In aquaponics, the success of a season depends mainly on good upstream calendar management : periods of sowing, planting, ramp-up… and times when it is better not to intervene.
Unlike a traditional vegetable garden, aquaponics operates in a closed loop, where water, fish, plants, and bacteria are closely interconnected. Every decision directly influences the overall balance of the system.
In aquaponics, plant and fish growth depends directly on a significant number of invisible but essential parameters : water temperature, bacterial activity, oxygenation, and filtration capacity. Two systems located in the same region can therefore develop at very different rates, depending on their maturity or the level of organization of the aquaponic system.
An effective aquaponics calendar doesn't just tell you "what to plant." Its main purpose is to avoid biological spikes : waste, unassimilated nutrients, and oxygen consumption. Proper timing allows for a gradual ramp-up, which secures the entire system and makes production much more consistent over time.
This month-by-month aquaponics calendar, from February to October, has a simple objective : to help you progress at the right pace, according to the biology of the system, and not a simple sowing calendar.
The water must remain clear and stable over time. Water that turns cloudy after every intervention is a warning sign: either the mechanical filtration is insufficient, or particles are being introduced into the system.
Nitrite levels must stay at zero. Any rise in nitrites indicates that the biofilter is no longer coping with the current load.
The fish must display normal behaviour and a regular appetite. A drop in appetite or fish gasping at the surface often signals an oxygen or water quality problem.
Finally, the plants must show continuous growth, even if modest. Prolonged stagnation or pale leaves generally point to a problem with conditions (temperature, pH, oxygen).
January is the month of invisible preparation. The system is still ticking over slowly, but it's time to start planning for the season ahead.
It's a good moment to check the core parameters, carry out any necessary maintenance on equipment, and schedule the next seedlings. A few seedlings can be started outside the system towards the end of the month, so you enter February with a head start, without rushing the restart.
February is the month for intelligent restarting. The system often comes out of a period of inactivity : the biofilter is less active, deposits have accumulated, and circulation may be uneven.
When it comes to plants, we favor off-system sowing : easy-to-grow leafy vegetables and herbs. This allows us to produce uniform plants without putting too much strain on the filtration system. From a technical standpoint, now is a good time to check the circulation, lightly clean the mechanical filtration, and ensure that oxygenation is sufficient.
What you should avoid in February : accelerating feeding or planting directly into the system thinking you're "starting the season." In aquaponics, forcing the start almost always has negative consequences later on.
March marks the start of the first transplanting, but always in a gradual way. Plants go in in small batches so you can observe how the water and biofilter respond after each addition.
The best crops to focus on are short-cycle varieties: lettuces, rocket, and microgreens. They take up nutrients quickly and help stabilise the ecosystem. At the same time, summer crops can be started as seedlings in a heated propagator, but kept outside the system for now.
It is often in March that the first water-clarity issues appear. Effective mechanical filtration, properly maintained at this stage, prevents a large proportion of the problems that arise in spring.
April is a key month for establishing stability. Light levels increase, temperatures become more consistent, and the system's biology is more active.
You can gradually increase the density of leafy vegetables, introduce more herbs, and begin organising the space for larger crops. It is also the time to monitor pH trends: a poorly adjusted pH can block the uptake of certain nutrients even when the system appears to be running well.
To avoid: making several major changes over a short period. In aquaponics, imbalances are often the result of too many actions carried out too quickly.
May is the month of transition. If the system is stable, you can begin introducing more demanding plants such as tomatoes, cucumbers, or basil.
The key is to progress gradually. Each new nutrient-hungry crop increases the demand on the system. Keeping a rotation of leafy vegetables as a base helps absorb fluctuations and protect the overall balance.
Consistent circulation and clean mechanical filtration become essential to prevent waste accumulating.
In June, the system can enter full operation. Plants grow rapidly, fish are active, and nitrification is efficient.
The main risks are excessive plant density and overfeeding of fish. Too much vegetation creates poorly ventilated, humid areas that favor pests and diseases. Regular harvesting not only increases yields but also helps stabilize nutrient consumption.
Maintenance should remain light but consistent : frequent small actions are far preferable to a late, major cleanup.
July is often the most technically demanding month. Warm water holds less oxygen, while both fish and bacteria are consuming more of it.
Priority should be given to oxygenation, circulation, and shielding the circuit from direct light. Algae and fish stress almost always appear when these points are neglected. It is equally important to avoid overfeeding the fish.
Installing a ventilation system is also important during this season.
August is a month of continuity and anticipation. The system has already produced a lot and may show signs of fatigue if maintenance is irregular.
It's also an excellent time to start sowing leafy vegetables and herbs for autumn. This early planting helps avoid a production gap in September.
September is often compared to a second spring. Temperatures are milder, the system is still warm, and short-cycle crops perform very well again.
It is the ideal time to rebalance after summer : gradually reduce nutrient-demanding crops, strengthen short rotations, and stabilize the system before autumn.
Care must be taken not to remove plant biomass too abruptly, as this may trigger a rise in nitrate levels.
In October, the goal is to slow down without disrupting the balance. Cool nights slow down the fish and the biofilter, but the system can remain productive with suitable crops.
The transition must be gradual : no sudden reduction in feeding, no complete cessation of planting, no aggressive weeding. A system that is well supported in October will overwinter with much greater stability.
In November, the system slows down noticeably. The reduction in light and temperature cuts the activity of both the plants and the biofilter. The aim is to maintain stability, rather than continue producing.
Gradually reduce plant density and fish feeding, adapting to their actual appetite.
It's also a good time to check the flow and lightly clean the mechanical filtration, without disturbing the biological core of the system.
December is a period of active monitoring. Plant growth is minimal, fish are calm, and the system operates at a reduced level.
The key is to observe water clarity, fish behavior, and overall stability, allowing the system to run quietly.
December is also the time to review the past year, draw conclusions, and, if necessary, plan adjustments to the aquaponic system for the year ahead.
In aquaponics, success depends on timing. A well-understood schedule helps avoid imbalances, extend production periods, and significantly reduce technical problems.
Observing, progressing step by step and respecting the biological signals of the system are the keys to stable, productive and sustainable aquaponics.
Sources
Oregon State University Extension, Soil Temperature Conditions for Vegetable Seed Germination, Germination times by grow medium temperature — the basis of late-winter seedling production.
Virginia Cooperative Extension, Daily Light Integral for Greenhouse Crops (SPES-720), Daily light requirements by crop, explaining the gap between the calendar season and the production season.
Central Baltic TransFarm, Plant Selection and Requirements Report, pH and water temperature ranges used as annual reference points.
Oklahoma State University Extension, Nitrification and Maintenance in Media Bed Aquaponics, Managing ammonia and nitrite levels during spring load increases.
Oklahoma State University Extension, Principles of Small-Scale Aquaponics, Dissolved oxygen thresholds and temperature ranges by fish species.
New Mexico State University, Aquaponics Circular CR-680, Water parameters used as a monthly dashboard.
Indoors, light and temperature no longer follow the seasons. The calendar then reduces to the rhythm of seedlings, harvests and maintenance.
Planting does not load the biofilter — feeding the fish does. A wave of transplanting increases nutrient demand, and therefore the temptation to feed more; it is this increase that needs to be phased in gradually. The guiding principle is to raise the feed ration in small increments, leaving a full week of observation between each step, rather than following the seedling calendar.
Monitoring relies on three indicators, not one. Ammonia and nitrites must remain undetectable; any trace of nitrites means the bacterial population is not yet processing the load you have just introduced. Dissolved oxygen must stay above 5 mg per litre, the threshold cited in small-scale aquaponics reference sheets. pH must be kept within the window where nitrifying bacteria and plants coexist best, around 6.8 to 7.2, with 6.5 to 7.5 remaining acceptable.
If nitrites appear, the response is never to add more plants or clean the biofilter. Reduce the feed ration — sometimes suspending it for a day or two — increase aeration, and wait until readings return to zero before resuming the progression.
Four values are enough to manage a home system.
The last figure is the one that most changes how you read the calendar. It explains why a system that produces excellent lettuces in March will not carry a decent tomato before May without supplementary lighting.
Because germination speed depends on grow medium temperature far more than on the date. Extension records for lettuce give an indication of the scale: around three days to germination at 20 °C versus seven days at 10 °C, and the gap widens for species that are more sensitive to cold.
A tray placed on a cool windowsill may therefore germinate two to three times more slowly than one on a heat mat, with identical seeds. This is the practical reason why February seedlings are started outside the system, in a place where you can control the temperature.
No, and it's the most costly mistake of the season. The autumn clean-up is for mechanical filtration, deposits, strainers, and pipework. The bacterial media in the biofilter must not be rinsed under tap water or scrubbed.
If a media rinse is genuinely necessary, do it with water from the system, on a portion of the volume only, and never at the same time as a significant water change. The aim is to come through winter with an intact bacterial population, ready to get going again as soon as the temperature rises.
When you are away, the priority is not production — it is survival. Reduce feeding before you leave rather than asking a neighbour to hand out generous portions, shade the pond, and secure oxygenation, which is the fastest point of failure when the water is warm.
Harvest generously before you go, including lettuces that are still young. A lighter plant mass consumes less, dries out more slowly, and saves you from coming home to a greenhouse choked with foliage and ripe for pests. Finally, leave a simple instruction for whoever calls in: check that the pump is running and that the water is moving — nothing else.
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