…and What Growers Can Do Differently Next Season
If you grow onions or garlic in the Central Valley, you probably don’t need us to tell you it was a rough year. Bulbs sized up smaller than usual. Some fields tipped over well before they should have. And as the harvest numbers come in, a lot of growers are looking at yields well under what they pulled last year, some garlic below 7 tons per acre.
It’s tempting to chalk that up to “just a tough season.” But when our agronomy team walked the fields this spring and summer, a clear pattern emerged.
What Actually Happened
Two things converged this year, and the combination made the damage worse than either would have caused alone.
The first was heat. March brought exceptional temperatures that pushed evapotranspiration rates well above what onions and garlic typically deal with at that point in the season — the plants were losing water faster than normal, putting stress on the crops.
The second, and more consequential, factor was water. A lot of growers had no choice but to switch from surface water to well water partway through the season, and Central Valley well water tends to carry a lot more salt. Our agronomists saw the telltale sign of that switch across the region: necrotic leaf tips showing up right around the time fields changed water sources.
That combination — heat stress plus salty water — created what’s really a double problem. Salt makes it physically harder for a plant to take up water in the first place. And the sodium riding along with that water competes directly with potassium for uptake at the root.
Why Potassium is the Real Loser
Sodium and potassium behave similarly enough that plants will take up whichever is more available, but they are not interchangeable once they’re inside the plant. Sodium doesn’t help a plant move sugars the way potassium does, and it’s a poor substitute when it comes to keeping cell walls strong. For a bulb crop, that shows up in a very specific, very visible way: the neck weakens prematurely and the plant tips over before it’s finished sizing. Once that happens, the plant is physiologically done; whatever bulb size it had at that point is close to what ends up in the bin.
It compounds from there. High sodium alongside high potassium in the soil also tends to reduce uptake and utilization of manganese and copper — two micronutrients that matter for the same thing, stalk strength and elasticity. So the fields hit hardest this year weren’t dealing with one problem. They were dealing with a chain reaction that started with a water source switch and ended with bulbs that stopped sizing early.
The fields that didn’t have to lean as hard on well water told a different story. Better water uptake, better potassium assimilation, better bulb size and density. Same weather conditions and inputs, but different water led to a different outcome.
What This Means for Next Year’s Planting
Harvest for this season is already underway, which means growers are making decisions about next year’s program right now, and this is exactly the kind of problem that’s preventable with the right approach to nutrition.
The core issue this year wasn’t too little water or even too little fertilizer. Onions and garlic are shallow-rooted crops that need frequent, consistent irrigation to begin with, which makes them a strong match for a different approach: continuous fertigation where nutrients, especially potassium, are delivered with every irrigation cycle instead of in a handful of heavy doses.
That’s the idea behind Deerpoint’s DPG White Box™ system. A few specifics heading into next season’s planning:
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Continuous potassium delivery competes with sodium in real time. Instead of hoping a big application early in the season still has potassium available in the root zone when a well switch hits, continuous fertigation keeps K available every single irrigation so the plant can keep competing for uptake instead of losing that fight mid-season.
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Nitrogen efficiency, without sacrificing yield. In fields Deerpoint manages, growers have brought nitrogen programs down from the 200-unit range to under 100 units with no drop in yield. Small, continuous doses simply outperform periodic heavy feeding for a shallow-rooted crop.
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Winter doesn’t have to be a blind spot. Onions and garlic are winter crops, which means the nutrition program has to survive the rainy season, and most growers just shut fertigation off when they’re not irrigating for water. Deerpoint’s field technicians manage short winter irrigation runs specifically to keep nutrients available in the root zone through the wet months, so that piece isn’t left to chance.
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It’s a managed system, not a product you have to babysit. The DPG White Box™, installation, an assigned field technician, and tissue/soil/water testing all season are included — growers approve the program, Deerpoint’s team executes and adjusts it.
The Window is Now
Planting decisions for the next season start now, and whatever program is in place by then is what the crop runs on all winter. If this year’s tipping, small bulbs, or lower tonnage sound familiar, it’s worth a conversation before that window closes, not after next year’s harvest tells the same story.
Get a free on-site evaluation for your allium fields. https://deerpointgroup.com/request-a-consultation/