Garden Update — Wednesday, 18 March 2026
Daily insights generated from live sensor and weather data, compared across 3 AI models. Sensor data from Ecowitt GW1200 · Weather from Open-Meteo · Dunedin, NZ
Live Sensor Readings (Ecowitt)
| Sensor | Value |
|---|---|
| Outdoor temp | 16.4°C (feels like 16.4°C) |
| Outdoor humidity | 72% |
| Dew point | 11.3°C |
| Soil moisture (ch1) | 45% |
| Wind | 0.0 km/h (gusts 0.0 km/h) |
| Rain today | 0.0mm |
| Solar radiation | 0 W/m² |
| UV index | 0 |
| Pressure | 1001.6 hPa |
7-Day Weather Forecast
| Date | Max | Min | Rain | Rain% | Wind | UV | ET₀ | Radiation |
|---|---|---|---|---|---|---|---|---|
| 18/03 | 17.6°C | 11.6°C | 3.7mm | 83% | 31kph | 5.5 | 2.3mm | 13.0MJ/m² |
| 19/03 | 16.1°C | 10.9°C | 0.0mm | 0% | 17kph | 5.5 | 2.2mm | 15.3MJ/m² |
| 20/03 | 15.6°C | 9.6°C | 0.0mm | 0% | 9kph | 5.0 | 1.4mm | 8.3MJ/m² |
| 21/03 | 18.3°C | 10.3°C | 0.0mm | 0% | 9kph | 5.5 | 2.6mm | 17.3MJ/m² |
| 22/03 | 17.6°C | 12.3°C | 0.0mm | 18% | 6kph | 5.3 | 2.1mm | 14.0MJ/m² |
| 23/03 | 17.5°C | 11.7°C | 0.0mm | 3% | 7kph | 5.0 | 2.5mm | 18.2MJ/m² |
| 24/03 | 18.0°C | 10.1°C | 0.0mm | 0% | 7kph | 4.5 | 2.2mm | 15.2MJ/m² |
Generated at 7:47 AM NZDT
AI Model Comparison
⚠️ 2 model(s) did not respond:
claude-opus-4-6,claude-sonnet-4-6
🟢 OpenAI — gpt-5.4
The brassica bed is still in the safe moisture zone at 45%, but it has dried steadily from 49–52% a week ago and the last 7 days are running a water deficit overall. At just 18 days from planting, all broccoli, cauliflower, and cabbage are still in early establishment, so the key job today is to protect even moisture rather than push growth.
Observations
- Soil moisture has fallen from 49–52% on 11–14/03 to 45% on 16–18/03 → the whole brassica bed is drying into the lower half of the ideal range, especially relevant for recently planted broccoli and cauliflower still building root systems.
- Past-7-day rain totals 19.7mm while past-7-day ET₀ totals 15.3mm, but since planting the bed has only had 19.7mm rain against about 22.3mm ET₀ from 10–18/03 → the post-planting period is in a small accumulated moisture deficit despite the acceptable sensor reading today.
- Forecast rain in the next 3 days is only 3.7mm, while ET₀ from 18–20/03 totals 5.9mm → expected moisture losses exceed incoming rain, so the current drying trend is likely to continue rather than recover.
- Wind is forecast to reach 31.3kph today and the bed is already under fine mesh → the existing netting is more likely to act as a sail, raising the chance of rubbing or lifting around young brassicas.
- Today’s minimum is 14.5°C and live air temperature is 16.4°C → aphid pressure is plausible in sheltered growing tips, but cabbage white flight is less favoured right now by the current zero solar radiation and forecast wind.
Actions for Today
-
Brassica bed — early establishment 45% soil moisture + a decline from 49–52% last week to 45% now + only 3.7mm rain forecast against 5.9mm ET₀ over the next 3 days → the bed is not dry yet, but it is drifting toward deficit while roots are still shallow → water once today if the forecast rain has not arrived by late afternoon: apply 6–8L/m² evenly over the bed in the evening, about 22–30L total for 3.74m², delivered as a slow soak under the mesh.
-
Broccoli, cauliflower, and cabbage — early establishment Today’s wind forecast of 31.3kph + full-bed fine mesh already installed since 28/02 → wind load on the cover is the immediate mechanical risk, not insect pressure → check and secure the netting edges and supports today before the strongest wind, tightening any slack spans so leaves do not chafe against the mesh.
-
Brassica bed — early establishment Maintenance log shows comfrey mulch applied on 12/03, 6 days ago, while the notes still say “Mulch: none applied yet” + soil moisture is trending downward → the record is inconsistent, and mulch status now affects watering frequency calculations → verify whether the comfrey leaves still cover the soil surface; if coverage is patchy, top up to a light continuous layer around but not against stems after watering.
Skip today
- Blanching cauliflower heads — all three cauliflowers are only 18 days from planting, far too early for curd-covering work.
- Feeding again with tonic or fertiliser — establishment feed was given on 28/02 and there is no data sign of nutrient stress; the current issue is moisture trajectory, not feeding.
- Harvesting any broccoli or cabbage — all plants are still in juvenile vegetative growth, well before the May–July harvest window.
Variety Watch
Green Dragon, Purple, and Side Sprouter broccoli — early vegetative phase — keep moisture even while roots are still shallow
White, Cheddar, and Violet cauliflower — early vegetative phase — too young for blanching; steady moisture matters most now
Lion Heart, Dutch Red, and Cannonball cabbage — early vegetative phase — hold growth steady through the current drying trend
Looking Ahead
The main shift is not heat but cumulative drying: from 18–20/03, only 3.7mm rain is forecast against 5.9mm ET₀, so the bed may slip below the current 45% if left to the weather alone. After today’s windy spell, the next few days look calmer and mostly dry, which will make any missed watering show up clearly in the sensor trend.
Horticulture
Young brassicas depend on uninterrupted cell expansion in their newest leaves while their root systems are still sparse and localized around the transplant hole. When soil moisture fluctuates, the plant has to repeatedly adjust water potential in its tissues, which slows leaf area expansion even before visible wilting appears. That matters because leaf area is the engine that powers later head, curd, or heart formation. A light mulch reduces evaporation from the soil surface, but it also moderates temperature swings in the topsoil, which helps fine feeder roots keep growing. In cool maritime autumn conditions, steady water supply usually matters more than sheer quantity.
The bed sat under still, damp air this afternoon, with the sensor holding at 45% and no sun on the leaves.
This post was auto-generated by the Garden AI pipeline. Weather data from Open-Meteo · Claude & GPT insights · Built with Astro