Giant Hogweed Surveys with a Smartphone

For an overview of the whole survey strategy see this presentation

When surveying, we:

  • Record all the plants we find using a GPS app on a smartphone, as waypoints
  • Record where we have & haven't surveyed, ideally as a Track
  • Export them all & email to the map coordinator, who transfers them onto the master map

When to Survey

Ideally we survey at least three times, around April, again late May/early June, and lastly in July.

On the Tyne and Esk we have a full set of sightings from last year, and plants usually appear in the same places, but often elsewhere too. So the early survey is still very useful to the farmers; and is also vital for our annual statistics. The later one in early Summer will spot any new plants that have grown, so the farmers can spray again. The final one is vital to spot any plants which have escaped attention - as by now they will certainly be flowering, if not worse, in seed. Or if hopefully there are none, so we can confidently place a green tick on the map!

How to Recognise

You need to become familiar with what the plant looks like, whether its young or mature - hopefully you will never see a flowering one, but vital to recognise if you do!  Useful guides are this NNSS Leaflet or the WildFoodUK website. Note that it's very easy to confuse with the much more Common Hogweed, even other Umbellifers. And you also want to be able to identify Japanese Knotweed. Read these and then test yourself with our Quiz - which has easy, medium and hard questions!

What to Record

We want to record all the details we can, to help the farmer find them (and for survey monitoring):

  • Plant
    • GH for Giant Hogweed
    • JK for Japanese Knotweed
    • HB for Himalayan Balsam
  • Quantity
    • eg x5
    • For JK/HB estimate the area, eg 20sqm
  • Status
    • eg small, medium, large, flowering (hopefully not!)
  • Bank
    • Which side of the river its on, eg South Bank
  • Other Useful Info (if long, put in Notes)
    • Under Tree; Hidden in bushes; opposite gate
    • looks sprayed
    • still not been treated despite 2 previous reports
    • Dead, but has full seed head - must have been missed last year
  • Your Name
    • Add your name/initials, eg DaveQu
  • Timestamp
    • Date & Time get automatically recorded & exported by the software


  • GH x5 3ft North Bank hidden in willows. DaveQu
  • GH x1 flowering 10m off West bank in woods. Still there although reported in April! DQ
  • JK 30sqm island by West Bank. Look as if sprayed. daveq
  • Didnt survey 20m upstream of here, too overgrown. DQ
  • Started/Ended my Spring survey here. Dave Qu


  • It is important to record on which side it is of any un-crossable barrier, like the river, or a railway, or road, as this is key for anyone planning to treat it, especially as it's often a different landowner.
  • Recording where you start and finish a survey helps us track where has been checked. Even better is to record a Track, which is simple to do with the Gaia app.
  • If there's a section you just can't see well enough to survey, please record that as a waypoint too, so we know where hasn't been checked. This could be overcome by scouting from the opposite river bank, or entering the water with waders, which a couple of us have.
  • If you spot a plant you have reported before (this year), please do report it again, and indicate this. It means no one has yet dealt with it, so will prompt us into further action (and means more accurate stats).
  • Adding your name/initials can be helpful later if there are queries

The App

We use a free app called Gaia. This is available on both Android and iPhones, although they look slightly different - screenshots below show both (Android first). NB: If you have Motion-GPX installed on your iPhone, or GPS-Navigator on Android, the instructions are here, but we recoomend you switch to Gaia.

Detailed Instructions:

Install & Configure Gaia

  • Tap on the Play Store/App Store
  • Search for the app called Gaia-GPS, and install it
  • Wait a couple of minutes until you can tap Get Started
  • Activities : We're not interested in activities - just tap Next
  • Account: Create an account using an email address of your choice
  • Location: tap Sounds Good, the While using.. option if offered, and Sounds Good again
  • Then agree to the Disclaimer
  • It now shows the map, but its San Jose!
  • Tap the Crosshairs icon, and it centres on where you are
  • Pinch to zoom right in

We normally use only these icons:

Record  a Survey (Track)
    Locate  - crosshairs to centre on and follow yourself
     Add     - Add a waypoint, etc
    Map     - (Guess)
   Saved   - View your saved tracks, waypoints, etc

There is a full description of the main screen on the Gaia support website here: Using-the-Main-Map

A couple of settings are worth changing from the default:

  • The labels you create for waypoints aren't displayed, so tap the Layers icon top right, look for the Waypoint Labels option (under Map Overlay on IOS) and switch it on
  • The top of the map shows a dynamic compass, which personally I don't find useful, and it drains the battery, so in Settings/Map Controls I switch it off

Conducting a Survey

On the survey, you ideally record a Track, which plots the route you cover, but you definitely record a Waypoint for each plant you spot. Waypoints are attached to the track, and so are automatically included in an export/email of the Track.


  • In the iPhone version there's currently a bug with exporting a Track, so we also create a folder, and export that instead, which includes the Track and all its waypoints. We'll update here once we know the bug is fixed.
  • Before you start a survey, make sure the phone is fully charged up, because GPS drains the battery fast
  • NB: buttons currently show only Android screens, not iPhone


We strongly recommend you practice this before you do it for real

  • Outside, e.g. in the garden, so GPS works
  • Email us your test results, and we'll give you feedback
  • Hide or delete your practice afterward (using Saved)

When You're Ready to Start

  • Tap the Map icon if its not displaying
  • Tap the Locate icon to centre on yourself
  • If you have surveyed before, view/hide those sightings, using Saved, Show on Map/
  • Tap Record - this creates a track highlighting your route (so no need to waypoint Start/End of survey)

When you find a plant

  • Tap the Add icon
  • If its nearby, select Add Waypoint (My Location)
  • But if it's some distance away, eg the other side of the river
    • Select Add Waypoint
    • Drag it to the best position you can
  •   Enter its details = see above
  • On an iPhone, if this is the first waypoint, change the folder
    • Under Add to a Folder tap the existing folder (it may be Choose Folder) & tap Change Folder
    • Tap  and create a new folder
    • Tap the folder, which assigns it
    • All items created from now on will be stored in this folder, until you change the folder (this includes the Track)
  • Save
  • You can pause & resume the Track - maybe you want a sandwich!


When You've Finished the Survey

Complete the survey details and email us the Track with its Waypoints:

  • Tap the Recording button and Finish Track
  • On Android, Tap Add notes here (or pen) and tell us about the survey (+ your name)
  • On an iPhone [screenshot]
    • Tap the folder & View Folder
    • Open Notes in IOS folder & tell us about the survey (+ your name)
    • Tap   to get the folder menu
  • Select Export, then KML (better than GPX for several reasons)
  • Tap your preferred email program, eg Google Mail
    • Enter the email address
      • Either
      • or EskHogweed if you're on the river Esk
    • Enter any relevant info in the email body
  • And then Send it
  • In a day or so it all gets transferred onto the master map

Housekeeping (you may ignore this section!)

To view, edit, export or delete any of your items, Tracks and Waypoints, tap Saved

  • (top right)
    • Android: Hide/Show Filed Items (i.e. allocated to a Folder)
    • IOS: Create Folder & change List settings
  • Tap All to filter the list, eg to show only Tracks (it remembers this choice)

Tap on a Track

Options are divided between the menus, the pen  and the action icon

Useful actions are:

  • Eye - toggles whether it's visible on the map
  • Export  -  if you want to email it
  • Delete   - You may have to scroll up to see this option
  • Edit/Crop  - to trim the ends off a Track, eg if you forgot to Finish it
  • Change Colour   -  on Android, need to tap the track's thumbnail
  • Resume Recording  - eg to continue a survey that you didn't complete

Tap on a Waypoint (having changed the filter)

  • Edit/Reposition/Move - The Waypoint is circled and you can drag it to a new position

You can also reach the above menu options from the map by tapping on the item & then tap

You can also import an exported file using Map/Add/Import, eg this one Demo Track from the above screenshots (which needs unzipping)

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