Informal caregivers provide long-term, unpaid support to patients – usually family or friends – with serious illnesses. Although caregiving is essential, it can have adverse effects, e.g. physical and emotional exhaustion. Digital applications are a cost-effective alternative to manage these effects. However, applications for caregivers are usually centered on skill building and education rather than well-being, and general-purpose stress management applications – besides not specifically considering caregivers – frequently change and do not usually incorporate social aspects. To design a caregiver-centered application, we analyzed caregiver needs, specifically focusing on well-being aspects. We present Care4Plant, an application designed to measure the emotional dimension of caregivers’ burden based on the Zarit Burden Questionnaire, and suggest a set of mood improvement tasks accordingly. Care4Plant features a virtual plant that represents informal caregivers’ emotional well-being, allowing them to care for the plant through actions intended to manage their mental health and reduce stress, and to share their plant with other caregivers through a social network represented by a greenhouse. We conducted an evaluation of Care4Plant with nine users over two weeks. The results indicated good levels of usability and demonstrated that the approach of motivating users through the virtual plant was well-received.