Best EC for cannabis

Adam Parsons

Cannabis Journalist & Staff Writer at Zamnesia

Adam Parsons

Last updated: October 16, 2025

Feeding your plants the proper nutrients starts with the right EC. Get it wrong and you could be starving or overfeeding your cannabis. In this guide, we'll explain what EC and PPM for cannabis mean and why they're the best tools for tracking nutrient strength.

You'll discover the ideal EC for cannabis at every growth stage, from fragile seedlings to heavy-yielding flowering plants, with easy-to-read EC and PPM charts for soil, coco, and hydroponics. We'll also show you how to measure and adjust EC levels using simple tools. You'll also discover troubleshooting tips to help you spot and fix common EC problems like overfeeding and underfeeding before they damage your crop.

What is EC and why does it matter?

EC (electrical conductivity) is a measurement of how well your water can conduct electricity, which directly relates to the amount of dissolved salts (nutrients) it contains. In cannabis cultivation, EC tells you how “strong” your nutrient solution is. The higher the EC, the more minerals are present; the lower the EC, the weaker the solution.

Closely linked to EC is PPM (parts per million). This measurement expresses the exact concentration of nutrients in your water, but essentially, it's another way of describing the same thing. Because meters often display EC or PPM, understanding both terms helps growers make sense of feeding schedules and nutrient charts.

Why does it matter? Cannabis plants absorb nutrients dissolved in water through their roots. If EC is too low, your plants may not get enough food, leading to pale leaves and slow growth. If EC is too high, roots can become overwhelmed, causing nutrient burn, curling leaves, or even nutrient lockout. Maintaining the right EC ensures your plants can take up nutrients efficiently, helping them thrive from seedling to harvest. For more information on watering and the nutrient requirements for cannabis plants, check out our extensive hub.

EC vs PPM: What's the difference?

While EC and PPM are closely related, they're not identical. As mentioned, EC measures the conductivity of the water directly, while PPM translates that conductivity into a number that represents the nutrient concentration. The challenge is that different meters and regions use different conversion factors:

• 500 scale (USA): 1.0 EC = 500 PPM
• 700 scale (Europe/UK): 1.0 EC = 700 PPM

This means two growers could measure the same solution and get different PPM readings, depending on their meters. Many experienced growers prefer to stick with EC for cannabis since it's a universal measurement.

Whether you're using an EC or PPM meter, regular calibration is essential for accurate readings. A small error in measurement can quickly lead to overfeeding or deficiencies, so always double-check your tools before adjusting your nutrient mix.

Ideal EC ranges for each growth stage

Cannabis plants have different nutrient needs as they develop, which means the ideal EC for cannabis changes depending on whether you're tending seedlings, in the vegetative stage, or in the middle of flowering. Keeping within the right range ensures strong growth and avoids underfeeding or nutrient burn.

Germination/seedling stage

At this stage, cannabis seedlings are incredibly delicate. Their roots can only handle a small amount of dissolved minerals, so the EC should remain very low, typically between 0.4–0.8 EC (200–400 PPM based on the US 500 scale). Many growers use plain, pH-balanced water until the first true leaves appear. Pushing nutrient strength too early can easily burn tender roots and slow down development.

Vegetative stage

During veg, plants build the foundation for a healthy yield by developing strong stems and lush foliage. This growth requires more nitrogen and minerals, so the EC for cannabis in veg is usually between 1.2–1.6 EC (600–800 PPM), depending on the medium (soil, coco, or hydro). Monitoring EC closely at this stage prevents deficiencies that could stunt growth or cause pale leaves.

Flowering stage

Once the light cycle changes and flowering begins, nutrient demands increase again. Plants need more phosphorus and potassium to support bud formation. The ideal EC range during flowering is typically 1.6–2.0 EC (800–1,000 PPM), with the upper end often used in the later weeks when buds are swelling. Tracking levels carefully helps growers avoid dreaded nutrient lockout, while ensuring maximum resin and flower development.

Flush period

In the final 1–2 weeks before harvest, most growers perform a flush by reducing or eliminating added nutrients. This helps remove excess salts and produces cleaner-tasting buds. EC should gradually drop to 0.4–0.6 EC (200–300 PPM), or close to that of your base water. A proper flush ensures the plant uses up stored nutrients, improving the smoothness and flavor of the final product.

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How to measure EC

Keeping your nutrient solution in the right range starts with accurate measurements. Luckily, modern tools make it quick and straightforward for home growers to check EC for cannabis in soil, coco, and hydroponic setups.

Tools

The most common way to measure nutrient strength is with an EC meter. These handheld devices give instant readings when dipped into water or a nutrient mix. For added convenience, many growers use combo meters, which measure EC, PPM, and pH simultaneously.

No matter which you choose, accuracy depends on regular calibration. Most meters come with calibration fluid. You can reset the device by checking against a known solution to ensure it's reading correctly. This is essential because even a slight drift in accuracy could lead you to add far too many or too few nutrients.

How to measure EC in soil

Measuring EC in soil is slightly trickier than in hydro, because nutrients interact with the organic matter in the medium. The most reliable method is to test runoff after watering:

1. Mix your nutrient solution as normal.
2. Water your plants until about 10–20% of the liquid drains out of the bottom of the pot.
3. Collect this runoff and measure the EC with your meter.

The result tells you how concentrated the nutrient solution is inside the root zone. If the runoff EC is much higher than what you put in, salts may be building up in the soil, which can often lead to nutrient lockout.

How to measure EC in hydroponics

Measuring EC in hydro systems is simpler because nutrients are dissolved directly in water. Just dip your EC meter into the reservoir or nutrient tank and take a reading. Many hydroponic growers also monitor the drain-to-waste runoff to see how much the plants are actually consuming.

By comparing the EC of your input solution (what you feed the plants) with the output solution (the runoff), you can quickly identify whether your cannabis is being overfed or underfed. If the runoff EC is consistently higher, salts are accumulating, and you may need to dilute the feed or flush the system.

Adjusting EC levels

Getting accurate readings is only half the job. Knowing how to adjust EC levels is what keeps your plants thriving. Depending on whether your readings are too high or too low, you'll need to dilute the solution or increase its strength.

Lowering EC

If your EC readings are too high, it means the nutrient concentration is stronger than your plants can handle. This can quickly lead to nutrient burn or even lockout. The simplest fix is dilution:

• Add plain pH-balanced water to your nutrient mix until the EC falls within the target range.
• Check the runoff EC if you're growing in soil or coco; salts may have built up in the medium if it's still too high.

In that case, a flush may be necessary. Flushing involves watering heavily with plain water (or a flushing solution) until the excess salts are washed out, bringing the EC back down to a safe level.

Raising EC

If your EC is consistently below the target range, your plants may not get enough food. Signs include pale leaves, slow growth, or weak stems. To raise EC:

• Increase the concentration of your nutrient solution by adding more base nutrients or supplements.
• Do this gradually, as a sudden jump in EC can shock your plants.

Always mix thoroughly, measure again, and feed slowly to avoid overshooting the correct level.

Avoiding EC spikes

EC can sometimes fluctuate suddenly, especially in hydro systems where nutrients concentrate as water evaporates. To prevent dangerous spikes:

• Top up reservoirs regularly with fresh water.
• Stir or circulate nutrient solutions to keep salts evenly distributed.
• Monitor daily, especially during hot or dry conditions with higher evaporation rates.

By monitoring closely and making small adjustments, you can maintain a stable feeding environment that supports steady, healthy growth.

Common EC problems and how to fix them

Even experienced growers sometimes struggle with keeping EC for cannabis in the right range. If left unchecked, incorrect nutrient levels can cause stress, nutrient deficiencies, or poor yields. By learning to recognize the signs early, you can quickly restore balance to your grow. For more information on nutrients for your cannabis, take a look at our extensive guide.

Signs of overfeeding

When EC is too high, plants receive more nutrients than they can process. This can lead to:

• Leaf burn: Brown, crispy edges and tips on leaves.
• Tip curl: Leaves may curl downward or curl up at the edges.
• Dark green foliage: Often a sign of excess nitrogen.

How to fix it:

Flush your medium with plain, pH-balanced water to wash away excess salts. Once runoff EC matches your target range, reintroduce nutrients at a lower strength. Regularly checking runoff or reservoir EC will help prevent any future buildups.

Signs of underfeeding

When EC is too low, plants aren't receiving enough minerals to support growth. Symptoms include:

• Pale leaves: A general yellowing, especially of lower leaves, often indicates nitrogen deficiency.
• Stunted growth: Weak stems, smaller leaves, and slow development.
• Early leaf drop: The plant may sacrifice older leaves to redirect nutrients to new growth.

How to fix it:

Increase nutrient strength gradually until EC readings match the target range for your plant's growth stage. Keep a log of adjustments and plant responses to fine-tune your feeding routine.

Final tips for EC management

As you can tell by this point, consistent monitoring is key to mastering EC for cannabis. Keep a grow log to track your readings, nutrient mixes, and plant responses. This makes it easier to spot patterns and finely tune your feeding routine. Always monitor runoff to understand what's happening in the root zone, especially when growing in soil or coco. And remember, EC works hand in hand with pH; even the perfect EC won't help if your pH is off, so balance both for optimal nutrient uptake. For more details, see our How to Adjust pH Level When Growing Cannabis article.

By staying proactive and attentive, you'll avoid common feeding mistakes, ensure optimal plant health, and ultimately enjoy bigger, higher-quality harvests.