But dryback alone won't get you there
Here's what most growers miss. Dryback helps you steer the vegetative–generative balance, true. But on its own, it's not enough to fine-tune the crop.
The reason is simple: you can hit the exact same dryback in completely different ways, and the plant reacts differently to each one.
Say you reach your target by finishing irrigation earlier in the evening and starting earlier in the morning. The number looks right. But if you start watering too soon after sunrise, you've made a mistake the dryback figure won't show you. The plant only wakes up when the sun brings light and energy. Water it before that, and you've fed a crop that wasn't ready to work yet. The result is soft, lazy, vegetative growth.
Let's look at it in real data
On the chart we've marked the dryback. Let's say it's 12%. To reach that target, we have two windows we can adjust:
(1) From the last irrigation to sunset.
(2) From sunrise to the first irrigation.
And here's the key insight. You can hit that same 12% by shortening window (2), the gap between sunrise and your first irrigation. That means watering early, while the plant is still basically asleep.
The first irrigation of the day matters far more than the dryback number itself. Our data shows it has the single biggest effect on how the plant performs all day. Start too early and you might still hit your target on paper, but the plant gets water before it's ready. It turns lazy. It stops investing energy into its roots. And you drift toward a vegetative result.
Even when the dryback sits in neutral territory, somewhere between 8% and 12%, neither strongly generative nor vegetative, starting too early still pushes the crop the vegetative way. The plant gets its water, the growing tip turns fat, and that has a strong knock-on effect on flowering and pollen development.
Everyone focuses on the dryback. Everyone knows that number. But the real lever is this: match the timing of your first irrigation to your strategy. No other tool lets you read your morning dryback this precisely, and that's exactly where our 5-second data frequency earns its keep. It's what makes Trutina able to show you this.
We've analysed over 216 billion data points, and the conclusion is clear: getting the timing of that first irrigation right has an enormous effect on the whole day's performance. Get the start wrong, and no matter how much you optimise later, you'll never climb back to the day's full potential.
Transpiration is the cost, not the goal
Here's a myth worth retiring: "more transpiration means more growth."
In reality, of all the water a plant takes up, around 98% leaves again as transpiration. Only about 2% actually becomes new biomass.
So transpiration isn't the prize. It's the price the plant pays to get there. It opens its stomata to take in CO₂, and loses water as the unavoidable cost. Chase transpiration for its own sake and all you're really doing is spending water.
The real question isn't "how much is the plant transpiring?" It's "how efficiently is it turning that water into growth?" That's water-use efficiency, and that's where we go next week.
