This September, the Colour in the Margins Team were joined by staff from Kew’s Millennium Seed Bank and a group of eager volunteers at the Cholderton Estate in Wiltshire.

Our objective for the day was to collect seed from a population of Red Hemp-nettle (Galeopsis angustifolia) on the estate, which would subsequently be used towards the local conservation of the species. Cholderton Estate is roughly 1,000 Ha and is owned by Henry Edmunds, a landowner with a passion for organic farming and conservation.

Red Hemp-nettle has declined dramatically in the last 60 years, and is now listed as critically endangered. It can be found across a handful of farmland sites in the Wessex area, including at Cholderton, where it grows on a fallow plot designed for ground-nesting birds.
Aside from providing a suitable nesting habitat for farmland birds, plots like these can often be a haven for rare arable plant species, and the plot at Cholderton also supports Narrow-fruited Cornsalad, Field Gromwell and Rough Poppy.
Henry ensures that the plot is managed beneficially for Red Hemp-nettle and a range of other species by cultivating it in spring and keeping disturbance of the site to a minimum throughout the summer months. The estate’s organic status ensures that this area does not receive any fertilisers or herbicides, which have contributed to the species’ decline in recent years.

With the weather conspiring against us and the rain lashing down, we began the day’s proceedings by assessing the site for suitability to collect seed. In order for the collection to be possible, we had to ensure that the population was large enough, and that a big enough proportion of this population were currently in seed.

A quick count revealed over 500 individual plants. Each individual plant has several calyxes – cup-like structures that house the plant’s seeds. Each calyx can potentially contain up to four seeds. Steph Miles and her colleagues from the MSB explained to the group how to use these factors to determine whether seed collection should be undertaken, and after some thorough calculations, it was decided we could sustainably collect roughly 1,600 seeds. This was around 20% of the total number of plants with harvestable seeds, ensuring that some seed is allowed to fall and germinate naturally. You can find out more about the MSB’s seed collection here.

Making the best of a short break in the weather, we split up and set about collecting seed. In order to avoid over-collecting, we formed lines and worked methodically; carefully removing the calyxes that housed mature, black seed and leaving those that weren’t quite fully developed. From the calculations we did before beginning the collection, we knew that if each of the people present collected 50 calyxes, we would meet our target of seed required. As the seeds were gathered in, they were placed in breathable cloth bags to allow any moisture to escape. It’s important to do this as seeds will last longer once dried, and they could become unusable if stored in an environment that does not allow water to dissipate.

Before long, we had accumulated enough seed, and we reconvened to label up our samples and return to warmth of our cars. The seed we collected will now be stored and curated by the staff at the MSB in Wakehurst until it is needed by the CitM Project. The project is working closely with a handful of landowners to reintroduce Red Hemp-nettle to sites where it has disappeared.

If you are interested in finding out more about how the Colour in the Margins project is working for arable wildlife in Wessex, please contact Rob Blackler at or on 07834792856. Equally, you can visit our website at:


Robert Blackler

Project officer



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