How Much Seed Potato Do You Need Per Hectare, and What Will It Cost?

It is the question we field more than any other, usually in a WhatsApp message a few weeks before planting: how much seed do I need, and what is it going to cost me?

Here is the honest answer, the arithmetic behind it, and the four costs that catch growers out every season.

The short answer

Budget 1 700 kg to 2 500 kg of certified seed potatoes per hectare. At an indicative R12 per kg, or roughly R300 per 25 kg bag, that puts your seed line between R20 400 and R30 000 per hectare.

• 1 700 kg per hectare: 68 bags, about R20 400
• 2 000 kg per hectare: 80 bags, about R24 000
• 2 250 kg per hectare: 90 bags, about R27 000
• 2 500 kg per hectare: 100 bags, about R30 000

Those prices are indicative and move with variety, grade, season and volume. Confirm the current figure with us before you build a budget on it.

Where the range comes from

An 800 kg spread per hectare is not vagueness. It is three real decisions.

Seed size. Larger tubers weigh more per plant. If you plant a 60 mm grade instead of a 35 mm grade at the same spacing, your kilograms per hectare climb even though your plant population has not changed. Small grades stretch further per bag.

In-row spacing. Tighter spacing lifts plant population, which lifts total tuber numbers and pushes size distribution smaller. That suits a pre-pack or seed market. Wider spacing produces fewer, larger tubers, which suits a processing or bulk ware market. Your market sets your spacing, and your spacing sets your seed bill.

Whether you cut. Cutting seed stretches a bag further and reduces cost per hectare. It also opens every cut surface to soil-borne infection and needs clean blades, careful handling and suberisation time. On a small, well-managed block it can work. On a rushed 20 ha planting it is a false economy.

The four costs growers leave out

The bag price is the number everyone compares. It is rarely the number that decides the season.

1. Getting it there. Certified seed is heavy and it is bulky. A hectare of seed is close to two tonnes of freight. Work out the delivered cost per hectare, not the ex-store cost per bag. On a 5 ha block, transport can move your effective seed price by a rand a kilogram or more, depending on distance.

2. Keeping it cool. Seed that sits in the sun on the back of a bakkie for two days is no longer the seed you paid for. Sprouting, dehydration and heat stress all reduce emergence. If you do not have cold storage, plan your collection date around your planting date, not around your diary.

3. Shrinkage and grade-out. Some of every consignment will not be plantable by the time you get to the field. Build a contingency into your order rather than discovering the shortfall on planting day, when the variety you wanted is gone for the season.

4. What the seed is carrying. This is the one that costs the most and shows up the latest. Uncertified or farm-saved seed carries the virus and disease load of the crop it came from. You do not see it in the bag. You see it in the yield, three months later, and by then the money is spent.

Why the cheapest bag is rarely the cheapest hectare

Run the sum on a realistic block.

Say seed is R25 000 of your per-hectare cost. If a cheaper, uncertified line saves you R6 000 on the seed and costs you 15% of a 45 t/ha crop, you have given up close to 7 t of saleable potatoes to save R6 000. There is no ware price at which that trade works.

This is why we only supply certified material. RegenZ supplies a mix of open varieties across Southern Africa, with our focus on Valor and Mondial grown by KwaZulu-Natal seed growers, and field multiplication by Ivanhoe Farms and Pidelta. A large share of that volume goes to buyers in Zimbabwe. Every step in that chain exists to protect what is inside the bag.

Plan your order backwards from your planting date

Seed potato supply is not a stock item you order on Thursday for Monday. It is a crop, grown a season ahead, in limited volume, in specific grades. Popular varieties in popular grades sell out.

Work backwards:

• Six to nine months out: decide your market. Pre-pack, processing, ware, or seed. That decision drives variety and grade.
• Four to six months out: place the order. Name the variety, the grade and the delivery window. This is when availability still exists.
• Three months out: get your soil analysis back and finalise the fertiliser programme, so nutrition is planned before the seed arrives, not after.
• Two to four weeks out: confirm the delivery date and make sure you have somewhere cool to put close to two tonnes per hectare.

The growers who get the variety they want are simply the ones who asked earliest.

Test the soil before you buy the seed

There is a sequencing mistake we see constantly. Seed gets ordered, land gets prepared, and the soil analysis happens somewhere in the panic of the last fortnight, if at all.

Potatoes are sensitive to pH and to calcium and potassium balance. If your pH is wrong, you cannot correct it in the week before planting. Lime needs months to react. A soil result in hand six months out lets you fix the cheap constraints before you commit the expensive input.

A Standard Soil Test through our lab service is R414. A Comprehensive Soil Test is R1 167. Against a seed bill of R25 000 and a full input programme well beyond that, it is the least expensive decision in the season and it changes more of the outcome than any other. Sampling spec is straightforward: 500 g of soil from at least five points per hectare, at 15 cm depth.

Frequently asked questions

How many 25 kg bags of seed potatoes do I need per hectare?

Between 68 and 100 bags, depending on seed grade and in-row spacing. Most commercial plantings land between 72 and 88 bags per hectare.

Which varieties does RegenZ supply?

We supply a mix of open varieties, with Valor and Mondial as our main focus, grown by KwaZulu-Natal seed growers. Availability differs by grade and by season, so ask early.

Can I plant potatoes I grew myself?

You can, and yields will decline as virus load builds up over successive generations. It is the single most common reason a potato block underperforms. If budget forces it, at least rotate certified seed back in periodically rather than replanting indefinitely.

Is it cheaper to cut seed?

Per hectare, yes. It also raises disease risk and demands clean equipment and correct handling. Worth considering on a small, closely managed block. Not worth it at scale or under time pressure.

When should I place my seed potato order?

Four to six months before planting for the best variety and grade availability. Earlier if you need a specific variety in a specific grade.

Do you deliver outside South Africa?

We supply growers across Southern Africa, and Zimbabwe is a major market for us. Volumes, permits and lead times differ by country, so talk to us early in your planning.

Get a quote for your block

Tell us your hectares, your target market and your planting window, and we will come back with a variety recommendation, a grade, a seed rate and a delivered price. Start on our bulk seed potato page or message us on WhatsApp on +27 60 319 8990.

If you are watching what comes next in potato genetics, our work on hybrid true potato seed looks at a planting material that ships in an envelope rather than on a truck.

Prices quoted are indicative at the time of writing and subject to change. RegenZ does not employ a SACNASP-registered agronomist. Agronomic guidance in this article is indicative and is intended to support, not replace, advice from a registered professional.