Courgettes Garden Myths: What Holds Up

“A scatter of Epsom salts will green plants up and stop blossom end rot”

Epsom salts are magnesium sulfate, and they contain no calcium whatsoever, so they cannot address a calcium problem. Worse, magnesium and calcium compete for uptake, so adding magnesium can make blossom end rot more likely rather than less. Most garden soils hold plenty of magnesium already, and adding more unbalances what is there.

Our read Blossom end rot is not a soil shortage in the first place. It is about calcium reaching the fruit, which is governed by steady watering, so the fix is a watering can and a mulch rather than anything you buy.

What to do: Water consistently and mulch to hold that moisture steady. Use Epsom salts only if a soil test has actually shown a magnesium deficiency, which is uncommon.

“One courgette plant is plenty — they feed a family on their own”

A single courgette plant produces steadily rather than overwhelmingly. It gives one or two fruits at a time across the season, which is a contribution to a household rather than a glut. The reputation comes from people who planted four and blamed the fourth when they could not keep up.

Our read Two plants is the practical minimum for a family that actually eats courgettes regularly. One plant means a fruit every few days, which is a side dish rather than a supply.

What to do: Plant at least two, spaced about a metre apart. Three gives you enough to give away. One leaves you buying courgettes in August while staring at a single fruit on the plant.

“If your courgette only makes male flowers you won't get any fruit”

Courgettes always produce male flowers first, sometimes for a week or two before the first female appears. This is normal plant behaviour rather than a problem. Dry soil at the roots delays female flower production, so the fix is watering, not panicking.

What to do: Wait. Male flowers appearing first is the normal sequence. Water consistently and the females will follow. If the plant is producing only male flowers well into the season, dryness is the usual cause.

In Scotland: In a cool, wet Scottish summer the opposite can happen: female flowers appear but are not pollinated because insect activity is low. Hand-pollinate with a small brush if you see fruit forming then rotting at the tip.

“Courgettes need full sun or they won't produce anything”

Full sun produces the heaviest crop, but courgettes are more tolerant of partial shade than their reputation suggests. A sheltered position in full sun is advised, though the plants are productive under a wide range of conditions. Light shade reduces the crop rather than eliminating it.

What to do: Give them the sunniest spot you have, but do not skip growing courgettes because the only available bed gets shade in the afternoon. A plant in partial shade will still crop, just more slowly.

In Scotland: A Scottish 'full sun' position is already lower in total light than the south of England, so give them the best light you have. The gap between full sun and partial shade is narrower here.

“A courgette is a courgette — one variety is as good as another”

Varieties differ in habit, disease resistance, and productivity. Bush and trailing types, green and yellow varieties all differ, and some have better powdery mildew resistance than others. Picking the right one for your space and climate makes a real difference.

What to do: Choose a bush variety for containers or small plots, and a variety with good powdery mildew resistance for a Scottish summer where humidity drives fungal disease.

In Scotland: Mildew resistance matters more here than in drier parts of Britain. A variety like 'Defender' bred for resistance will crop weeks longer than a susceptible variety in a wet Scottish August.

“Getting water on courgette leaves when you water gives them powdery mildew”

RHS advice runs counter to the common rule of thumb. Drought-stressed plants are more susceptible to powdery mildew, not well-watered ones, and direct water contact on leaves can actually reduce the disease because the fungus doesn't like it — done in mid-morning during dry weather. The real risk is leaves staying wet for long stretches, which favours other diseases, which is why evening overhead watering is discouraged.

What to do: Keep courgettes consistently watered rather than letting them dry out. If watering overhead, do it in mid-morning so foliage dries by evening; avoid watering late in the day.

In Scotland: Scotland's cooler, often already-humid growing conditions mean drought stress is less often the trigger here than it is further south — good airflow between plants matters more locally than worrying about the hose touching leaves.

“Dig sand or grit into heavy clay to break it up”

The quantities involved make this hopeless at garden scale. Meaningfully diluting a soil that is 40 per cent clay takes around 250kg of grit or gravel per square metre. A barrowload does nothing, and adding modest amounts can destabilise the structure and leave the ground harder to work than before you started.

What to do: Add bulky organic matter instead: manure or composted bark, dug in generously. Raise beds to lift roots above the wet, and consider not digging at all. Those three do what the sand was supposed to do, and they compound each year rather than needing repeating.

In Scotland: Heavy clay runs right through the Central Belt, so this is one of the most expensive mistakes a Scottish grower can make. Two tonnes of grit for a small bed is not a purchase anyone makes twice.

“You have to dig the ground over each year to keep the soil fertile”

Digging works against fertility rather than for it. Turning the ground releases soil nitrogen and damages the soil's biology. The structure that fungi, worms and roots build up over a season is undone every time the spade goes through it.

What to do: Leave the ground alone and feed it from the top. Spread compost or well-rotted manure on the surface and let the soil life pull it down. Dig only where you actually need to, such as lifting root crops or clearing perennial weeds.

In Scotland: There is a practical bonus here: undug ground carries weight better and warms marginally earlier in spring than freshly turned wet soil, which matters when the season is already short.

“Peat-free compost doesn't grow plants as well as the peat stuff”

This was a fair complaint a decade ago and it has not aged well. Peat-free quality has greatly improved in recent years, and dedicated research has found some carnivorous plants grow better in peat-free mixes than in peat. What is true is that peat-free behaves differently: the watering and feeding requirements are not the same, because the ingredients have different physical and chemical properties from peat.

Our read Most bad experiences with peat-free are a watering problem rather than a compost problem. It dries differently, so the habits you built on peat will let you down for a season until you adjust.

What to do: Read the bag rather than assuming, since feeding and watering advice genuinely varies between mixes. Buy fresh: old stock breaks down and performs worse regardless of what it is made of. If one brand disappoints, try another rather than writing off the category.

In Scotland: This matters more here than almost anywhere in Britain. Scotland holds a great deal of the UK's peat, those peatlands are major carbon stores, and peat-based compost comes out of them. The performance excuse for buying peat no longer holds up.

“Plants do better in pots than in the ground”

A container limits how far roots can spread and cuts the plant off from the reservoir of moisture and nutrients that open ground provides, increasing the need for both watering and feeding. You are taking on work the soil would have done for free.

Our read Pots are a solution to a problem, not an upgrade: no ground, bad drainage, a crop that needs containing, or somewhere warm against a wall. Chosen for those reasons they are excellent. Chosen by default they make the job harder.

What to do: Use the ground where you have it. Where you do use pots, go bigger than feels necessary, expect to water far more often, and feed through the season because there is no soil reserve to draw on.

“Strong-smelling plants confuse pests and hide your crop”

This is the theory underneath half of every companion planting chart, and it is the wrong mechanism. Research at Wellesbourne, Britain's long-standing centre for brassica and carrot pest work, found that insects hunting a host land on green and avoid bare brown soil. Colour, size and shape decide where they settle. Artificial green plants, and even green paper releasing nothing at all, disrupt them as well as living companions do, and aromatic plants perform no better than bland ones.

What to do: Stop choosing companions by scent. If ground cover is what disrupts the pest, the useful question is whether something low and green grows between your rows, not whether it smells of anything.

“Crushed eggshells, bark mulch or wool pellets stop slugs”

Testing the most popular home slug barriers found no reduction in damage from crushed eggshells, bark mulch or wool pellets. This is Britain's most repeated slug advice and it does not work.

What to do: Skip the barrier. Nematodes, evening hand-collection, and raising plants to a decent size in modules before planting out all do more.

In Scotland: This one costs us more than most. A wet, mild climate is close to ideal for slugs, so a barrier that does nothing is a bigger loss here than in a dry southern garden where the pressure is lighter anyway.

“Watering in sunshine scorches the leaves”

Water droplets do not focus sunlight enough to burn foliage. Scorch on new plants comes from insufficient hardening off far more often.

What to do: Water whenever the plant needs it. Watering at ground level rather than over the leaves is still worth doing, but for disease and evaporation reasons, not for scorch.

In Scotland: Rarely the limiting factor here anyway, though it matters under cover, where watering habits drive humidity and therefore disease.

“Coffee grounds acidify your soil and feed your plants”

Grounds do contain nitrogen, phosphorus, potassium and magnesium, so the feeding half is not baseless. The acidifying half is not: their effect on pH is very minor and temporary. Spread thick they cap the soil and block water and air, and residual caffeine can suppress root and shoot growth.

What to do: Put them in the compost bin rather than straight on the bed. If you actually need to change pH, that is a job for lime or sulphur guided by a soil test, not for coffee.

In Scotland: Most Scottish soils are naturally acidic already, so the acidifying claim solves a problem you probably do not have and may worsen one you do.