Temba Dube
THE “start of season” is the point when conditions are considered reliably wet enough to plant crops with a reasonable expectation of successful germination and establishment. Scientists use several criteria to define this:
AREX/AGRITEX Criterion
Definition: Plant after 25mm of rain falls within 7 days.
Advantage: Allows for the earliest possible planting, giving plants a longer growing window and a shot at the best market prices.
Weakness: Carries a 50 percent risk of a “false start” there’s a real chance the rain will stop, causing seedling failure and forcing expensive replanting.
. MET (Meteorological Services Department) Criterion
Definition: Plant after 40 mm of rain falls within 15 days.
Advantage: Reduces false start risk to 40% (2 out of 5 years). Still early enough for a good season, but with greater reliability.
Weakness: Slightly delays planting (about a week later than AREX), which can shorten the season and affect early market opportunities.
. DEPTH (Soil Moisture) Criterion
Definition: Plant after 40 mm of rain in 4 days, and soil moisture reaches 25 cm depth.
Advantage: Most reliable-just a 25 percent risk of false start (1 in 4 years). Virtually ensures enough moisture for seedlings to survive.
Weakness: Latest planting (2–3 weeks after AREX), which can slightly lower yields or market timing, especially if the season ends early.
How does this week’s forecast fit in?
The forecast shows intermittent rain in most cities enough to dampen the soil, but unlikely to meet the MET or DEPTH thresholds in most areas.
Best Practice: Don’t plant after the first shower. Wait for multiple, closely spaced rain events and check your own rainfall totals.
Prepare don’t rush. Use this time to finalise land prep, acquire seed and ready your irrigation or field equipment.
Special advice by crop and practice
For Rainfed Maize, Soybeans, and Other Crops
Use a rain gauge wait for at least 40 mm over 15 days (MET), or check for deep soil moisture (DEPTH).
Risk-tolerant? Plant after 25 mm in 7 days (AREX), but budget for possible replanting.
For farmers with irrigation
You have flexibility!
Plant when ready rain is a bonus, not a requirement.
Use irrigation for germination and early establishment.
For drip, sprinkler, or furrow systems, synchronize with rainfall for best water use.
For tobacco farmers
Irrigated seedbeds: Continue with transplanting as planned.
Rainfed: Wait for consecutive rainy days, ideally matching MET/DEPTH for safe establishment.
Transplanting: Ensure soil is moist to 25 cm; irrigate if needed.
For Wheat Growers
If mature: Harvest early to avoid rain damage and sprouting.
If not mature: Monitor for disease; protect grain post-harvest.
Summary Table: Start of Season Options
Criterion Definition Advantage Weakness
AREX/AGRITEX 25 mm rain in 7 days Earliest planting, max season length 50 percent chance of crop failure (high risk)
MET 40mm rain in 15 days Balances risk and opportunity Planting is 7-10 days later than AREX
DEPTH 40 mm rain in 4 days, 25 cm wet soil Most reliable, lowest failure risk (25 percent) Planting is 2–3 weeks later, possible lower yield
Let the science and the sky guide you:
Early rain is not always safe rain.
Choose your planting window based on your resources, risk appetite, and whether you have irrigation.
For wheat: harvest as soon as possible if mature. For tobacco: irrigate or wait for full soil moisture before transplanting.
A prepared farmer is a successful farmer. Monitor, measure, and act wisely for a thriving 2026 season! The forecasted rain is promising but scattered. Science and experience agree: true planting
safety comes not from the first rain, but from enough rain, over enough days, for real soil moisture. Use the next week to prepare your fields and watch the sky but hold off on planting until your
local rainfall meets the tested thresholds.
Let’s farm smart, not just fast.
Mugiyo Hillary (PhD, Chief Director) Mrs Magwenzi, Director MSD — Mrs Manzou and Prof O Jiri
