A shade net is rated by the share of sunlight it blocks, so a net sold as 50 percent shade lets roughly half the light reach the crop below it. Growers buying shade nets in agriculture in Uganda use them mostly over seedling nurseries, over cuttings being rooted, and over leafy vegetables in the hot months. The material is a knitted or woven plastic mesh, and it is a different product from insect netting.
The most common buying mistake is picking netting by colour or by price without knowing its shade rating. The second is assuming that because a net blocks light, it must also block insects. Neither holds, and both cost money.
What Shade Percentage Means When You Buy Netting for a Farm
Shade percentage is the proportion of sunlight the netting stops, not the proportion it passes. Uganda's clonal Robusta coffee nursery manual, published by the Uganda Coffee Development Authority with the Ministry of Agriculture, Animal Industry and Fisheries, spells it out in the plainest possible terms: a net of 70 to 80 percent shade means one "only allowing in 20 to 30 percent sunlight", and a net of 40 to 50 percent shade means one that "allows in 50 to 60 percent sunlight". That is the number a nursery operator asks for at a counter, and it is worth saying out loud, because half of the confusion in this market comes from people who think a 70 percent net gives them 70 percent of full sun.
Two nets carrying the same rating are not the same net. A study of three coloured nets, all rated at 50 percent shade, measured how much light each one actually passed and found transmittance to photosynthetically active radiation ranging from 22 percent under a black net to 34 percent under a green net, with a beige net in between and the ranking changing between winter and spring. The rating on the label describes how much light is stopped in total. It says nothing about which wavelengths get through, and as the section on colour below shows, that second question is the one that changes how a crop grows.
Shade Percentage by Crop Stage: Seedlings, Hardening Off and Field Crops
The clearest Ugandan guidance on shade levels comes from coffee propagation, and it generalises well because it is built around plant stage rather than around a crop. The rooting shed, where fresh nodal cuttings sit in polypots with no root system to draw water, carries a top net of 70 to 80 percent shade. In extreme hot and dry weather the manual says shade may have to go up to 90 percent, and in normal wet weather 70 percent is enough. Sides are treated separately: light entry of 50 to 60 percent at the sides is preferred, achieved with bamboo, reeds, small woven eucalyptus, or netting rated at 50 to 60 percent shade.
The hardening shed is a different structure with a different number. Plantlets there have roots and are weeks away from going to the field, so the top net drops to 40 to 50 percent shade while the sides still admit at least 50 to 60 percent light. The whole point of that shed is to walk the plant down towards full sun in a controlled way, and the netting is the instrument that does it.
That ladder is the transferable idea. Deep shade for tissue with no roots, moderate shade for a rooted plant being prepared for the field, and progressively less shade as transplanting approaches. Vegetable nurseries raising tomato, cabbage, onion or pepper seedlings are running the same physiological problem on a shorter timetable, and the same direction of travel applies. The detail of how a vegetable nursery is managed day to day sits in tomato nursery management, which covers watering, pricking out and seedling age at transplanting.
Net Colour and What It Does to Light Quality in a Crop
Black netting is neutral in the sense that it cuts light across the spectrum fairly evenly. Coloured netting does something different: it filters, so the light arriving at the leaf has a different mix of wavelengths from the light that hit the roof.
The three net study mentioned above measured this directly. Green netting transmitted more in the blue and green region between 400 and 570 nanometres and peaked at 480 nanometres. Beige netting raised the flux above 730 nanometres and peaked at 604 nanometres. Green netting raised the ratio of blue to red light, while both beige and green netting lowered the ratio of red to far red light. Black netting gave the highest ratio of photosynthetically active radiation to total solar radiation of the three nets, at 39 percent, against 44 percent measured inside the unshaded control.
Does that matter agronomically? Sometimes. A review of protected vegetable production reports that seedlings do better under a higher blue to red ratio and that green light benefits leafy vegetables, and that when other conditions are right, light intensity has the largest effect on nutritional quality, ahead of carbon dioxide, spectrum, temperature and humidity in that order. Read alongside the net measurements, that points towards a green net for seedlings and leafy crops. It is an inference, though, not a tested result: the spectral measurements and the seedling response come from different work, and nobody has run the comparison in a Ugandan nursery. Ugandan nursery guidance names black netting, so black is the defensible default and a coloured net is an experiment you run on part of a bench rather than the whole nursery.
One yield result from that same study is worth holding onto. Strawberry yields were highest under the beige net and under the unshaded control. Shading did not beat full sun. It changed the spectrum, it changed the microclimate, and the best net merely matched no net at all.
Shade Netting Against Insect Netting: Two Products Growers Confuse
These are sold side by side, they look similar on a roll, and they are specified in completely different units. Shade netting is specified by the percentage of light it blocks. Insect netting is specified by mesh count or by hole size, because what it has to do is physically stop an insect of a known body width from passing.
The gap between them is large. Excluding thrips needs a hole around 0.15 mm, whitefly and aphids around 0.35 mm, and leafminers around 0.8 mm. No shade rating tells you any of that. A 50 percent shade net has holes far wider than a whitefly, so it will shade a nursery beautifully and let the whitefly walk in. Equally, a fine insect net does cast some shade, but the shade is a side effect of the mesh rather than a specification you can order to.
The two also behave differently on airflow, and this is where a lot of Ugandan structures come unstuck. Fine insect netting chokes ventilation badly: an anti thrips screen can cut ventilation by roughly 60 to 70 percent and an anti aphid screen by about 40 percent, which raises internal temperature and humidity and can raise disease incidence rather than lowering it. The full treatment of that trade, including how vent area has to be sized around it, belongs to greenhouse ventilation. The point for a netting buyer is narrower: you cannot substitute one product for the other, and specifying a finer mesh than your pest problem requires is a cost you pay twice, once at purchase and again in lost airflow.
Research and commercial practice treat a shade net house and an insect proof net house as separate structures for exactly this reason. Where a grower needs both functions, the usual answer is insect netting on the walls sized to the target pest, with shade material over the roof, rather than one net asked to do both jobs.
How Shade Changes Plant Growth, Water Use and Disease Pressure
Shade does four things at once, and they do not all pull in the same direction.
It lowers the radiation load, which lowers leaf temperature. Work on young avocado trees under netting in a hot Mediterranean summer found that shaded trees kept their stomata more open after midday, transpired more, and ran cooler leaves than trees in the open. Their photosystem II quantum yield and electron transport rate also stayed higher after midday, which means less photoinhibition. In plain terms, an unshaded plant in fierce midday sun shuts down to protect itself and stops working for several hours; a shaded one keeps going. For a seedling with a small root system in a polypot, that difference is the difference between a saleable plant and a checked one.
It reduces water demand, because a cooler leaf transpiring under lower radiation loses less water overall even when its stomata are more open. That matters in the dry months and it is one of the reasons nursery beds under netting need watering less often than beds in the open, though they still need watering to a schedule rather than by guesswork.
It changes produce quality, in both directions. Pistachio grown under shade netting held greener kernels, retained more antioxidant capacity in storage and carried less carbohydrate, with no measurable protein difference, and yet a taste panel preferred the sun grown nuts. Shade is a quality tool, not a quality guarantee, and which way it goes depends on the crop and on what the buyer is paying for.
It raises humidity and cuts air movement, which is where shade turns against you. The Ugandan coffee nursery manual is blunt about this. Brown eyespot, which it calls the most common nursery disease, "occurs when the soil is too wet and/or there is too much shade", with lack of air movement and lack of nitrogen and potassium listed as aggravating factors. The cultural controls it gives are avoiding overwatering, maintaining 50 percent shade cover, proper fertilizer use, and opening the propagation cages for at least two hours early in the morning between six and eight. A nursery that adds shade to fix a scorching problem and does nothing about airflow has traded sunburn for leaf spot.
Where Shade Costs Yield: Full Sun Crops Under Netting
Shade netting is not a general improvement. For a crop that wants full sun and is grown for fruit, light is the raw material of yield, and taking a third of it away takes yield with it.
A trial in a hot arid region compared tomato in three low technology protected structures: a naturally ventilated polyhouse, an insect proof net house, and a shade net house. The polyhouse beat both net houses on leaf and stem dry mass, on fruit size, fruit weight and yield, and on quality measures including total soluble solids, fruit dry matter and lycopene, regardless of the irrigation level applied. Microclimate was most favourable in the polyhouse, then the insect net house, and least favourable in the shade net house. The same trial found that cutting irrigation below full crop water requirement depressed growth and yield in all three structures, so deficit irrigation under these low cost structures was not workable.
That is one trial in one climate, and a Ugandan site is wetter and less extreme. The direction is still the honest one to report: a shade net house is the weakest of the three structures for a fruiting crop like tomato, and the reason growers in the region build polythene houses for tomato rather than net houses is not fashion. If rain exclusion in the wet season is the problem you are solving, netting does not solve it, and greenhouse farming in Uganda explains why a covered house is the tool for that job.
Shade earns its place where the plant is small, rootless, or grown for leaf rather than fruit. Seedlings and cuttings above all. Hardening off. Leafy vegetables in the hottest months, where a cooler bed and a slower bolting rate are worth more than maximum radiation. Nursery stock of tree crops and coffee. Outside that, treat every percentage point of shade as yield you are choosing to spend.
UV Stabilisation and How Long Shade Netting Lasts on a Ugandan Farm
Netting fails by ultraviolet degradation. Sunlight breaks down the plastic filament, the mesh loses tensile strength, and eventually it tears at the points where it is under tension or rubbing against a support. Uganda sits on the equator at altitude, which means high annual ultraviolet exposure, so a net here is working harder than the same net in a temperate country.
Stabilised netting has additives blended into the plastic to slow that breakdown, and the amount of stabiliser is what separates a net that lasts from one that shreds in a season. What follows is the part suppliers do not like: the service life figures quoted for agricultural netting are supplier warranty claims, not independently measured lifespans. No published measurement of shade net service life under Ugandan conditions could be found for this article, so no number is given here. Ask for the warranty period in writing, ask what voids it, and treat the answer as a commercial promise rather than a technical specification. The separate question of how long greenhouse polythene film lasts, which is better documented, sits in the greenhouse construction guide.
What you can control is the mechanical side, and it is usually what kills netting first in practice. Abrasion at every point where the net crosses a support multiplies the effect of ultraviolet damage, so a net stretched over rough sawn timber or an unpadded pole end wears through at those lines while the rest of the sheet is still sound. Sagging netting flaps in wind and works itself apart at the fixings. Netting left slack over a bed collects debris and water, then loads and tears in the first heavy storm. Tension it properly, pad or round off anything it bears on, and inspect the fixing lines rather than the middle of the sheet.
Specifying and Fitting Shade Netting Over a Nursery or Crop Bed
Fitting is where the specification either works or is wasted. Netting wants to be taut, supported often enough that it does not pond, and fixed in a way that spreads load along an edge rather than concentrating it at a few points.
Run the netting so it can be removed. This is not obvious and it matters more than most build details, because shade is a variable you should be changing: a hardening batch needs less shade than a rooting batch, the dry season needs more than the wet season, and the coffee nursery manual explicitly moves between 70 and 90 percent depending on weather. A net permanently nailed to a frame means you get one shade level for the life of the structure, and the one you happen to have bought.
Keep the roof net and the wall material as separate decisions with separate ratings, exactly as the Ugandan nursery guidance does. The roof sets the light level over the crop. The walls set side light and air movement, and that is where woven eucalyptus, reeds or bamboo do a job that netting does not necessarily do better or cheaper.
Leave a way in that does not involve lifting the net. Every time someone drags netting aside to reach a bed, the same fixing takes the strain, and that is the fixing that fails. The structural side of all this, including frame material, pole height, bed layout and door design, is the subject of nursery shade house construction, which treats the netting as one component of a building rather than as a product on a shelf.
Shade Netting Mistakes That Cost a Seedling Crop
The expensive errors repeat, and none of them are exotic.
One more that is harder to see: watering a shaded bed on the same schedule as an unshaded one. A bed under 70 percent shade dries far more slowly, and overwatering a shaded nursery bed is a disease invitation rather than a kindness. The soil surface, not the calendar, decides.
Shade Nets in Agriculture: Questions Growers Ask
What does shade netting cost in Uganda? Netting is sold by the roll or by the square metre, and the price moves with roll width, shade percentage, whether the edges are reinforced, and the exchange rate, since the material is imported. Expect a fine, heavily stabilised net to cost several times a light one of the same area, and expect prices quoted to a nursery buying a full roll to differ from prices quoted for a few metres. Rather than chase a spot figure that will be stale by the time you shop, price the same specification at three suppliers on the same day and compare cost per square metre at the same shade rating. Where netting is one line in a whole structure budget, greenhouse cost in Uganda sets out how the other components stack up, and where to buy greenhouses covers the supplier side.
Is a 50 percent net right for a vegetable seedling nursery? It is a reasonable starting point for seedlings in trays and a common default, and it is the level Ugandan nursery guidance names as a cultural control ceiling for nursery leaf disease. Cuttings with no roots want considerably more shade than that. Plants within a fortnight of transplanting want less.
Can I use old mosquito netting or sacking instead? As a stopgap over a small bed, growers do, and it casts shade. What you lose is a known shade percentage, ultraviolet stabilisation and any edge strength, so the shade level is a guess and the material fails without warning. For a nursery you are selling from, that guesswork is the wrong economy.
Does black netting get hotter than coloured netting? Black netting absorbs more and passed the least photosynthetically active radiation of the three colours measured in the study cited above, so less light reaches the crop for the same nominal rating. Whether the air under it is hotter depends far more on how freely air moves through and out of the structure than on the colour of the mesh.
Will shade netting stop hail or heavy rain damaging seedlings? It breaks the force of falling water and reduces the battering a tray of seedlings takes, which is a real benefit in a Ugandan storm. It does not exclude rain, so it does not stop a wet medium, and it does not give you the disease control that rain exclusion under a covered house does.
How do I know the net I was sold is the rating on the label? Honestly, on a farm you mostly cannot measure it. What you can do is compare the roll against a net of known rating side by side in the same light, buy the same specification from the same supplier once it works, and keep a note of the roll details so a replacement matches. Growers who skip that step end up with three shade levels in one nursery and no idea which bench is which.
Should the sides of a shade structure be netted too? Ugandan nursery guidance treats sides separately and asks for 50 to 60 percent light entry at the sides, from netting or from woven eucalyptus, reeds or bamboo. Fully enclosing the sides with the same heavy net as the roof is how nurseries end up with stagnant air and leaf disease.
Shade netting is a small purchase that decides the quality of every plant that passes under it, so it pays to specify it properly rather than buy whatever roll is on the shelf. Ask suppliers for the shade percentage, the roll width and the warranty in writing before you compare prices, and check current rates with more than one dealer, since imported netting moves with the exchange rate. The wider set of water and structure guides sits under irrigation, greenhouses and water, and if you are weighing up the nursery as a business rather than as a bench, starting a seedling nursery is the next thing to read.