The goal of this pilot randomised controlled trial is to test the feasibility of a brief nature-based self-help psychological intervention for low mental wellbeing. The investigators want to learn whether the intervention is likely to help improve mental wellbeing and whether it is acceptable to participants. Participants will be members of the public in the United Kingdom (UK) with low mental wellbeing and the intervention lasts for four weeks.

The main questions it aims to answer are:

Will participants' mental wellbeing improve after the intervention, relative to participants in a waiting list arm.

Will participants find the intervention useful and acceptable to do?

Participants will:

Complete baseline questionnaires on demographic information and on several areas linked to wellbeing.

Complete further questionnaires on wellbeing after 2 weeks and 4 weeks. Complete a questionnaire on their experience of the intervention at 4 weeks. Receive and complete a self-guided booklet and link to a webspace to complete activities that are informed by psychological principles.

Receive the intervention after four weeks if they were allocated to the waiting list arm first.

This study tests a brief nature-based psychological intervention for low mental wellbeing. This is a parallel groups waiting list control pilot randomised controlled trial (RCT). This a United Kingdom (UK) based pilot study and has the primary aim of assessing the acceptability and feasibility of the intervention. The pilot will assess the potential for the intervention to improve mental wellbeing but the efficacy of the intervention will be formally tested in a future powered RCT.

This RCT will compare a novel self-help guidebook called 'Roots and Shoots', which was designed to deliver a nature-based intervention for improving low wellbeing, against a waiting list control arm. Eligible participants will be randomly allocated to trial arm (1:1) using random permuted blocks, using the online randomisation service sealedenvelope.com. This is an automated process that ensures randomisation is not influenced by the researchers and prevents selection bias. At baseline (T0), 2-weeks (T1), and 4-weeks (T2) self-report assessments will be collected remotely using the online survey platform, Qualtrics®. Ethical approval was granted by the University of Exeter Psychology Ethics Committee prior to starting the study (Application ID: 5412277).

Participants will be recruited through opportunity sampling using recruitment methods including social media (e.g. Facebook, X), emails, newsletters and printed posters. Participants will be signposted to a brief screening survey in the first instance to check the eligibility criteria. Eligible participants will be contacted via email by a member of the research team to notify them of their eligibility status and confirm their availability to participate in the study. Following confirmation, participants will then be randomly assigned (1:1) to receive the intervention or be placed on a waiting list. Participants will be informed of this outcome by email. Given the nature of the intervention and study design, blinding of the participants is not possible. Participants will receive and read the participant information sheet (PIS) and provide informed consent before commencing the study. Once informed consent has been obtained, all participants will complete a series of baseline measures (T0) prior to starting the intervention or waiting list period. Following receipt of the guidebook, sent to the participant's postal address, participants assigned to the intervention group will be asked to complete the weekly activities and engage with additional online resources housed on the companion website (rowantree.uk).

All participants will be asked to complete a battery of measures at a 2-week interval (T1) and immediate post-intervention, at week 4 (T2). Participants in both the intervention and waiting list control group will complete the same set of online questionnaires at all three timepoints (T0, T1, T2), with the exception of additional feasibility and acceptability questions included in the final survey (T2) for participants in the intervention arm. All measures will be presented to participants in a fixed order and housed in the online distribution platform Qualtrics®. After completion of final survey (at 4-weeks) all participants will receive debrief information which includes the study aims, researcher contact details and signposting for further support and mental health services.

Trial Arms

The Nature-based Intervention: Roots and Shoots

The intervention, Roots and Shoots, consists of a printed, self-help guidebook that covers six main section and includes weekly, evidence-based activities, as well as additional online components. Designed as a short, four week course for improving low wellbeing, the guidebook incorporates elements of environmental psychology (e.g. forest bathing) with techniques and exercises informed by several psychological therapies and traditions. In the first section participants are provided with a comprehensive introduction to the course including nature and wellbeing psychoeducation. This is consistent with research that has highlighted the benefits of psychoeducation as an effective therapeutic approach for improving low mood in individuals with depression. The following four sections guide participants through a set of weekly activities including a habit tracker, psychological coping tool, nature contact tracker, mood and nature connection monitoring and a reflective writing exercise. The rationale for the weekly exercises was informed by behavioural activation principles, mindfulness, cultivation of habits, self-tracking of mood, nature exposure, compassion focused therapy and acceptance and commitment therapy techniques. Throughout Roots and Shoots participants will be signposted to an online webspace where they had access to additional digital resources including nature videos, meditations and breathing exercises. These activities draw on evidence showing the beneficial effects of virtual nature exposure, guided imagery, brief nature-based meditation and guided breathwork. Participants are also encouraged to reflect on their time spent engaging with nature and the guidebook activities.

Waiting list Control

Participants in the waiting list control arm will complete the assessments at the three time points: baseline (T0), at a 2-weeks (T1) and post-intervention (T2). At this point control arm participants will be offered the intervention and will receive a copy of the Roots and Shoots guidebook in the post and will be provided with full access to the additional online resources.

Analyses

Because this is a pilot RCT and is not designed to test the efficacy of the intervention, the primary focus will be on the feasibility and acceptability of the intervention. To this end the investigators will report on the feasibility of the intervention including recruitment to target, and proportion of participants returning the assessment surveys. The investigators will report the simple descriptive statistics on the feasibility and acceptability questions, as well as for the psychometric measures. In the analysis the investigators will follow the principle of intention to treat (ITT). That is, the investigators will not excluding any participants based on their level of engagement with the intervention. The investigators do not plan to remove outliers from any analysis.

The investigators will report the relative change in mean scores on the primary and secondary outcomes. The investigators will primarily report on mean differences, effect sizes and confidence intervals, not p-values. The investigators therefore will not be applying correction for multiple comparisons. No power calculation is required for this pilot study. The investigators will report means, standard deviations and 95% confidence intervals for the psychometric measures and report Hedge's g for estimates of effect size. To assist in the design of a potential future fully powered RCT, the investigators will carry out supplementary analyses. The investigators will carry out repeated measures analyses on the outcomes using mixed models or a general linear model. The investigators will also calculate Clinically Significant Change (CSC) to help assess the clinical significance of any improvement measured in the outcomes. The investigators will explore any clinical change on outcomes using graphs.

Inclusion Criteria:

• Participants must score 22 or less on the SWEMWBS scale-indicating low wellbeing-to facilitate clearer assessment of the intervention's consequence on such a measure.
• Participants must be 18+ to take part in the study,
• Participants must have sufficient understanding of the English language, to be able to fully comprehend the measures and intervention tasks, which at present are limited in translation due to methodological constraints.

Exclusion Criteria:

• Visual or auditory impairments that may impede full engagement with the intervention.
• Receiving formal psychological therapy in the last three months.

Outcomes are recorded remotely by the participant, online using the Qualtrics platform.