Q and A #1
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Common Hydroponic Questions: Light, Nutrients, Trays & More
We’ve been getting a lot of great questions lately about hydroponics, so we’re kicking off a short Q&A series to help fellow growers. Here are six questions we got this past week, plus two questions we asked other growers to improve our own system.
1. How Much Artificial Light Do You Give Lettuce?
From September 11 to March 1, we give our lettuce eight hours of darkness each day. We only run artificial lights when the sun isn’t out. Outside that window, lighting depends on:
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Plant size
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Weather conditions
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Production needs
We use 300-watt lights on 12x12 spacing.
⚠️ Tip burn in bib lettuce under lights can indicate too much light or stress from fast growth outpacing nutrient uptake—similar to issues caused by low humidity.
2. How Do You Use Shade Cloth in the Greenhouse?
Our shade cloth helps us regulate temperature, not block light. We want maximum light year-round, especially in Wyoming.
Here's how we use our automatic system:
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At 75.5°F → close to 30%
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At 78.7°F → close to 60%
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At 81°F → almost fully closed (we leave a gap for air flow)
🌡️ This keeps temps under control without creating extreme heat above the cloth.
3. What Plug Tray Do You Use for Lettuce?
We use plug trays from Profile Products. They’re made of 100% peat, which is rare—many growers prefer a 50/50 mix with coco fiber. But this tray works great for our system.
4. Do You Use Liquid Fertilizers?
No—we stick with dry fertilizers. Liquid formulas often include a lot of water, which means you’re paying more for shipping and storage. Dry nutrients are more cost-effective and still deliver excellent results.
5. What State Are You In?
We grow in Wyoming. 🏔️
6. What Trays Do You Use for Arugula?
We use a 36-hole raft tray. This setup gives us the best yield per square foot per week for arugula.
Bonus: Drop Seeder Questions
We make a drop seeder that fits 1 ft. x 2 ft. trays. Most American 1020 trays will work. Some European trays may not.
✅ Custom trays? Yes—we do them! Just reach out.
🧠 What We're Learning: 2 Questions We Asked Other Growers
1. What’s the Difference Between Mobile and Immobile Nutrients?
This is key for diagnosing deficiencies:
Mobile nutrients (can move within the plant):
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Nitrogen (N)
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Phosphorus (P)
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Potassium (K)
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Magnesium (Mg)
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Molybdenum (Mo)
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Chlorine (Cl)
➡️ Deficiencies in these show up in older leaves first.
Immobile nutrients (stay fixed in older tissue):
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Calcium (Ca)
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Boron (B)
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Iron (Fe)
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Manganese (Mn)
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Copper (Cu)
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Zinc (Zn)
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Sulfur (S)
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Nickel (Ni)
➡️ Deficiencies in these appear in new growth first.
📌 Example: Yellowing in top leaves might indicate an iron deficiency (immobile). Yellowing in bottom leaves might point to a magnesium issue (mobile).
2. What Chloride Levels Are Safe in Hydro Water?
We asked a grower from AmHydro, and here’s what he said:
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Ideal chloride level: under 50 ppm
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Still okay: up to 75 ppm
There’s wiggle room, but staying under 50 is best.
📣 Got Questions?
Drop them in the comments or send them our way. We'll answer them in next week's Q&A!