Proving the Work: Drone Canopy Penetration Trial at Silverhand Estate
Updated: Sep 6
The brief from Silverhand Estate was simple, and the kind we like: prove it before we commit.
Silverhand Estate, near Luddesdown in the Kent Downs, is one of England's most ambitious organic vineyards — 300 hectares of vines across Kent, Essex and Sussex, managed to B Corp standards without synthetic inputs. With vines trained at 1.6 and 2.2-metre row spacings, the canopy at full development is dense and layered. The question they put to us wasn't whether drones could spray — it was whether the spray would actually reach where it needed to go.
An efficacy trial before any product goes down
The most responsible way to introduce drone application to any new site is with an efficacy trial, using water before any product is ever loaded into the tank. The principle is straightforward. Spray water across representative rows under working conditions, then check where it landed.
For vineyard nutrition and foliar feeding work, penetration into the mid and lower canopy is what matters. A spray that coats the top leaves and leaves the bunch zone dry hasn't done the job. We needed to demonstrate coverage at canopy depth, not just across the surface.
We arrived on site at 7:00 am. Early enough to work before the day's thermals built up, and to give the vines still air conditions that help the rotor downwash push spray deeper into the foliage.
How we ran it
The trial ran across a section of established vines at two application rates: 150 litres per hectare and 250 litres per hectare. Running multiple rates in a single trial session lets both parties see the effect of volume on coverage without repeating the day.
The XAG P100 Pro flew at consistent height above the canopy, close enough for the rotor downwash to work, far enough to allow the spray cone to open before it hit the top leaves. Flight speed was kept low on each pass. At low forward speed, the rotors push more air downward per metre of travel, which drives spray through the upper leaf layer and into the canopy interior.
Water-sensitive indicator cards were placed at three positions in the canopy — top, mid, and lower — across multiple rows, including rows tested at each application rate. After each pass we collected and assessed the cards.
What the results showed
At 150 litres per hectare, top-canopy coverage was strong and mid-canopy coverage was measurable and consistent. At 250 litres per hectare, the improvement into the lower canopy was clear: coverage became even across all three depth positions, with no dry zones in the areas we tested.
Research into drone spray efficacy in vines identifies a target of 20–30 droplet impacts per square centimetre for foliar nutrition work, with good distribution across canopy depths. Our cards at 250 L/ha hit that range from top to lower canopy. The coefficient of variation, a measure of how evenly the spray was distributed between test positions, came in below 20%, which is the accepted benchmark for consistent application.
For Silverhand's team, seeing the cards from the interior of the canopy told them what they needed to know. The spray had got there. The trial showed that with the right flight parameters, drone-applied foliar nutrition is a realistic option for their operation.
What this opens up
For a 300-hectare organic vineyard, the ability to apply foliar feeds, trace elements and liquid nutrition without ground machinery is significant. Ground passes on tight 1.6-metre rows at full canopy require highly skilled operators, narrow equipment, and dry soil conditions. A drone pass requires none of those constraints.
The efficacy trial de-risks the step from "can it work here?" to "when do we start?" Silverhand were happy with what they saw, and so were we.
Interested in a trial on your vineyard?
If you manage vines in the South West or South East and want to know whether drone application would work for your site and row spacing, a water efficacy trial is the right starting point. It costs nothing in product, takes half a morning, and gives you cards in your hand rather than a sales pitch.
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