Helping your plants survive the excesses of summer heat

Fiann Ó Nualláin offers advice on how to protect your plants from heat stress and heavy rains during summer

IF you missed last week’s article on how to avoid those heat emergencies that gardeners may suffer from (prickly heat to heat stroke) — it is up online in the archives. Well worth a look.

I am not trumpeting my writing skills but instead, urging you to take your health and safety seriously. While the masses are just burning up oxygen and Snapchatting their abs, we are out there planting oxygenators and growing good food — we can’t afford to be dropping like flies. The survival of humanity requires gardeners.

Meanwhile… This week it is all about helping our plants survive the summer excesses — from drought and heat stress to torrential downpour.


If we have a water reservoir, rain barrel or other catchment device, then we can continue to water in hot weather and negate the drought occurring elsewhere. It is best to create a shading device — this can be an umbrella or a board angled to cast shade — so that we water the plant in shade and so, slow evaporation. It is best to short burst water at the roots and let it soak in (this stops run off and creates a pathway to the roots), before giving the plant a good drink.

If you haven’t a store of water —
remember that tap water-related stress (chlorosis etc), can show up faster in drought-stressed plants. Here’s how to revive a wilted plant — get it to shade if it’s in a container or get shade to it, if it’s in the ground. Dampen the root zone then water well at the roots, wait 20 minutes and water again. Misting the plant’s foliage can help the plant to start photosynthesising. Keep it in the cool shade until you see it fully perked up.

Heat stress:

In the ornamental garden and the vegetable patch heat stress manifests as wilting — all the water loss of evaporation and the lack of moisture in the soil to draw up to maintain turgor pressure in the stems, causes plants to flop. The problem with the flop is that the plant is no longer able to photosynthesis in that situation — so it’s not only dying for a drink, it is starving. If it remains wilted long enough it can die or be slow to recover.

Heat stress can also trigger leaf drop as the plant desperately try’s to diminish evaporation points and conserve its core water. An umbrella placement here may be cooling and shading enough to halt that process. Watering revives wilt, but some cooling is required to stop the other heat stress such as leaf and blossom drop.

Helping your plants survive the excesses of summer heat

The productive gardener has more to contend with in hot weather, as it can decimate crop yields and harvest potential. Fruits are the result of fertilised flowers, so if we lose flowers to heat-triggered drop, then our crops later in the year will be drastically
affected — so we need to put tomatoes, beans, peas, cucumbers, squashes and pumpkins on our radar, as these exhibit a high tendency to drop in higher temps or over prolonged drought.

Blossom End Rot becomes more prevalent in hot weather and in particular with tomatoes, peppers, and squash. BER is more a cultural disorder allied to a mineral deficiency that develops when a plant’s water intake is insufficient or its growing media too sodden — both factors inhibit calcium uptake.

What happens is that half way through their development, stressed fruits develop a smallish water spot at their blossom end which soon darkens and may enlarge rapidly to encompass as much as one-third to half the entire fruit surface.

These blackish lesions then dry out and become flattened, sunken leathery pits. While the rot is not transmittable from plant to plant, or even from fruit to fruit on an individual plant, it does render the affected fruit inedible. The problem is physiological in nature so fungicides and sprays are useless. The chemical treatment is Calcium carbonate added to the water supply or into the growing media. The organic way is also to add calcium supplement. Boiling an egg (without salt) releases calcium from the shell into the boiled water, once cool that cooking water can become enriched and the shells will breakdown and add calcium into the soil too, for next year’s drought.

The main bane to the productive gardener with strong summers is bolting — where the plant or even an entire crop starts flowering early and generally runs to seed. This has a tendency to not just stop the productivity of the plant prematurely, but it can trigger a bittering up of the plant’s taste. Lettuces and many salad crops are quick to bolt with heat and I like to grow them in partial shade to avoid that tendency.

With other green, leafy veg, prolonged dry soil will encourage bolting. Take caution with cauliflower, kale, spinach and rocket. Beetroot is notorious for it and onions (especially red ones) can succumb too. There are ‘bolt-resistant’ cultivars of most veg and as climate change keeps on, we will become more dependent on those.

Climate change can also mean a summer of heavy rain. Those torrential downpours can damage our crops. Too much water can suffocate roots and prevent nutrient uptake, too much can also leach minerals out of the soil and leave little to be absorbed. I love a summer shower, it’s one less chore. But a wet summer is less than helpful.

This year we have already had some battering rains over the summer months and it can bruise and tear the foliage of plants growing in a season where rains are supposed to be failing more lightly.

Helping your plants survive the excesses of summer heat

Most plants engage their flexibility in the face of weight rain — bending rather than breaking and ready to bounce back — there’s a resilience life lesson in that. Don’t be in a rush to go out and prop them back up. Give them time to resolve themselves. They will perk up in a day or two. Then you can remove any damaged foliage to avoid disease vectors. If stems have been damaged, then the secateurs may be called for, but don’t despair, you will have lateral shoots in a while.

Organically grown plants are much sturdier than fertiliser fed plants, and so withstand the rain better. They also withstand the heat and other summer stress better too.

Come autumn, top dressing or digging in some humous and well-rotted manure is the best way to support your plants and crops for next year’s issues.

Fiann’s tips

- Continue to lift potatoes and onions.

- Harvest cabbage, carrots, lettuce, peas, garlic, beets, and spinach.

- Remove ‘finished’ crops and ready ground for next rotation.

- Veg that can be sown now; include radish, spring & winter cabbage, endive, lettuce and broccoli.

- Plant new strawberry plants and tidy old ones after fruiting. Now is the time to pot-up previously layered strawberry runners

- Tip pinch tomatoes and trim some foliage to help ripen fruits. If you have some comfrey liquid feed, feed tomatoes and other vegetables that fruit, if you don’t make a bucket brew of all the weeds you pull this weekend.

- Time to set some yellow sticky traps. Aphids are drawn to yellow as are carrot fly and fruit damaging wasps.

Garden notes

John and Eithna Howard, Seamount, Currabinny, Carrigaline will open their garden today and tomorrow, from 12 to 4pm. The garden was the winner of the Carrigaline Tidy Towns Garden 2016. It is signposted from Carrigaline. Donations welcome. Teas/coffees available. All proceeds in aid of the Cystic Fibrosis charity.

Bumblebee and butterfly monitoring workshops take place on Tuesday and Wednesday next week, August 15 and 16, at the Secad offices in Midleton Community Enterprise Centre. The workshops start at 10am and its open to the public. According to Secad’s Finbarr Wallace: “Irish pollinators such as bumblebees (and solitary bees, the honey bee and hoverflies) have suffered a major decline in numbers over the past few decades. Butterflies in Ireland are also under threat.
“We need to take action to help them and in order to do this effectively, we need to monitor them. That way we can see where there are good and bad locations for pollinators and if the actions we take to help them are working.
“Monitoring is easy to pick up and invaluable to carry out so come along to our workshops and find out how to do it. We highly recommend attending both workshops, but if you can only make one that is absolutely fine,” he said.
Search online for Secad or go to for a map. The workshops finish at 4pm. Midleton train station is located nearby and Midleton is served by a number of bus routes, or there is parking in the business park for those travelling by car. Secad has recently re-branded its Biodiversity Projects section as Wild Work. Have a look at the video at

On Saturday, August 19, Griffin’s Garden Centre is holding a Bee Friendly Bulb Day which will include free workshops all day from 11am to encourage children to start planting. Each child will also get to carry home their free pots filled with bulbs, to nurture over the months and admire in spring. Throughout the day there will be face painting, prizes and lots of fun. There will be a Meet the Beekeepers slot with guests and an observation hive. This is the best way to see honey bees at work and it runs from 12:30 to 3:30pm. Cork Nature Network will be on hand to give advice about pollinators and bees from 1pm to 3pm and to show the importance of pollinators to Ireland’s countryside and natural heritage.

Fitness and wellbeing activities for all the family take place on Sunday, August 20, at the Regional Park in Ballincollig, Co Cork as part of National Heritage Week. This festivalis the first of its kind in Cork and is supported by Cork County Council Physical Activity and Wellbeing Office.
Fitness classes, inspirational talks, foraging and mindfulness walks, yoga classes, good local food, tai chi, pilates, zumba and high intensity training are part of the fun and there will be a designated kids’ area where they can enjoy yoga, zumba, mindfulness and other activities.
Celebrities and local elite sports people will be in attendance, including Olympian Sanita Puspure, former Cork footballers Juliet Murphy and Pa Kelly, and Sinead Kane, the first Irish female to run seven marathons on seven continents in seven days.
Neil O’Brien and Gerry Hussey, both performance psychologists and coaches to elite Irish athletes, will take part in workshops and panel discussions on nutrition, mental fitness, resilience and positive psychology.
Entry is free. Additional car parking facilities will be provided on the day.

To celebrate 30 years in business, DJ Murphy’s garden centre in Bandon is offering 30% off all stock for the month.


Mulranny, in the shadow of the Nephin Beg Mountains on the north shore of Clew Bay, is a hill-walker’s paradise.Old Irish goats deserve to be nurtured

In awe of nature’s bounty on a glorious September dayIn awe of nature’s bounty on a glorious September day

Rotten by name but certainly not by nature.Islands of Ireland: Rotten to the core

There’s a revealing story well told by the writer Alice Taylor about the day a neighbour gave a present of a poached salmon to her family.Alice’s salmon of knowledge

More From The Irish Examiner