Building Your Own Feed Schedule

What a feed schedule actually is

A feed schedule is a written plan that tells you, week by week, what nutrients to deliver to your plants, at what concentration (EC or ppm), at what pH, and at what frequency. It's not the bottle label. The label is a maximum-sales chart written by the company selling you bottles Anecdote.

A good schedule answers four questions for each irrigation:

1. What nutrients am I adding (N-P-K plus secondary and micronutrients)?
2. What is the final EC and pH of the solution going in?
3. What is the runoff EC and pH coming out (in soil/coco)?
4. What did the plant look like 24 hours later?

Everything else — silica, kelp, fulvic acid, microbes, bloom boosters — is an optional layer on top of a working base. Build the base first.

Why growers build their own instead of following the bottle chart

Manufacturer charts are calibrated to make their full product line look necessary. They typically overshoot EC for hobby setups, assume RO water, and ignore the nutrients already present in soil or coco coir buffering charges.

Real reasons to build your own:

• Your tap water isn't theirs. Hard tap water can already sit at 0.4–0.6 EC with significant calcium and magnesium ^[1]. Adding a full-strength Cal-Mag dose on top is how you get lockout.
• Your medium isn't neutral. Pre-charged ('buffered') coco and most peat-based soils contain starter nutrients. Living soil may need almost no bottled inputs at all ^[2].
• Your strain isn't average. Some cultivars run hot at EC 1.4; others want 2.0+ in late flower. The only way to find out is to observe Weak / limited.
• You save money. Half to two-thirds of a manufacturer's product stack is usually redundant or low-impact.

The goal isn't a perfect schedule. It's a schedule you understand and can adjust.

When to start

Start tracking from the first feed after transplant into your final container. Seedlings and fresh clones generally need very little — plain pH-adjusted water or roughly 0.4–0.6 EC of a mild veg solution is plenty for the first 1–2 weeks Weak / limited.

If you're switching to a custom schedule mid-grow, do it at a natural transition: the move from veg to flower, or right after a transplant. Don't change feed strategy in the middle of a stress event (heat wave, pest treatment, defoliation).

How to build one, step by step

Step 1: Test your source water. Measure EC and pH straight from the tap (or RO unit). If EC is above ~0.3, get a water report from your municipality or test for calcium, magnesium, and sodium. High-sodium water (>50 ppm) is a real problem and may require RO or rainwater ^[1].

Step 2: Pick a base nutrient line. A two-part (A+B) or three-part (Grow/Micro/Bloom) line covers nearly all needs. Common reputable options: General Hydroponics Flora series, Jacks 321, Athena Pro, Canna, House & Garden. Brand matters less than consistency.

Step 3: Set EC targets by stage. Use these as starting points, not gospel:

• Seedling / early veg: 0.6–0.9 EC
• Late veg: 1.2–1.6 EC
• Early flower (weeks 1–3): 1.4–1.8 EC
• Peak flower (weeks 4–6): 1.6–2.0 EC
• Late flower / ripening: 1.2–1.6 EC, tapering

These are input ECs measured at the standard 1:1 conversion (0.7 scale: 1.0 EC ≈ 700 ppm). Hydro typically runs lower than coco; soil lower than both Weak / limited.

Step 4: Set pH targets by medium.

• Hydro/coco: 5.6–6.2
• Soilless peat mix: 6.0–6.5
• Living soil: 6.3–6.8 (and largely self-regulating) ^[3]

Step 5: Mix in the correct order. Silica first (it's high pH and needs to disperse), then Cal-Mag if used, then base A, then base B, then additives. Stir between each. Check EC, then adjust pH last.

Step 6: Feed, then measure runoff. In coco and soil, collect 10–20% runoff and measure its EC and pH. Runoff EC higher than input means salts are accumulating — back off concentration or increase irrigation volume. Runoff EC lower than input means the plant is eating hard — you can push more Weak / limited.

Step 7: Write everything down. Date, stage, input EC, input pH, runoff EC, runoff pH, volume per plant, and a one-line plant observation. After two grows you'll have a schedule tuned to your room, not someone's marketing department.

Common mistakes

• Chasing the chart instead of the plant. If leaves are clawing and tips are burnt, your EC is too high regardless of what week the chart says.
• Not accounting for water hardness. Adding Cal-Mag to already-hard tap water is the single most common cause of calcium/magnesium excess and resulting micronutrient lockout Weak / limited.
• Adjusting pH before EC. Adding nutrients changes pH. Always pH last.
• Stacking too many additives at once. If you add four new bottles in week three and something goes wrong, you have no idea which one caused it. Change one variable at a time.
• Flushing on instinct. A long plain-water 'flush' at the end of flower has no demonstrated effect on smoke quality in controlled testing ^[4]. Tapering EC and ending with light feeds is sufficient.
• Trusting ppm numbers across meters. TDS meters use different conversion factors (0.5, 0.64, 0.7). Always record EC — it's the unambiguous unit.

Related techniques and reading

Building a feed schedule sits inside a larger cultivation toolkit:

• Reading nutrient deficiencies — how to tell a real deficiency from a pH problem.
• Coco coir basics — buffering, drybacks, and why coco feeds differently than soil.
• Living soil — the alternative path where the soil microbiome handles most of the feeding.
• EC and pH meter calibration — your numbers are only as good as your meters.
• Runoff testing — the feedback loop that closes the schedule.

Sources

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