what are likely to be sub-optimal growing conditions. And then, for plants traditionally started indoors, you need to add in the time to produce your garden-ready seedling from the seed.
And when I do that, for summer squash and Zone 7, it turns out that I can’t dodge the squash vine borer by aiming for a fall crop of summer squash. If you don’t want to use pesticides, the only thing the fall crop gives you is the ability to remove the insect netting from the squash some weeks before the plant is due to begin setting fruit.
