Divisi
When to plant Irish potato in Tarmount
M'Sila, Algeria
The Irish potato (mbatatisi, ikirayi, viazi mviringo) is a cool-weather crop grown for the tubers that swell underground — it is not a grain, and it is not the same plant as sweet potato.
| Fit | Favourable |
|---|---|
| When to plant | 21 Jan 2027 – 2 Mar 2027 opens in 16 weeks |
| Expected harvest | about 25.5 t/ha |
| Harvest | From 1 Apr 2027 to 10 Jul 2027, depending on the planting date |
| Ready to harvest | 70–130 days after planting |
| Work it takes | 110–185 days per hectare, by hand |
Rain-fed. These dates are worked out from each place's own rainfall, for a field watered by the season — with irrigation a window can open earlier, close later, or come round more than once a year. Check your own field under What grows, or get the Divisi app for a calendar dated to your farm.
If you only get one chance to plant, aim for around 21 Jan 2027. That is the point in the window where the rains are most reliably established.
This season's rainfall outlook for Tarmount is close to normal, so these dates match the pattern the area usually follows.
Planting after 2 Mar 2027 leaves the crop short of season: it runs into the dry months before it has finished filling.
What decides this in Tarmount
| Rain and temperature | 88% |
|---|---|
| The soil | 76% |
| The lie of the land | 45% |
For irish potato in Tarmount, the lie of the land is the tightest of the three at 45%. You cannot flatten it, but you can farm it: plant along the contour rather than up and down, ridge or tie ridges to hold water on the slope, and expect shallower rooting than the crop would manage on flat ground.
The 2026 season in Tarmount
| Rain in a typical year | About 296 mm |
|---|---|
| This season's rain | Rain close to usual — plan around about 296 mm falling roughly when it always does |
| What that supports | enough rain for one short crop, and only if timed to it, warm, with a cool spell that slows winter growth |
| Ground this covers | 2 kinds of ground. The season below is the largest that farms — about 61% of this area. |
| 61% | enough rain for one short crop, and only if timed to it; warm, with a cool spell that slows winter growth 110 growing days · about 250 mm |
|---|---|
| 39% | enough rain for one short crop, and only if timed to it; warm, with a cool spell that slows winter growth 133 growing days · about 310 mm · October to March |
last updated 18 September 2026
Sloping ground holds back about 35% of yield here.
What irish potato needs to grow here
| Soil it likes | well-drained loam or sandy loam soil |
|---|---|
| Soil sourness (pH) | Happiest between pH 5.0 and 6.5 |
| Spacing | 75 cm between rows, 28 cm between plants |
| Feed it most with | potassium and magnesium |
What it takes to grow irish potato in Tarmount
| Planting material | About 47,000 plants per hectare |
|---|---|
| Nitrogen (N) | About 84 kg per hectare |
| Phosphate (P₂O₅) | About 26 kg per hectare |
| Potash (K₂O) | About 148 kg per hectare |
| In the shops | A basal compound at planting — Compound D, or an NPK blend — covers the phosphate and potash. A nitrogen top dressing — urea or AN — goes on once the crop is established. |
| Hand work | 110–185 days per hectare, by hand |
These are the nutrients a irish potato crop of that size carries off the field. What you actually apply depends on what your soil already holds — which is what a soil test, or the app's field records, tell you.
What to watch for
Grow Irish potato with a plan, not a guess
Everything above describes Tarmount as a whole — your own soil, slope and rainfall will shift the dates. The Divisi app works them out for your field, and dates each job that follows.
This calendar moves
Planting windows shift with the forecast. Leave your email and we'll send what changed, and a note when planting time nears — a couple of emails a month at most.
Frequently asked questions
Will irish potato grow well in Tarmount?
Tarmount rates as favourable for irish potato.
When should I plant irish potato in Tarmount?
Typically 21 Jan 2027 to 2 Mar 2027, forecast-adjusted.
Is this exact for my own field?
No — these are readings taken across Tarmount, not on your field. Soil, slope and rainfall change from one farm to the next. Check your own location to see your own numbers.
