Growth Rate Tracker for Plants | Monitor & Predict Harvest Time

Key Takeaways

What it does: Calculates daily growth rate in cm/day from your initial and final height measurements, then estimates how many days until harvest maturity.
50+ crop profiles: Hydroponic and soil crops each have target growth rates — the tracker tells you if your plant is growing slower, on track, or faster than expected.
Light hours input: Enter your daily light hours to see whether light schedule is contributing to growth rate — links to the Light Schedule Calculator for adjustments.
EC input: Enter your nutrient EC reading alongside growth data to correlate nutrient strength with growth performance over time.
Pro Tip: Measure at the same time each week — plant height changes with temperature and time of day. Consistent measurement time gives more accurate growth rate calculations.

Plant Growth Rate Tracker

Enter your plant’s measurements and growing conditions to calculate daily growth rate and estimated harvest date.

Crop Category

Select Crop

Initial Height (cm)

Measure at the start of your tracking period.

Current Height (cm)

Measure today at the same point on the plant.

Days Between Measurements

Light Hours Per Day

Optional — used to assess light contribution.

Nutrient EC (mS/cm)

Optional — check with EC Calculator.

Your Growth Rate Results

Daily Growth Rate

—

cm / day

Total Growth

—

cm in period

Est. Days to Maturity

—

days remaining

—

Why track plant growth rate?

Growth rate is the most direct signal of plant health in a hydroponic system. A plant that grows 2 cm/day on Monday and 0.5 cm/day by Friday is telling you something changed — whether it’s a nutrient imbalance, a lighting problem, or the beginning of root rot. Without tracking, you only notice problems when they’re visible in leaf color or wilting — by which point significant damage has already occurred.

Tracking growth also lets you predict harvest timing with real data rather than guessing from a seed packet. If your lettuce needs to reach 25cm and is currently growing at 1.8 cm/day, you know you have approximately 14 days left — which lets you plan your next seeding round, nutrient reservoir change, and market sales schedule precisely. Use growth rate data alongside your EC readings and pH measurements to build a complete picture of your system’s performance.

How to use this growth rate tracker

Select crop category and crop: Choose Hydroponic or Soil-Based first, then pick your specific crop. The calculator uses crop-specific target growth rates to classify your result as slow, normal, or fast.
Enter initial height: This is the plant height at the START of your measurement period. Measure from the soil surface (or net pot rim in hydroponics) to the highest growing point. Use a ruler, not a tape measure — precision matters for accurate daily rates.
Enter current height: Today’s measurement at the same reference point. For the most useful data, measure at the same time of day — plants are typically taller in the afternoon after a full day of photosynthesis.
Enter days between measurements: How many days passed between the initial and current measurement. 7 days (weekly) is ideal — daily measurements add noise while monthly measurements miss important changes.
Enter light hours and EC (optional): Adding light hours helps identify if insufficient light is limiting growth. EC data from your EC/TDS Calculator helps correlate nutrient strength with growth performance.
Click Calculate: The tracker shows your daily growth rate, total growth in the period, and estimated days remaining to harvest maturity based on a typical final height for your crop.

Pro Tip: Record measurements in a simple spreadsheet — date, height, EC, pH. After 4–6 weeks you’ll have a growth curve that shows exactly how your system performs over time. This data is invaluable for troubleshooting slow periods and proving your system works when it’s growing well.

Expected growth rates by crop

Crop	Typical Growth Rate	Mature Height	Key Notes
Lettuce (Hydroponic)	1.5–2.5 cm/day	20–30 cm	Fast grower. Slow growth usually means low EC or insufficient light.
Basil (Hydroponic)	1.0–2.0 cm/day	30–50 cm	Growth slows sharply when flowering begins — pinch flowers immediately.
Tomatoes (Hydroponic)	2.0–4.0 cm/day	100–200 cm	Indeterminate varieties grow indefinitely — track internodal spacing, not just height.
Peppers (Hydroponic)	0.5–1.5 cm/day	60–120 cm	Naturally slower than tomatoes. Rate drops during fruiting — this is normal.
Cucumbers (Hydroponic)	3.0–6.0 cm/day	150–300 cm	Fastest common hydroponic crop. Needs daily training and support.
Spinach (Hydroponic)	1.0–1.8 cm/day	15–25 cm	Growth stops in heat above 24°C — track temperature alongside height.
Strawberry (Hydroponic)	0.3–0.8 cm/day	20–30 cm	Slow height growth is normal — track runner production and fruit count instead.
Microgreens	0.5–2.0 cm/day	5–10 cm	Harvested at 7–14 days. Track days-to-harvest not height for these crops.

Growth problems — causes and fixes

Problem	Cause	Fix
Growth rate suddenly drops	Nutrient deficiency, pH drift, or root zone issue	Check EC and pH immediately. Root issues show as slow growth before visible symptoms appear.
Growth rate normal but no fruiting	Nitrogen too high relative to Phosphorus and Potassium	Switch to flowering-stage nutrients. Use Nutrient Calculator to recalculate NPK ratio.
Leggy, fast upward growth with weak stems	Insufficient light — plant stretching toward source	Lower lights or increase hours. Use Light Schedule Calculator to optimise photoperiod.
Growth stops completely	Temperature extreme, root rot, or complete nutrient lockout	Check water temperature (keep below 22°C). Inspect roots for brown slime. Check pH — values below 5.0 or above 7.5 lock out all nutrients.
Uneven growth between plants in same system	Uneven flow, blocked emitters, or shading between plants	Check each emitter output. Ensure plants are properly spaced using the Plant Spacing Calculator.
Slower growth than expected for crop type	Light hours insufficient for growth stage	Increase light to 16–18 hours for vegetative growth. Check light intensity — too far from canopy reduces PAR significantly.
Harvest taking longer than estimated	Growth rate lower than average due to seasonal light changes	Normal in winter months when ambient light decreases. Supplement with grow lights. Recalculate estimate using actual measured growth rate.

Growth tracking: hydroponics vs soil

Hydroponic growth tracking

Hydroponic plants typically grow 20–50% faster than soil equivalents because nutrients are delivered directly to roots without the energy cost of soil penetration. This makes growth rate tracking especially valuable — small deviations from expected rates are detectable earlier and more precisely. Track EC with the EC/TDS Calculator weekly alongside height measurements. The combination of growth rate + EC trend tells you whether slow growth is a nutrient problem or an environmental one.

Soil plant growth tracking

Soil crops have more variable growth rates due to seasonal temperature changes, soil nutrient fluctuations, and weather. Tracking is still useful but measure every 2 weeks rather than weekly — soil growth is more gradual. Pair growth tracking with the Soil NPK Calculator to see if fertilization timing correlates with growth surges. For root vegetables like carrots and potatoes, track leaf canopy spread rather than plant height.

Frequently Asked Questions

How often should I measure plant height for tracking?

Weekly measurements give the best balance of accuracy and practicality. Daily measurements add noise from temperature and humidity fluctuations — a plant might appear to grow 3cm one day and 0.5cm the next just from measurement conditions. Monthly measurements are too infrequent to catch problems early. Seven days is the standard interval used by commercial hydroponic growers for growth rate monitoring.

What is a good growth rate for hydroponic lettuce?

In a well-managed hydroponic system, lettuce should grow 1.5–2.5 cm per day during the vegetative stage. At this rate, a plant starting at 5cm should reach 25cm in approximately 8–13 days. If your lettuce is growing at less than 1 cm/day, first check EC (target 1.2–1.8), then pH (target 5.8–6.2), then light hours (should be 14–16 hours). These three factors account for the majority of slow growth cases in lettuce.

Why is my harvest estimate different from what the seed packet says?

Seed packet timelines are based on ideal outdoor soil conditions and average sunlight. In hydroponics, plants typically mature 20–40% faster than these estimates because of optimised nutrition and light. Conversely, in winter or poor lighting conditions, they may take longer. This tracker calculates your estimate from your actual measured growth rate — which is always more accurate than a generalised seed packet figure. Use the tracker’s estimate rather than the packet once you have 2+ weeks of real growth data.

Can I track root vegetables with this tool?

For root vegetables like carrots, radishes, and potatoes, height tracking is less meaningful than for above-ground crops. Instead, track leaf canopy spread or the number of healthy leaves as your growth indicator. Enter the canopy diameter in centimetres in the height fields — the growth rate calculation still works accurately with any consistent linear measurement. Germination timing for these crops is managed by the Seed Germination Timer.

How does light hours affect my growth rate calculation?

Light is the primary driver of photosynthesis — and therefore growth. Every additional hour of quality light (within the 12–18 hour range) increases the daily photosynthesis window. The tracker uses your light input to flag whether insufficient light could be limiting your rate. For most vegetative crops, 16 hours of light per day is optimal. Flowering and fruiting crops often need 12 hours to trigger the flowering response. Use the Light Schedule Calculator to plan your photoperiod for each growth stage.

Related gardening tools

Growth rate tracking works best as part of a complete monitoring routine. These tools connect directly to the factors that drive or limit growth.

EC/TDS Calculator — check nutrient concentration alongside every growth measurement. pH Calculator — confirm pH is in range when growth rate drops unexpectedly. Light Schedule Calculator — optimise photoperiod for each growth stage. Plant Spacing Calculator — ensure adequate space isn’t limiting growth potential.