Getting the distance right between your plants and their grow lights is one of the most important parts of indoor gardening. Too close, and leaves burn. Too far away, and plants stretch weak and leggy. This guide explains the best grow lights distances for seedlings, vegetative plants, and flowering crops, plus a handy grow lights distance chart for UK growers.
Not quite what you’re looking for? Take a look at our Grow Lights UK – Complete Resource Hub for a full overview of light types, setup tips, and running costs.
Why Grow Lights Distance Matters
Grow lights provide the intensity and spectrum that plants can’t always get from natural UK daylight — especially in winter. But if grow lights are set at the wrong height:
- Too close: leaves bleach, curl or scorch from heat.
- Too far: seedlings grow thin and spindly, fruiting plants may never ripen.
Correct spacing of grow lights gives:
- Strong seedlings
- Compact leafy growth
- Reliable flowering and fruiting
Grow lights are especially useful for:
- Fresh winter salads grown indoors
- Getting a head start on tomatoes
- Growing herbs and vegetables in low-light kitchens or lofts
General Grow Lights Distance Guidelines
- LED grow lights: 12–24 inches (30–60 cm), depending on power.
- Fluorescent grow lights (T5/CFL): 2–6 inches (5–15 cm) — cooler so they can sit close.
- HPS grow lights: 24–36 inches (60–90 cm) — very hot, so more clearance needed.
⚠️ Household bulbs are not suitable — they don’t produce the right spectrum or strength for plant growth.
Grow Lights Distance by Plant Stage
Seedlings
- LED grow lights: 24–30 in (60–75 cm)
- Fluorescent grow lights: 2–4 in (5–10 cm)
- HPS grow lights: not ideal
Vegetative Growth
- LED grow lights: 18–24 in (45–60 cm)
- Fluorescent grow lights: 4–6 in (10–15 cm)
- HPS grow lights: 24–36 in (60–90 cm)
Flowering & Fruiting
- LED grow lights: 12–18 in (30–45 cm)
- Fluorescent grow lights: ~6 in (15 cm)
- HPS grow lights: 18–24 in (45–60 cm)
LED Grow Lights Distance by Wattage
Not all LED grow lights are equal — distance depends on wattage and power output.
- 100–150W LED grow lights (herbs, seedlings, salad greens)
- Seedlings: 24–30 in (60–75 cm)
- Vegetative: 18–24 in (45–60 cm)
- Flowering: 12–18 in (30–45 cm)
- 300–450W LED grow lights (medium setups)
- Seedlings: 30 in (75 cm)
- Vegetative: 20–24 in (50–60 cm)
- Flowering: 14–18 in (35–45 cm)
- 600–1000W LED grow lights (large/high-output panels)
- Seedlings: 36 in (90 cm)
- Vegetative: 24 in (60 cm)
- Flowering: 18–20 in (45–50 cm)
⚠️ Always check the manufacturer’s leaflet and watch for plant stress, as spectrum, lens angle and heat vary.
Grow Lights Distance Chart
| Plant Stage | LED Grow Lights | Fluorescent Grow Lights | HPS Grow Lights |
|---|---|---|---|
| Seedlings | 24–30 in (60–75 cm) | 2–4 in (5–10 cm) | Not recommended |
| Vegetative | 18–24 in (45–60 cm) | 4–6 in (10–15 cm) | 24–36 in (60–90 cm) |
| Flowering | 12–18 in (30–45 cm) | ~6 in (15 cm) | 18–24 in (45–60 cm) |
Light Spectrum and Grow Lights
Distance is only part of the picture. Plants respond to different wavelengths of light:
- Blue light (400–500 nm): Encourages compact leafy growth in vegetative stage.
- Red light (600–700 nm): Triggers flowering and fruiting.
- Full-spectrum grow lights: Combine both for a balance that mimics sunlight.
This is why modern LED grow lights often blend blue, red, and white diodes in a single fixture.
Troubleshooting Grow Lights Placement
Too close to plants
- Pale, bleached leaves
- Curled or crispy edges
Too far from plants
- Dark-green but weak foliage
- Long, stretched stems
Heat stress
- Leaves curl upward or dry at the tips
Solution: raise or lower your grow lights gradually and keep observing plant response.
Tips for Adjusting Grow Lights Height
- Start higher, lower slowly to avoid burning.
- Raise grow lights as plants grow taller (every 1–2 weeks).
- Rotate pots weekly for even coverage.
- Use a PAR/lux meter or phone app for accuracy.
Conclusion
The correct grow lights distance depends on both plant stage and lamp strength. Use the chart and wattage ranges as a starting point, but always check your manufacturer’s guidance and observe your plants.
For more practical advice, you may also like:
- 🌱 Best Indoor Grow Lights UK Beginners Guide (2025)
- 💡 How to Set Up Grow Lights Indoors
- 🔧 Top 10 Grow Light Stand Systems (2025)
Looking for more self-sufficiency and gardening guides? Visit HomeGrower to explore all our latest indoor and outdoor growing tips.
And for background on grow lights generally, see the Royal Horticultural Society’s website.
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How far should grow lights be from seedlings?
Seedlings are sensitive to too much light. LED grow lights should be 24–30 inches (60–75 cm) above seedlings, while fluorescent grow lights can sit much closer at 2–4 inches (5–10 cm).
Do stronger LED grow lights need to be hung higher?
Yes. High-wattage LED grow lights (600W+) produce more intensity and should be placed further away than smaller 100–150W panels. Always check your manufacturer’s guide.
What happens if grow lights are too close to plants?
Leaves may bleach, curl, or burn, and growth can stall. If plants show stress, raise the lights gradually.
Can I use normal household bulbs as grow lights?
No. Regular bulbs don’t provide enough intensity or the right light spectrum. Use LED, fluorescent, or HPS grow lights designed for plants.
How do I know if my plants are getting the right amount of light?
Healthy plants stay compact with strong stems and vibrant leaves. If they stretch and lean, lights are too far. If leaves scorch or curl, lights are too close.