Substrate EC Mistakes Most Growers Still Make

Join Tyler Simmons, Technical Expert at Front Row Ag—a fertilizer brand specialized for cultivators—as he dives deep into substrate EC management, lighting strategies, and optimizing plant performance. In this interview hosted by FOHSE, Tyler explains how to maintain optimal EC levels, avoid deficiencies, and maximize plant growth through proper irrigation, lighting, and nutrient strategies. From veg to flower, you'll learn actionable tips to take your cultivation techniques to the next level.

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Chapters:
0:00 Introduction & Key Factors of Substrate EC
0:34 Understanding Peak, Daytime Low, and Active EC Levels
1:49 The Impact of Low Substrate EC on Plant Health
2:28 Charging the Substrate for Vegging Plants
3:50 High EC Strategies During Stretch Periods
4:51 Adjusting EC Levels for the Bulking Phase of Flower
5:15 High-Intensity Lighting and Challenges with Finishing Strains
5:30 Generative Signals and Peak ECs in Ripening Plants
5:53 The Kitchen Sink Strategy for Long-Flowering Cultivars
6:16 Helping Growers Understand Plant Cues and Maximizing LED Lighting

Transcript:

When we talk substrate EC, we’re really talking about several ECs across the day—and mixing them up causes bad targets. There’s the peak EC (usually right before first irrigation, when WC is lowest), the daytime low EC (after you’ve generated runoff at the end of P1), and the active EC the plant experiences during the main transpiration hours. That last one is the most important—what the plant “feels” while it’s working.

Baselines that prevent problems: if your sensor data (e.g., Teros-12–style readings) show substrate EC < 3.0, expect imminent issues—deficiencies, slowed growth, poor vigor. Rule #1: don’t let substrate EC drop below 3.0 during the day.

Charging for veg (coco or rockwool): start strong so you can run higher light. Charge at ~3.3–3.5 EC, then plant directly into that. With that fertility you can start around 350–400 PPFD and ramp to ~600+ over a few days to a week. In 10–14 days you’ll have a stout, fast plant; if you charge low (e.g., ~2.2 EC), the same size takes roughly twice as long and you’ll need a slow, fragile acclimation.

Flower strategy: during stretch, run a higher EC (often ~5–8) to steer osmotic/matric signals. In mid/bulk, drop EC (commonly ~3–5 or 4–6, cultivar and light dependent). Late in flower—especially under high PPFD—some cultivars “don’t want to finish,” so you stack cues: adjust spectrum/distribution, switch to a ripening formula, use substrate cues (allow higher peaks but lower daytime lows via runoff/drybacks), and coordinate light, CO₂, day/night temps, irrigation—the “kitchen sink” approach—to push timely ripening.

LED note: modern LEDs let you push intensity beyond where legacy heat would have stopped you; just be sure EC and irrigation strategy keep pace so the plant is never underfed during peak transpiration.