Horticultural therapy program for improving emotional well-being of elementary school students: an observational study

The intervention was a structured **horticultural therapy program** consisting of seven weekly sessions, each lasting 60 minutes. Activities included planting seeds, transplanting seedlings, making flower arrangements, growing vegetables, and harvesting produce. The program was delivered during regular school hours or after-school classes.

There was **no comparator group** — this was a single-group pre-post observational study. Every student received the program.

The outcome measures were:

**Emotional intelligence** (ability to recognize, understand, and manage one's own emotions and those of others)

**Resilience** (ability to bounce back from adversity)

**Self-efficacy** (belief in one's ability to succeed in specific situations)

These were measured using validated Korean-language questionnaires before and after the 7-week program. Students also completed a satisfaction survey at the end.

**582 elementary school students** in South Korea

Age range: 11–13 years old (grades 5–6)

Recruited from **28 different schools**

Gender split: approximately equal (51.5% male, 48.5% female — exact numbers: 300 boys, 282 girls)

No exclusion criteria reported (all students who volunteered from participating schools were included)

Setting: regular school classrooms or after-school programs, not a clinical or laboratory environment

Three validated Korean-language questionnaires were used:

1. **Emotional Intelligence Scale** — developed by Moon (1996) for Korean children. Measures four sub-domains: emotional perception, emotional expression, emotional empathy, and emotional regulation. Total score range not explicitly stated, but higher scores indicate better emotional intelligence.

2. **Resilience Scale** — developed by Joo (2008) for Korean youth. Measures ability to cope with stress and adversity. Again, higher scores = better resilience.

3. **Self-Efficacy Scale** — developed by Kim (2004) for Korean students. Measures confidence in one's ability to perform tasks and achieve goals. Higher scores = greater self-efficacy.

All questionnaires were self-reported by the students (paper-and-pencil format), administered in the classroom before the first session and after the final session.

A **program satisfaction survey** was also given at the end, asking students to rate their enjoyment, interest, and willingness to participate again on a 5-point Likert scale.

**Study design:** Single-group pre-post observational study. This is the weakest design for establishing cause-and-effect because there is no control group, no random assignment, and no blinding.

**Randomisation:** None. All students received the program. There was no comparison group (e.g., students who did not do gardening, or who did a different activity).

**Blinding:** None. Students knew they were participating in a gardening program. Teachers knew the program was happening. Researchers knew which students were in the study. The outcome assessors (students themselves) were not blinded — they filled out questionnaires knowing they had just completed a gardening program.

**Duration:** 7 weeks total, with one 60-minute session per week. That's 7 hours of total intervention time. Pre-test was given in the week before session 1; post-test was given in the week after session 7.

**Statistical approach:** Paired t-tests (comparing pre vs. post scores within the same group) and independent t-tests (comparing boys vs. girls). They also reported effect sizes (Cohen's d) for some comparisons. Significance was set at p < 0.05.

**What this design can prove:**

That scores changed from before to after the program

That boys and girls showed different patterns of change

That students reported high satisfaction with the program

**What this design cannot prove:**

That the horticultural therapy *caused* the changes. Without a control group, any number of other factors could explain the improvements: natural maturation over 7 weeks, the Hawthorne effect (students feeling special because they're in a study), the novelty of any new activity, regression to the mean, or simply the passage of time.

That gardening is better than any other group activity (e.g., art, music, sports) for emotional well-being

That the effects lasted beyond the 7-week program (no follow-up was conducted)

**Major methodological weaknesses:**

No control group — this is the most critical flaw

No blinding at any level

Self-report questionnaires only (no behavioral observations, teacher reports, or physiological measures)

Short duration (7 weeks, 7 total hours)

No follow-up to see if effects persisted

Potential for demand characteristics (students may have answered what they thought researchers wanted to hear)

The same questionnaire was used twice only 7 weeks apart — practice effects could inflate post-test scores

**Primary outcome — Emotional Intelligence:**

Overall, emotional intelligence scores increased significantly from pre to post (p = 0.003)

Effect size (Cohen's d) = 0.13, which is considered a **small** effect

Both boys and girls showed significant improvements when analyzed separately (p values not reported for subgroups, but authors state "emotional intelligence improved both male and female students")

**Secondary outcomes — Resilience:**

For the whole group, resilience scores did **not** change significantly (p value not reported, but authors state no overall effect)

When broken down by gender: **boys** showed a significant increase in resilience (p = 0.001, Cohen's d = 0.20 — small effect)

**Girls** showed no significant change in resilience

**Secondary outcomes — Self-efficacy:**

For the whole group, self-efficacy scores did **not** change significantly

When broken down by gender: **boys** showed a significant increase in self-efficacy (p = 0.001, Cohen's d = 0.20 — small effect)

**Girls** showed no significant change in self-efficacy

**Program satisfaction:**

94.7% of students rated the program as "satisfied" or "very satisfied" (4 or 5 on a 5-point scale)

No specific breakdown by gender reported for satisfaction

**Gender differences summary:**

Boys improved on all three measures (emotional intelligence, resilience, self-efficacy)

Girls improved only on emotional intelligence

The authors speculate this might be because boys are less emotionally expressive in Korean culture and thus had more room to grow, or because the physical/outdoor nature of gardening appeals more to boys — but these are post-hoc explanations, not tested hypotheses

The effects were **small** by conventional standards:

Emotional intelligence improved by about 0.13 standard deviations overall — this is roughly the equivalent of moving from the 50th percentile to the 55th percentile

For boys, resilience and self-efficacy each improved by about 0.20 standard deviations — moving from the 50th to the 58th percentile

To put this in perspective: a typical educational intervention (e.g., extra tutoring) might produce effect sizes of 0.3–0.5. A well-designed mindfulness program for children might produce effect sizes of 0.2–0.4. So these effects are on the lower end of what's considered meaningful.

The absolute changes in raw scores are not reported in the abstract or results section in a way that allows translation to "X points on a scale." The authors only report p-values and Cohen's d effect sizes.

**Acknowledged by authors:**

No control group — they explicitly state this limits causal inference

Short program duration (7 weeks)

No long-term follow-up

Possible gender differences need further investigation

The program was conducted in a school setting, which may limit generalizability to other contexts

**Additional limitations a critical reader would note:**

**No control for the Hawthorne effect:** Students knew they were in a special program. Any novel, engaging activity might have produced similar results.

**Self-report bias:** Children aged 11–13 may not be reliable self-reporters of emotional constructs, especially when they know they're supposed to have benefited from a program.

**Practice effects:** Taking the same questionnaire twice in 7 weeks can inflate scores simply because students remember the questions.

**No blinding of teachers or researchers:** Teachers who facilitated the program may have inadvertently encouraged positive responses.

**No active control:** Even a control group doing a different structured activity (e.g., art class, sports) would have been far more informative.

**Multiple comparisons:** They tested three outcomes (emotional intelligence, resilience, self-efficacy) plus gender subgroups — that's at least 6 statistical tests. They did not adjust for multiple comparisons (e.g., Bonferroni correction), which increases the risk of false positives.

**Effect sizes are small:** Cohen's d of 0.13–0.20 is considered "small" and may not be practically meaningful for an individual child.

**No information on dropouts:** They started with 582 students, but we don't know if all completed the program and both questionnaires. Attrition could bias results.

**Cultural specificity:** Korean educational culture is highly structured and exam-focused. Results may not generalize to other countries or school systems.

**No dose-response analysis:** They didn't test whether students who attended more sessions showed greater improvements.

**No objective measures:** No behavioral observations, teacher ratings, academic performance data, or physiological stress markers (e.g., cortisol).

For someone running their own n=1 experiment (or a small group experiment):

### What to test (specific intervention and dose)

**Intervention:** Structured horticultural therapy — planting, transplanting, watering, weeding, harvesting, and flower arranging. The key is hands-on contact with plants and soil, not just being outdoors.

**Dose:** 7 sessions, 60 minutes each, once per week (7 hours total). This is a reasonable starting point, but based on the small effects, you might want to try a longer program (e.g., 12 weeks) or more frequent sessions (2–3 times per week).

**Alternative dose to test:** 20–30 minutes of daily gardening (e.g., tending a small container garden) vs. one longer weekly session. Daily micro-doses might produce larger effects.

### Minimum meaningful duration

At least 7 weeks (based on this study). However, since effects were small, consider **12 weeks** as a more robust minimum. Emotional changes take time to develop.

If you're testing a single session (e.g., "Does 60 minutes of gardening improve my mood today?"), measure immediately before and after that session — but that's a different question than the one in this paper.

### What to measure (specific metrics)

**Emotional intelligence:** Use a validated self-report scale. For adults, the Trait Emotional Intelligence Questionnaire (TEIQue) is well-validated. For children, the Bar-On EQ-i:YV. Measure before starting, after 7 weeks, and after 12 weeks.

**Mood state:** The Profile of Mood States (POMS) or the Positive and Negative Affect Schedule (PANAS) are more sensitive to short-term changes than trait emotional intelligence. Measure before and after each session to see immediate effects.

**Stress:** Salivary cortisol (collected via swab at home) before and after sessions, or daily. This gives an objective physiological measure.

**Resilience:** The Connor-Davidson Resilience Scale (CD-RISC) for adults. For children, the Child and Youth Resilience Measure (CYRM).

**Self-efficacy:** The General Self-Efficacy Scale (GSE) for adults. For children, the Self-Efficacy Questionnaire for Children (SEQ-C).

**Behavioral log:** Keep a daily journal of mood, energy, stress level (1–10 scale), and any notable events. This helps control for confounds.

### Key confounds to control for

**Season and weather:** Gardening in spring vs. winter, sunny vs. rainy days will affect experience. Run your experiment in a consistent season.

**Time of day:** Morning vs. afternoon gardening may have different effects due to circadian rhythms. Keep sessions at the same time.

**Physical activity level:** Gardening involves light-to-moderate physical activity. If you're comparing gardening to a sedentary activity, the exercise component is a confound. Control by comparing gardening to another light physical activity (e.g., walking).

**Social interaction:** Group gardening adds a social component. If you want to isolate the effect of plants, garden alone or compare solo gardening to solo reading.

**Expectation effects:** If you expect gardening to improve your mood, it probably will (placebo effect). Blind yourself by not checking your mood scores until after the experiment ends, or use an objective measure like cortisol.

**Other life events:** Stress from work, relationships, or health will confound results. Keep a log of major events and note them in your analysis.

**Baseline gardening experience:** If you already garden regularly, the intervention may have little effect. If you're a novice, the novelty might inflate results.

**Gender:** This study found gender differences. If you're testing on yourself, note your gender. If testing a group, analyze males and females separately.

### What a positive result would look like

**For emotional intelligence:** A pre-to-post increase of at least 0.2 standard deviations (roughly 5–10% improvement on the scale). For an individual, this might mean moving from "sometimes" to "often" on items like "I can tell when someone is upset" or "I know how to calm myself down when I'm angry."

**For mood (immediate):** A drop of 2–3 points on a 10-point stress scale immediately after a gardening session, or a 10–20% reduction in negative mood on the POMS.

**For cortisol:** A measurable drop in salivary cortisol (e.g., from 0.3 µg/dL to 0.2 µg/dL) within 30–60 minutes after gardening, compared to a control activity.

**For resilience/self-efficacy:** A 5–10% increase on validated scales after 8–12 weeks.

**Subjective:** You notice you're less reactive to daily stressors, recover faster from upsets, or feel more confident handling problems. Keep a journal and look for patterns.

### Bottom line for your n=1 experiment

This study provides weak evidence that gardening might help emotional well-being, especially for boys. For a self-experiment, the most rigorous approach would be:

1. **Baseline phase (2 weeks):** Measure your emotional intelligence, mood, stress, and resilience daily without any gardening.

2. **Intervention phase (8–12 weeks):** Garden for 60 minutes, 3 times per week. Continue daily measurements.

3. **Washout/control phase (2–4 weeks):** Stop gardening but continue measurements. Or better: do a crossover where you compare 8 weeks of gardening to 8 weeks of a different activity (e.g., walking, reading).

4. **Analyze:** Look at trends in your daily mood/stress scores. A positive result would be a clear downward trend in stress during the gardening phase that reverses during washout.

**Remember:** This study's biggest weakness was no control group. Your n=1 experiment will be far more informative if you include a control condition (e.g., alternate weeks of gardening vs. no gardening, or gardening vs. a different hobby). Even a simple A-B-A design (baseline → gardening → baseline) is better than a single pre-post test.