Weed Identification Apps: A Practical Guide

A weed identification app names a weed from a photo. You photograph the plant you are unsure about, the app matches it against reference images of known weeds, and the likely name comes back. The ones worth using go past the name and tell you whether the weed matters where you live and what you can do about it. Pocket Gardener works this way: upload a photo of the weed and the answer arrives with context for your region and control options where that guidance is available. It runs in a web browser on a phone or a computer, so there is nothing to install.

Why weeds need their own answer

Naming a weed and naming a garden plant are two different jobs. With a garden plant you usually want the name so you know how to look after it. With a weed you want to know whether to act, how soon, and what the least drastic way of dealing with it is. An app built for weeds answers that second question instead of stopping at the name.

In Pocket Gardener the photo goes down a dedicated weed path rather than the standard plant identification one. That is why the answer comes back with control information beside the name: the likely weed, the context that matters where you are, its likely distribution, practical notes on the trouble it causes, and prevention along with cultural, mechanical and chemical control options where that guidance is available.

What to look at before you take the photo

The app does the matching, but noticing a few features yourself is what lets you tell a good answer from a near miss.

• The leaves. Their shape, whether the edges are smooth or toothed, and whether they sit opposite each other on the stem or alternate along it.
• Flowers or seed heads. Most weeds are easiest to name once they flower, and the seed head is the part that decides how urgent the job is.
• How it spreads. One plant on a single taproot is a different problem from one running sideways or coming up from the roots across a patch.
• The stems. Hollow or solid, smooth, hairy or prickly, and whether a milky sap shows where something has been broken off.
• How much of it there is. One plant in a bed, a strip along a fence, or most of the lawn.
• Where it is growing. Sun or shade, wet or dry, bare soil or thick planting, and whether it turned up this season or has been there for years.

Taking a photo the app can read

• Get in close enough that a leaf fills a good part of the frame, then take one more from a step back showing the whole plant.
• Shoot in daylight with the sun behind you rather than behind the plant, and skip the flash.
• Include the flower or the seed head if the plant has one, because those narrow things down quickly.
• Photograph the base of the plant where it meets the soil. Runners, rosettes and creeping stems show up there.
• Hold still until the picture is sharp. A blurry photo leaves the match guessing.
• A photo already on your phone is fine, so a weed you noticed last week can still be identified.

Reading the result

Any app will give you a name. What makes the answer worth acting on is what comes with it: whether the weed is likely to be found where you live, what trouble it causes, and more than one way of dealing with it, so you can choose an approach that suits your garden rather than reaching straight for a spray.

Then check the name against the features you noticed. If the suggested weed has a hollow stem and yours is solid, it is the wrong plant however confident the answer sounds. When you are not sure you are looking at a weed at all, run the same photo through plant identification as well and compare the two answers before you pull anything out.

Weeds and where you live

A weed is only a weed in a place. The same plant can sit on a nursery bench in one state and be a declared problem in another, so where you are changes what you should do about it.

• Local councils publish weed lists for their own area, which is the quickest way to find out whether what you have is one they want gone.
• States and territories declare some weeds, and the rules set out what a landholder has to do about them. Those duties are worth reading before you decide to leave something where it is.
• Botanic gardens, garden clubs and local nurseries will usually look at a photo or a cutting and tell you what it is.
• When you search a name, add your state or your region. Common names move around the country, so the botanical name is the one worth writing down.

Acting on the name

Most weeds are easier to deal with before they set seed, so the seed head is the thing to watch. Pulling a plant while the soil is damp brings the roots with it more often than pulling it dry. Bare soil is where the next one starts, so filling the gap with planting or mulch saves you doing the same job twice.

Treat anything you cannot name as unknown until you can. Do not eat it, wear gloves while you are pulling it out, and wash your hands afterwards, because a few common weeds irritate skin.

The name is the start of the job rather than the end of it. What you really want to know is whether the plant matters where you are standing, and what it takes to be rid of it.

Trying it on the weeds in front of you

The Free plan costs nothing, runs for 14 days and needs no card. It includes three weed identifications, so you can photograph the weeds you are fighting now and read what comes back, control information included, before you pay for anything. You keep everything you made when the 14 days are up, and the plans are set out on the home page.