A Heat Wave Survival Plan for You and Your Garden .....

Oh Boy it's been HOT ! 

We humans and our plants have all been suffering in this heat, so we thought now is the perfect time to share some of our top tips to help you and your plants survive and maybe even thrive in this or any future heat wave.

Firstly, as any gardener will know, you have to take care of yourself whilst you are working outside in the heat. 

  • Slap on some suncream, wear light-coloured loose fitting clothing - maybe invest in a stylish, wide-brimmed hat and pop on your sunglasses.
  • If possible garden either early in the morning or in the evening once the temperature has started to decrease OR find yourself a cool shady spot to work in and don't overdo it.
  • Drink plenty of fluids
  • Avoid dealing with Euphorbia and other plants which may irritate your skin - their effect may be heightened in the heat and bright sunshine
  • If you or someone you are with seems to be suffering from heatstroke make sure that you follow NHS advice! 

Secondly, you need to develop a survival plan for your flower borders. 

Careful planning will save you both time & money.   If you have a border which bakes in the sun then pick plants which enjoy being baked - Bearded Iris, Nerine, Amarine .... 

Plants have developed their own survival strategies for dealing with heat, many of these strategies are easy for us to spot -  silver leaves which reflect heat, hairy leaves which reduce water evaporation, very narrow or tiny leaves, succulent foliage etc.  all of these adaptations are designed to reduce water loss from the plant by decreasing the rate of transpiration. 

 Transpiration is by definition  "The loss of water vapour by plants to the atmosphere. It occurs mainly from the leaves through pores (stomata) whose primary function is gas exchange. The water is replaced by a continuous column of water (and dissolved nutrients) moving upwards from the roots within the xylem vessels. the flow of this column of water is known as the transpiration stream which is maintained by root pressure and a combination of cohesive and adhesive forces in the xylem vessels according to the cohesion-tension theory"  Reference - Oxford Dictionary of Biology

Some water and nutrient conserving adaptations are less easy to see but are just as effective, familiar examples might be the deep tap roots of members of the Carrot family or the stem tubers of Potatoes - by choosing plants which have an in-built ability to thrive or just survive in the heat we can ensure our flower borders will still be looking good as the mercury within our thermometers nudges its way upwards towards 30oC and occasionally beyond. 

 Prepare the ground properly before you plant, add plenty of organic matter, well-rotted manure or garden compost, during spring or autumn. This will not only feed your plants, it will improve the soil structure which in turn will help maintain soil moisture. Admittedly some soils are endlessly greedy and it may take years of adding organic matter before you have the soil you desire - mulching is the easiest way to improve a very poor soil. Applying a layer of mulch in the spring when the soil is moist will help prevent water from evaporating from the soil surface later in the year and it will improve your soil structure without you having to do any digging.  Be careful not to bury the crowns of your herbaceous perennials with mulch as this may cause some plants to rot. 

Don't plant during a heat wave !  Plants which have been grown in pots can be planted at any time of year but ideally wait until there has been a significant amount of rain and remember to soak the root system of the plant prior to planting by dunking it in a bucket of water. Another one of Rosy's top planting tips is to pour a watering can full of water into the planting hole, allow the water to drain away and then plant.

Do keep newly planted plants watered during hot weather - soak the ground well every couple of days, either early in the morning or in the evening when it's cool, until the plants are well established or the weather cools down and it rains - don't sprinkle the water on the leaves in hot weather as this will scorch the foliage. 

Be prepared for a hosepipe ban by installing rainwater butts  -  check your local water supplier's website for current information on hosepipe bans and if a hose pipe ban has been imposed in your area use grey water to keep your pots and planters going. Prioritise plants which won't survive without water don't be tempted to try and water the whole of your borders or grass. 

When it is so hot that some of your perennials look as if they would be more at home in a hay field, then it's time to take some remedial action. Cutting your plants back may feel wrong but most herbaceous perennials will  bounce back happily - by reducing the foliage and therefore the total leaf surface area you are reducing the plants rate of transpiration and improving their ability to survive. 


A Few Herbaceous perennials which once established will thrive in a hot and sunny border .

Acanthus  - deep roots help Acanthus to survive drought conditions, once planted this tough perennial will be difficult to get rid of so pick your site carefully and then enjoy this plants architectural beauty.  
Achillea - narrow leaves reduce transpiration, notably Achillea 'Moonshine' has narrow, silver-grey foliage. 
Anaphalis triplinervis AGM  - reflective silver grey, hairy leaves reduce transpiration 
Artemisia ludoviciana 'Valerie Finnis' grey, hairy leaves reduce transpiration
Artemisia 'Powis Castle' - small grey leaves minimise transpiration
Aurinia saxatilis AGM  - grey, hairy leaves reduce transpiration 
Centaurea montana grey, hairy leaves reduce transpiration , cutting plants back to ground level after flowering will encourage fresh foliage. 
Dianthus  - Narrow silver leaves reduce transpiration. 
Euphorbia myrsinites AGM - Narrow silver leaves reduce transpiration. 
Geranium ‘Johnson’s Blue’  Or ' Geranium 'Rozanne' - cutting plants back to ground level after flowering will encourage fresh foliage. 
Gypsophila - Narrow silver leaves reduce transpiration. 
Helictotrichum -  Blue Oat Grass, loves a free-draining sunny site.
Hylotelephium spectabile (syn. Sedum spectabile) - Fleshy leaves are well adapted to cope with long periods of drought.
Lychnis coronaria - grey, hairy leaves reduce transpiration
Iris germanica cultivars (Bearded Iris) - these Iris have rhizomes which love to be baked in the sun. 
Kniphofia - deep fleshy roots and narrow leaves make Kniphofia the ideal choice for dry gardens.
Nepetacutting plants back after flowering or once they start to look scruffy will encourage fresh foliage. 
Stachys byzantinagrey, hairy leaves reduce transpiration . 
Stipa tennuissima - a fantastic grass for a free draining soil in full sun
Verbena - narrow leaves have a small surface area to reduce transpiration.
There are many more plants to choose from, but by now you should be well equipped to pick out plants to suit hot, sunny sites - enjoy!!!
The Hardy's Team. 
IF YOU have a handy tip to cope with this excessively hot weather and you would like us to share it on this page please feel free to email us - [email protected]  We will of course credit you with any suggestions given. 
IF YOU have *any topics you would like us to cover in our Newsletter please do email us - [email protected] 
*OK,  just to clarify the statement above when we say  "any topics"  we mean anything connected to growing Herbaceous Perennials.