By this time, we were starting to get excited and anecdotal evidence of the benefits of volcanic rock dust were coming in, not only from gardeners but also from dairy farmers and fruit farmers. By the start of 2025 we had a discovered a source of locally ‘grown’ rock dust from Cursiter Quarry just outside Kirkwall, giving a much more sustainable and economical option that didn’t have to be shipped over from the Scottish mainland.

We decided to try growing carrots in both the original volcanic dust and the Orkney quarry rock dust and opened the trials up to a wider group of growers both on the mainland and the islands. We had a fantastic response and couldn’t wait for the results of our 2025 blind tasting session at the Science Festival. To our great satisfaction, the carrots grown with the Orkney rock dust grew better, gave a bigger crop and tasted better than both the carrots grown in normal soil and the carrots grown with volcanic rock dust. I am now totally converted to the benefits of Orkney rock dust!

This year we have decided to go back to our roots and run a trial growing potatoes, just as we did back in 2023, but this time we are going to focus solely on improving the soil with Orkney rock dust rather than the volcanic rock dust.

What better crop to test our rock dust than the good old tattie? In our household we must eat potatoes at least four times a week, and who doesn’t love a bag of chips or a steaming pile of buttery mash! We have already reached out to a handful of growers who are going to provide the potatoes for our blind tastings in September, but we have space for up to ten more growers to join in.

If you are interested to find out more, contact us at info@sufficientorkneyfood.co.uk. Essentially all you will need is 10–20 potato tubers and a patch of ground (or a couple of big pots) to grow them in, and we will provide you with some rock dust and a form for reporting the outcomes.

We recommend applying 1kg of rock dust per square metre of ground and either fork it in prior to planting your tubers or rake it into the top few inches of soil as a top dressing if your potatoes are already in the ground. Of course, only add the rock dust to half of your crop if you want to see the difference in growth and make sure you label which plants are grown with and which ones without! You can use any variety of potatoes you wish, and any techniques you find have worked in the past. We’d love to hear how you get on and please do come along to the blind tasting session in UHI Orkney’s Overblikk Restaurant in September.

Over the years I’ve grown potatoes in just about every way possible, but the older I get, the simpler the process I use. I used to spend hours digging a perfect trench, lining it with newspaper and back-filling it with compost before carefully planting my precious tatties. Nowadays, I just plant them straight into the ground, about 20cm deep with a trowel, just as if I were planting a tulip bulb. I see it as being efficient rather than lazy, but I have the advantage of gardening on light and sandy Moray soil! The magic of potatoes if that they do a wonderful job of breaking up the soil themselves without the need of digging prior to planting. My rule is to feed my whole plot with a mulch of garden compost or manure through the winter, another reason why I don’t bother digging trenches.

I plant first and second earlies about 30cm apart and maincrops 50cm apart in single rows if I have the space, or staggered double rows if I’m on a small plot. Late March to the end of April seems about right to miss the frosts, but I’m always ready with a roll of fleece on chillier nights. It takes 3 or 4 weeks for the first leaves to show through the soil (usually longer than you think if you’re as impatient as I am!)

I find a top dressing of blood, fish and bone works wonders for potatoes, they’re a hungry crop. I tend to mound them up as soon as the leaves appear, to a height of about 30cm, giving lots of extra room for tubers to grow from the stems of the plants.

In the first couple of months of growing, I only water my potatoes in very dry weather. If you give them too much water before the new tubers start to form, you’ll end up with ‘all top and no bottom’. As soon as the first tiny tubers start to form, I’ll water as often as possible to help them swell up. For new potatoes, I know when it is time to start digging them up when the flowers go over, but I try to leave the plants for as long as possible for a big crop to store over the winter. I’ll occasionally boost my plants with a liquid feed from mid-summer onwards. Being in a generally dry and windy garden means that early blight isn’t often a problem for me, but in wet years I’ll cut back the holms right to the ground as soon as there is any sign of it and get my tatties lifted as soon as possible.

My favourite variety has to be Charlotte, but I always grow Maris Piper, Desiree and Cara. For this year’s trial I am growing Red Duke of York because it tends to be very reliable in my soil and it seems that red skinned varieties are less susceptible to slug attack. I’m also trying out Caledonia Pearl for the first time this year.

I can’t wait to see the results of this latest round of trials. Research into this field of horticulture is still in its infancy but there has been huge progress in our understanding of soil science in recent years. Far from being a sterile medium in which our plants are anchored, the soil is teaming with life, a vast biome full of organisms that are vitally important to our plants and our own health. I suspect that incorporating rock dust not only adds vital trace elements to the soil, but the mineral content also helps to feed the fungal mycelium that then performs an essential role in feeding the roots of plants. Now, more than ever, taking responsibility for our own food security is incredibly important and the first step to growing your own healthy, nutrient rich food is to care for the soil. So, watch this space for more updates on the rock dust trials and happy growing!