Greenhouse Shading Guide: When, Why and Which Method to Use
Greenhouse shading helps protect plants from strong sun, but it works alongside ventilation rather than replacing it. Paint provides broad seasonal coverage, while netting and curtains are easier to adjust as the weather changes. Start by checking your vents, then choose shading that fits your greenhouse and the plants inside. The aim is enough protection from heat without making the growing space unnecessarily dark.
Key takeaways
- Ventilate first. Shade cannot release hot air trapped inside a closed greenhouse.
- Use your thermometer and plant condition, not a fixed calendar date.
- Choose adjustable shading if you want to uncover plants on dull days.
- Check fabric dimensions and fixings before buying. A floor size is not a roof measurement.
- Keep shading clear of vent arms, sliding doors and hot appliances.
Expert tip
Before adding another layer of shade, check the compost. A plant with dry roots struggles in strong sunshine. Equally, wilting does not always mean it needs more water. If the compost is already wet, improve airflow and shelter first.
Why does a greenhouse need shading?
A greenhouse can become too hot for its plants even when the garden feels pleasant. Sunlight warms the surfaces inside, and the enclosed space slows heat loss. The glass is not acting like a magnifying lens.
Scorched leaves, wilting and poor flower set can all follow excessive heat. Different plants respond differently, so there is no single temperature at which every crop suddenly fails. Check a thermometer near plant height, out of direct sun, and look at the plants themselves.
Shade reduces the incoming sunlight. Open vents let warm air escape. Watering keeps the roots supplied without leaving them waterlogged. These jobs complement each other; none makes the others unnecessary. Our greenhouse cooling guide covers the wider hot-weather routine.
When should you shade your greenhouse in the UK?
Start watching for overheating in spring and adjust protection through summer. A bright April day can cause trouble, while a cloudy June week may need little shading.
Check the greenhouse during a sunny afternoon before deciding what to cover. Notice where direct sun falls and whether your most sensitive plants are in that strip. Moving a tray of young plants into a shaded corner may be enough; mature fruiting crops still need plenty of light.
Reduce shading as autumn light fades, rather than leaving it up out of habit. Adjustable curtains make that easy. Paint takes more planning because removal depends on the product. Reduce shade when ventilation alone can manage overheating.
Which greenhouse shading method should you choose?
The useful difference is how easily you can adjust the shade. Here is a quick comparison without promised temperature reductions or assumed lifespans.
| Method | Useful when | Check first |
|---|---|---|
| Shading paint | You want broad coverage during sunny weather | Glazing compatibility, application and removal instructions |
| Internal netting | You want removable shade attached to the frame | Sheet dimensions and compatible lining clips |
| Draw-back curtains | You want to uncover plants on dull days | Space to gather the fabric and the required fittings |
| External shade cloth | You can secure it safely outside | Wind exposure and full roof-vent movement |
| Nearby planting | An existing tree or plant gives useful seasonal shade | Roots, falling debris and unwanted winter shade |
Our greenhouse shading and clips collection is the place to compare current sizes and prices. Choose for your particular frame, not just the brand name on a similar-looking greenhouse.
Shading paint: simple seasonal coverage
Purpose-made greenhouse shading paint is useful when you want to cover a large area without installing hanging fabric. It is less convenient when the weather switches between bright and overcast.
Read the label before applying it. Mixing, drying time, rain resistance and autumn removal vary between products. Do not assume a paint suitable for glass is also suitable for polycarbonate, or that a small test patch replaces the manufacturer's approval.
Apply it only where you can work safely. Never stand on greenhouse glazing or lean your weight against a pane. If a roof section cannot be reached safely, use a suitable alternative or arrange help.
Internal netting and curtain shading
Removable shading is convenient for a greenhouse that holds several different crops. You can shade a propagation area while keeping established tomatoes in stronger light.
The Elite netting kit contains a 20ft by 6ft sheet and 30 lining hooks. Elite describes it as an internal system that can be cut to size. Measure the surfaces you intend to cover before deciding how much you need. A long greenhouse may need more than one sheet.
Current price: £99. Check the product page for the available options and fitting details.
Vitavia curtain shading offers a draw-back option for changing weather. Its listed fabric size is 1830mm by 2590mm; the required screwhooks are sold separately. Check the current fitting details for your greenhouse before ordering.
Current price: £36. Check the product page for the available options and fitting details.
Neither system should hang across a vent opening or catch the moving arm of an automatic opener. After fitting, open every vent fully and walk through the greenhouse with the door moving normally. This simple check is easier before the plants grow into the fabric.
Can you shade a polycarbonate greenhouse?
Yes. Diffused light through polycarbonate does not prevent a greenhouse overheating. Removable internal cloth is often a practical option.
The Palram Canopia shade kit is a separate fitting system, not a reason to assume all greenhouse clips are interchangeable. Check the compatible greenhouse range and use the supplied instructions. Avoid drilling frame members or forcing a fixing into the wrong channel.
Current price: £55. Check the product page for the available options and fitting details.
For paint, check both the coating label and the greenhouse manufacturer's guidance. If either rules it out, use another method. There is no need to risk permanently marking the panels just to get summer shade.
Is internal or external greenhouse shading better?
External shading intercepts sunlight before it reaches the glazing. Internal shading is sheltered from the weather and is often easier to fit and adjust.
That does not translate into a guaranteed percentage advantage or temperature drop. Ventilation, wind, fabric coverage and the weather all affect the result. External cloth also needs secure, suitable fixings. A loose sheet can flap against glass, and a tightly stretched one can prevent roof vents opening.
For an ordinary hobby greenhouse, ease of safe adjustment matters. Choose external shading only if you can fit, inspect and remove it properly. Keep working space around the structure and never use roof glazing as a support.
Which greenhouse crops need the most shade?
Young plants and soft cuttings often need more protection from strong sun than established fruiting crops. Grouping them together makes targeted shading easier.
Tomatoes, peppers and aubergines need good light to crop well. Start with airflow and enough root moisture, then add shade where it is needed. Avoid turning the whole greenhouse into a dark room for one sensitive tray.
Orchids are not a single light-requirement group. Match protection to the particular orchid rather than following one percentage for every type. The same caution applies to cacti, succulents and seedlings.
If you buy shade cloth labelled with a shading percentage, treat it as a fabric specification, not a promise about air temperature. Check how your plants respond before adding another layer.
How do shading and ventilation work together?
Openings let heat escape; shading reduces the heat arriving. On hot days you usually need both.
Check that vents actually open, rather than assuming an automatic opener is working. Keep the mechanism clear and follow its adjustment instructions. Our auto-vent fitting guide explains that setup. The ventilation guide covers the choice of openings.
Damping a suitable path can raise humidity through evaporation, but it is not a substitute for watering dry compost. Avoid electrical equipment, slippery surfaces and prolonged damp around disease-prone crops. There is no reliable fixed number of degrees to promise.
Before a holiday, check the complete arrangement on a sunny day. Arrange someone to look in, even if watering and vents are automated. Our watering and irrigation guide covers those checks.
Matt's tip: make it easy to adjust
Choose a setup you can reach and change without moving half the greenhouse. If taking shade down is awkward, it is likely to stay up through dull weather. Leave a clear place to gather curtains or roll back netting.
Frequently asked questions
What is the best shading for a greenhouse?
Choose shading you can fit safely and adjust when needed. Internal netting and curtains are practical for many hobby greenhouses. Paint provides broader seasonal coverage but is less adjustable.
When should I shade my greenhouse in the UK?
Add shade when strong sun causes overheating despite good ventilation. Start monitoring in spring and reduce coverage as autumn light fades. Your crops and local conditions matter more than a fixed date.
Should I shade the inside or outside of my greenhouse?
Either can work, provided the fittings and ventilation remain suitable. External shading intercepts sunlight before the glazing, while internal shading is sheltered and usually easier to adjust.
What percentage shade cloth is best for a greenhouse?
There is no single percentage that suits every crop. Use only enough shade to protect the plants, then check light levels and growth. The fabric rating is not a promised temperature reduction.
Does greenhouse shading paint wash off in the rain?
That depends on the product. Check its label for rain resistance, drying time and removal instructions. Do not assume all greenhouse paints behave alike.
Can I shade a polycarbonate greenhouse?
Yes, using compatible cloth, fixings or an approved coating. Check the greenhouse and shading manufacturers’ instructions. Paint may leave permanent marks on unsuitable panels.
How do I stop my greenhouse overheating without shading?
Start with ventilation and checking moisture around the roots. Open suitable vents and doors, and confirm automatic openers work. In strong sunshine you may still need some shading.
