Weed back isn’t something you get after a gone-wrong festival experience. No, it’s an infamous condition that afflicts green-fingered sorts on a constant mission to banish weeds from their otherwise perfect patches. Tertill (US$199, Kickstarter) doesn’t get weed back. It gets weeds back. With a string strimmer. Solar-powered and autonomous, this little green ‘bot rolls around your garden in search of anything small enough to fit under its rim. Anything that does is, as far as Tertill is concerned, game for a whacking. That means you’ll need to protect saplings with mesh (if it bumps into something tall enough it’ll turn away) - but you can also rest easy knowing Tertill’s on four-wheel-drive weed patrol.