Planting Our Seed Potato Experiments
Gatsby Seed Potatoes Organic
Price range: £6.95 through £57.00
The Next Stage of Our Potato Experiments 🥔🔬 23rd May - our main planting day. All potatoes planted were chitted
Summary: The experiments are now officially underway! We are using Gatsby for all our experiments to eliminate one factor.
We’ve planted potatoes of all shapes and sizes to see what really makes a difference when growing at home.
1. Normal-sized seed potatoes, chitted, 3 to a bag - this is our control.
2. Our non-chitted potatoes were planted about a month ago
3. Mixed bag - one small, one med and one large
4. 2 normal sized tubers in a bag
5. 4 normal sized tubers in a bag
6. Large Tuber cut up
7. All new shoots bar one have been removed from 3 tubers
8. Some potatoes with a bit of scab.
Will bigger seed potatoes produce bigger harvests? Will smaller tubers produce small numbers of new tubers? Does crowding more potatoes into a pot increase the crop, or just create a potato traffic jam underground? 🚦🥔 There’s plenty of gardening advice online, but we want to see the results with our own eyes and share them with you as the season unfolds.
Some of the results may surprise us! What do you think will happen? Let us know in the comments.
Growing potatoes is a bit like putting together a giant jigsaw puzzle 🧩🥔. Seed size, soil, weather, watering, spacing, feeding, variety and even simple timing can all influence the final result. There is rarely one single “perfect” method that works for everyone every year. Part of the fun (and frustration) of growing is discovering what works best in your own garden, climate and growing style 🌱🌦️.
What potato experiments are you doing in your garden this year? You could do just one with any variety - when you get your seed potatoes, you could chit half for a few weeks and plant the others immediately on arrival.
Read more about our experiments below and check back over the season for updates and results.
Our Potato Experiments
Our Control Experiment – 3 normal sized chitted potatoes
We currently advise planting 3 chitted potatoes to a bag.
These are standard, healthy, normal-sized seed potatoes that have been properly chitted before planting. We’ve planted 3 potatoes per growing bag, using what many gardeners would consider the “recommended” approach.
This setup acts as our control group — the benchmark against which all the other experiments will be compared. By keeping this traditional method as our baseline, we’ll be able to see whether smaller, larger or even scabby seed potatoes perform any differently throughout the season.🥔📊
We managed to get the weight of the 3 potatoes to exactly match the unchitted potatoes that were planted a month ago!
To Chit or not to Chit. The Waiting Game Begins 🥔⏳
We advise that potatoes are chitted as it allows them to grow when it is cold outside.
These seed potatoes were planted without chitting around a month ago, giving us the chance to compare how they perform against pre-sprouted tubers later in the season.
So far, there’s no visible activity above the soil 👀 — but that’s not unexpected. The weather has stayed quite cold since planting, and potatoes naturally slow down in lower soil temperatures ❄️🌧️. Because of that, we don’t expect these unchitted potatoes to emerge for at least another few weeks yet.
This is one of the most interesting parts of the experiment. Chitting is often recommended to give potatoes a head start, especially in cooler climates or shorter growing seasons 🌤️. By planting unchitted potatoes under the same conditions, we’ll be able to see whether they eventually catch up — or remain behind throughout the growing season.
For now, it’s a lesson in patience 🕰️🥔.
Three Different Sizes of Seed Potato – Will Size Really Matter? 🥔📏
Our seed potatoes are graded to 35–55mm, which is comfortably above the UK legal minimum size for certified seed potatoes (25mm).
A lot of growers naturally assume that larger seed potatoes will produce much bigger crops because they contain more stored energy. Smaller tubers, meanwhile, are often seen as weaker or less productive. But is that really true in the long run?
Chasing the biggest tubers may not always deliver the biggest rewards 🥔🏆.For another part of the experiment, we’ve planted one small, one medium and one large seed potato together in the same growing bag 🥔🥔🥔. This reflects the kind of natural size variation that growers commonly receive within a graded net of seed potatoes. We’ll be comparing the results against a bag planted with three medium-sized tubers, and our expectation is that the overall yield will end up being very similar. While the plants may emerge and grow slightly differently early on, we suspect the final harvest will balance out across the season.
Our seed potatoes are graded to 35–55mm, which is comfortably above the UK legal minimum size for certified seed potatoes (25mm). This experiment should help demonstrate that different sized tubers can still perform very similarly in the garden — and that a smaller potato is not necessarily an inferior one.
We already provide explanations and photographs on our FAQ pages showing the natural variation in seed potato sizes 🥔📏, but we know some customers are still disappointed when they open a net and find smaller tubers mixed in. That’s understandable; many people naturally assume bigger seed potatoes must always mean bigger harvests 🌱🧺.
One reason for running these experiments is to show real growing results rather than simply explaining the theory 🔬👀. Some of the complaints we occasionally receive are from customers finding different sized seed potatoes within the same net. In reality, this is completely normal within the seed potato industry and fully legal. Seed potatoes are graded within an accepted size range, not to one exact identical size. Natural crops always contain variation 🥔📏.We’re hoping the results will demonstrate that smaller tubers can still grow into strong plants and produce excellent crops 💪🥔
Each potato variety has its own natural average tuber size, and that can also change from year to year depending on growing conditions 🌦️🥔. Some varieties naturally produce larger seed potatoes, while others tend to stay smaller. Because we grow many heritage and rarer varieties, the variation can sometimes be even more noticeable 📏🌱. These older varieties were often bred long before modern supermarket uniformity became the focus, so natural differences in size, shape and appearance are much more common and part of their character.
We have 70 different varieties of seed potato in 4 different net sizes and do not do any further grading to small medium and large due to space and cost.
2 Potatoes Per Pot vs 4 Potatoes Per Pot 🥔⚔️🥔
These experiments are all about space, competition and yield.
This experiment is all about space, competition and yield.
We’ve planted normal-sized, healthy, chitted seed potatoes using two different planting densities:
- 2 potatoes per pot
- 4 potatoes per pot
Everything else has been kept the same, allowing us to focus purely on how the number of plants affects growth and harvest size.
The theory sounds simple enough. Fewer plants might mean each potato has more compost, nutrients, water and room to grow — potentially producing larger potatoes. But planting more potatoes could increase the overall number harvested from each pot.
So which approach wins? 🥔🏆
Bigger potatoes with fewer plants? Or a heavier overall crop from a busier pot?
This is one of the questions home growers ask most often, especially when growing in containers or limited spaces, so we’re excited to see how the results compare later in the season.
Cut Seed Potatoes – Risky Shortcut or Smart Technique? 🔪🥔
We don’t advise this method as the tuber may not heal and could rot before it can grow.
For this experiment, we’ve cut larger seed potatoes into smaller pieces before planting. Each piece contains at one visible “eye” or sprout, giving it the potential to grow into a new plant 🌱
Now, to be clear — this is not something we normally recommend for most home growers. Cutting seed potatoes can increase the risk of rot, disease and weak growth, especially in cooler or damp conditions. 🌦️ That’s exactly why we wanted to test it for ourselves.
Interestingly, cutting seed potatoes was once very common during wartime and periods of shortage, when seed potatoes were scarce and growers needed to stretch limited supplies as far as possible ⚔️🥔. Instead of planting one whole tuber, growers would divide potatoes into several pieces to maximise the number of plants they could produce.
The big question is whether that old practice still holds up today. Will cutting potatoes allow growers to stretch their seed stock further and still achieve a worthwhile harvest — or will the reduced energy reserves and increased disease risk outweigh the benefits?
There’s only one way to find out, and we’ll be sharing the results as the season progresses 🔬🌱
We tried to get enough parts for the overall weight to be as close as possible to our control experiment.
One Chit Per Potato – Does Less Produce More? 🥔🌱
What will happen here?
For this experiment, we’ve rubbed off all the shoots from each seed potato except for one strong chit 👆🌱. Normally, a potato will produce several shoots, each capable of growing stems and eventually forming tubers underground.
The theory behind removing extra chits is that the potato can then focus all of its stored energy into one main stem rather than spreading resources across several weaker shoots ⚡🥔. Some growers believe this can lead to fewer but larger potatoes, while others argue that more stems produce a heavier overall crop.
Our expectation is that these plants may produce fewer potatoes overall, but potentially with larger average tuber sizes 📏🥔. The plants themselves may also appear less bushy above ground because they will have fewer stems competing for nutrients and light ☀️🌿.
It’s another one of those potato-growing debates where opinions vary wildly — so we’re looking forward to seeing what actually happens in real growing conditions 🔬👀.
Seed Potatoes With a Bit of Scab – Problem or Panic? 🥔
Different years will have different levels of scab.
A small amount of scab is legally permitted in certified seed potatoes and is considered a normal part of potato production 🥔. The level can vary from year to year depending on growing conditions, particularly dry weather and soil conditions during the season 🌦️. Some years produce exceptionally clean skins, while in other years light scab can be much more common across the crop. It is cosmetic and does not affect the potato’s ability to grow and produce a healthy harvest 🌱
We completely understand that some customers may feel disappointed when they receive seed potatoes with minor cosmetic marks such as scab 🥔. Because of this, we explain the grading standards, natural variation and appearance expectations both in our FAQ section and within the information tabs on each individual variety page 📖🔍. We always try to be as open and transparent as possible about what customers should realistically expect from a natural agricultural product 🌱
Another important point is that scab on a seed potato does not transfer to the next generation of potatoes 🌱🥔. Common scab mainly affects the skin appearance of the tuber and is heavily influenced by soil conditions, moisture levels and weather during the growing season 🌦️. Perfectly healthy crops will still be produced from seed potatoes showing minor scab marks, which is exactly why we wanted to include them in this experiment 🔬.
The 2025–26 season has actually seen very low levels of scab across our crops, which meant we received very few complaints about appearance this year 🥔✨. In fact, for this experiment, our staff had to work surprisingly hard to even find enough slightly scabby tubers to grow! Because of that, the potatoes used in this trial are not all the same size 📏.
While the experiment will still allow us to compare yields, the main purpose is really to demonstrate that seed potatoes with small cosmetic marks can still be perfectly healthy, vigorous and capable of producing strong crops 🌱💪.
🌱🥔✨🌱 Thousands of you grow potatoes with us every year, and together we can learn far more than any single grower ever could. Let’s compare notes, share results, and see which potato-growing myths actually stand up to a proper test. 🧪 🥔
📊 A quick note on our experiments… These are small, real-life garden trials, not lab conditions, so of course they have their limitations. Soil, weather, and growing conditions all play a part, but that’s exactly what makes them useful. They reflect what actually happens in a normal garden, not just on paper.
Looking forward to your results. We have done some small ‘tub’ tests over the years, but we do not have the space for larger trials. But there are 3 stages of potato growth which require different fertilisers. Potash is very much neglected, but essential for tuber size. I always look forward to ‘Beechgrove’ on telly for their variety trials.