A handheld device for determining a status of a plant comprising: - a multi pixel digital colour sensor, configured for obtaining a colour image of a part of the plant which status is to be determined, comprising at least a red, green and blue colour component, together forming a set of colour components; - a light source arranged for providing broadband illumination, wherein the light source and the multi pixel digital colour sensor are arranged in substantially the same plane; - a light guide for guiding the light from said light source into the direction of the multi pixel digital colour sensor; - an open sample space in contact with ambient air and ambient light, provided between the multi pixel digital colour sensor and a light-emitting surface of the light guide, for insertion of at least a part of the plant which status is to be determined, therein; - a processing unit configured for controlling at least the multi pixel digital colour sensor and the light source, characterised in that the processing unit is configured for: - switching the light source on and off, - obtaining a first image of the part of the plant with the multi pixel digital colour sensor with the light source switched on and transmitting broadband illumination using the light guide through the part of the plant into the multi pixel digital colour sensor, - obtaining a second image of the part of the plant with the multi pixel digital colour sensor, with the light source switched off and not illuminating the part of the plant, (i) determining a first colour value representative of a difference in intensity values in the first and the second image for a first of the colour components, (ii) determining a second colour value representative of a difference in intensity values in the first and the second image for a second of the colour components, (iii) calculating a value representative of a status of the plant using the first colour value and the second colour value. - a multi pixel digital colour sensor, configured for obtaining a colour image of a part of the plant which status is to be determined, comprising at least a red, green and blue colour component, together forming a set of colour components; - a light source arranged for providing broadband illumination, wherein the light source and the multi pixel digital colour sensor are arranged in substantially the same plane; - a light guide for guiding the light from said light source into the direction of the multi pixel digital colour sensor; - an open sample space in contact with ambient air and ambient light, provided between the multi pixel digital colour sensor and a light-emitting surface of the light guide, for insertion of at least a part of the plant which status is to be determined, therein; - a processing unit configured for controlling at least the multi pixel digital colour sensor and the light source, - switching the light source on and off, - obtaining a first image of the part of the plant with the multi pixel digital colour sensor with the light source switched on and transmitting broadband illumination using the light guide through the part of the plant into the multi pixel digital colour sensor, - obtaining a second image of the part of the plant with the multi pixel digital colour sensor, with the light source switched off and not illuminating the part of the plant, (i) determining a first colour value representative of a difference in intensity values in the first and the second image for a first of the colour components, (ii) determining a second colour value representative of a difference in intensity values in the first and the second image for a second of the colour components, (iii) calculating a value representative of a status of the plant using the first colour value and the second colour value. (i) determining a first colour value representative of a difference in intensity values in the first and the second image for a first of the colour components, (ii) determining a second colour value representative of a difference in intensity values in the first and the second image for a second of the colour components, (iii) calculating a value representative of a status of the plant using the first colour value and the second colour value.