By Dr Philip Burgess


Over many seasons, the average optimum time to plant potatoes, in Scotland, seems to sit around April 20 – almost exactly a month from when you are reading this.

But this simplifies farming to growing by a calendar and we all know that’s usually the wrong approach. It’s more important to plant tatties, when the conditions are right.

Soils should be warm, perhaps 7°C, and rising. At these temperatures, the sprout can grow fast and emerge quickly. In cold soils, which are often also wet, the seed tuber sits there and does nothing. Meanwhile, rhizoctonia and other pathogens can begin to take advantage.

The soil also needs to be cultivated correctly to get the seed tuber into a comfortable position from where it can grow quickly and without any restrictions. When you first get the machinery out into the field, look very critically at what you are doing.

Those early planted crops may statistically yield well, but not if you damage the soil structure by smearing the ridge bottom and causing compaction. The damage done by even slight compaction will far outweigh any small advantage of planting early.

In my experience, with most varieties, yield is not significantly reduced until planting in the second half of May. So, be patient and wait until the conditions are right for each and every field.

But you can also look at the set up in the field, there has been excellent research funded by AHDB, that demonstrated the significant advantages that can be had by cultivating a little shallower.

You can work the field when otherwise you would be causing compaction; you will use less fuel; you might travel quicker across the field; and the final yield will be the same or perhaps slightly higher.

All things worth bearing in mind when you’re in the thick of planting. Obviously, it is important not to plant too shallow, but in many situations, there is room to be just a cm or two shallower, which is enough to make a difference.

Bed tilling has been shown too often not be necessary and rarely does it speed destoning. It may lead to a very fine seedbed, which might look great, but isn’t the most resilient ridge if the weather turns bad.

So, keep the bed tiller in reserve. If you need to use it, then you’re possibly growing your potatoes in the wrong fields. It’s a bit late to do much about it this year, but an important lesson as you look ahead to 2021.

In the longer term, the health and condition of your soil is going to determine your ability to produce potatoes and other crops profitably. Higher organic matter content soils are more productive and resilient. The number of days on which these fields can be worked increases as the organic matter increases.

Fortunately, in Scotland, organic matters are not at the rock bottom found in some other parts of GB, or abroad. But it’s an advantage worth preserving, especially as we see more extreme weather events, wetter winters and perhaps drier summers.

So, the optimum time to plant tatties depends upon not just the calendar, but on your ability to manage the entire operation in the field. Looking forward over the entire rotation, you need to look after your soils to make things easier in the future.