Shade cloth is a woven fabric stretched over plants to reduce the amount of direct sun and heat they receive. It is the opposite of a cloche or a cold frame: instead of trapping warmth, it keeps a plant cooler, and it is used when the sun is too strong, the heat is too high, or a plant needs protection from scorching. Lettuce that bolts in summer heat, seedlings that wilt by midday, and shade-loving plants in a sunny garden all benefit from shade cloth. This guide covers how shade cloth works, how to choose the right level of shade, and how to fit and use it.
Shade cloth works by blocking a proportion of the sunlight that reaches the plant, which lowers the temperature of the leaves and the soil, reduces water loss, and prevents sun scorch. It is sold by shade percentage — the proportion of light it blocks — and the right percentage depends on the plant and the climate. A light shade cloth that blocks roughly a third of the light suits most vegetables in a hot summer, because it cools them without starving them of light. A heavier cloth that blocks half or more of the light suits shade-loving plants, seedlings, and plants in very hot, sunny climates. Do not use a heavy shade cloth over sun-loving crops such as tomatoes and peppers, because they need full sun to fruit well, and heavy shade will cut their yield. If you are unsure what your plants need, check your local extension service for advice suited to your area and climate.
When to use shade cloth
The main use is in summer, when strong sun and heat stress plants. Lettuce, spinach, chard and other leafy greens bolt — run to seed and turn bitter — in hot sun, and shade cloth can keep them productive for weeks longer. Young seedlings and transplants, which have small root systems and cannot replace water fast, wilt quickly in strong sun, and shade cloth helps them establish. Newly planted trees, shrubs and perennials also benefit from shade for their first summer. Shade-loving plants such as ferns, hostas and many houseplants moved outside for summer need shade cloth if they are in a sunny spot. Shade cloth is also useful over a greenhouse in summer, where it stops the inside overheating, and over a cold frame that would otherwise cook the plants inside it. Our cold frames guide covers cold frame ventilation, and greenhouse heating covers the winter side of greenhouse care.
Fitting shade cloth
Shade cloth needs to be held above the plants, not laid directly on them, because fabric lying on leaves can scorch them and trap heat. The usual method is to fix it to a frame, a pergola, a fence, or posts with wire or rope, leaving a gap of air between the cloth and the plants so air can circulate underneath. A simple frame of four posts with the cloth stretched over the top works well over a vegetable bed, and a hoop structure covered with shade cloth works over a row. Fix the cloth firmly at the corners and edges, because it catches the wind like a sail, and a loose cloth flaps, damages plants, and can tear or blow away. Leave the sides open where you can, so air flows through and the temperature under the cloth does not build up. For a greenhouse, shade cloth is usually fitted outside the glass, where it stops the sun heating the glass, or inside as a blind — outside is more effective, because it blocks the heat before it enters.
Take shade cloth down when the hot weather passes. Plants that are shaded all season will grow weak and pale, and sun-loving crops need full sun to fruit. In most gardens, shade cloth is a summer tool: put it up when the heat arrives, and take it down in autumn so plants get the full light of the cooler months. Clean it before storing it, let it dry fully, and store it dry and out of direct sun so it lasts longer.
Choosing the right shade level
The right shade level is a balance: too little shade and the plants still scorch; too much and they grow weak and yield poorly. For most vegetables in a hot summer, a light to medium cloth is the right choice. For seedlings, cuttings and shade-loving plants, a medium to heavy cloth suits them better. For a greenhouse in summer, a medium cloth over the roof stops the worst of the heat while still letting in enough light for plants to grow. Colour matters too: black shade cloth absorbs heat and can make the area underneath warmer if there is no air gap, while white or light-coloured cloth reflects more heat and keeps the area cooler. In a hot climate, a light-coloured cloth is usually the better choice for vegetables. Check the product description for the shade percentage and the recommended use before you buy, and start with a lighter cloth — you can always add a second layer if the plants still scorch.
Watering and care under shade cloth
Plants under shade cloth lose less water than plants in full sun, so they need watering less often — but they still need water. Check the soil with a finger before watering, and water at the base of the plants in the morning so the leaves dry out during the day. Do not assume shaded plants never need water: the soil under a cloth can still dry out in a hot, windy spell. Keep the area under the cloth clean and well ventilated, because a still, damp, shaded area can encourage slugs and mould. Our slug control guide covers organic-first methods if slugs become a problem. If you are growing lettuce, spinach or herbs under shade cloth, our guides for growing lettuce, growing spinach and growing basil give crop-by-crop detail.
Common mistakes
The most common shade cloth mistakes are using too heavy a cloth so plants grow weak and yield poorly, laying the cloth directly on the plants so it scorches them, fixing it with no air gap so heat builds up underneath, leaving it up all year so plants never get full sun, and fixing it loosely so it flaps and blows away. Another is using shade cloth as a fix for a plant in the wrong place: a sun-loving plant in shade will not thrive under a cloth, and a shade-loving plant in full sun is better moved to a shady spot than covered. The fixes are simple: choose a light to medium cloth for vegetables, hold it above the plants with an air gap, fix it firmly, take it down when the heat passes, and put the right plant in the right place in the first place.
Frequently asked questions
What shade cloth percentage should I use for vegetables?
For most vegetables in a hot summer, a light to medium cloth is the right choice — enough to cool the plants and stop scorching, but not so heavy that it starves them of light. Seedlings, cuttings and shade-loving plants suit a heavier cloth. Start with a lighter cloth and add a second layer only if the plants still scorch.
Can shade cloth stop lettuce bolting?
It helps. Lettuce bolts in hot sun, and shade cloth keeps the leaves and soil cooler, which delays bolting and keeps the leaves sweet for longer. It will not stop bolting entirely in a long hot spell, but it can extend the harvest by weeks. Sow a little and often as well, so you always have young plants coming on.
Should shade cloth touch the plants?
No. Shade cloth should be held above the plants on a frame, posts or hoops, with a gap of air between the cloth and the leaves. Fabric lying on leaves can scorch them, trap heat, and damage the plant. Leave the sides open where you can so air can flow underneath.
Can I use shade cloth on a greenhouse?
Yes, and it is one of the best ways to stop a greenhouse overheating in summer. Fit it outside the glass where possible, because it blocks the heat before it enters, and take it down in autumn so plants get the full light of the cooler months. A medium cloth over the roof is usually enough.
Is white or black shade cloth better?
For vegetables in a hot climate, a white or light-coloured cloth is usually better, because it reflects more heat and keeps the area underneath cooler. Black cloth absorbs heat, which can make the area underneath warmer if there is no air gap. The shade percentage matters more than the colour, so choose the right percentage first and the colour second.