Drought Tolerant Gardening- how to garden in a heatwave

We gardeners are known to be obsessed with the weather, but lately the talk has been on an epic scale. With so much hot dry weather working its way across the world, temperatures still soaring and records likely to be set, the chat has quickly moved to drought tolerant gardening. What can we do to make our plants more able to cope in heatwaves?

So I thought it would be helpful to share the advice I’ve gleaned.

Read more: Drought Tolerant Gardening- how to garden in a heatwave

1. Drought Tolerant Gardening – Watering

First up has to be watering. There’s a real tendency to reach for the hose/watering can when we’re in such a dry spell. But this often isn’t necessary, as many plants are tough as old boots and will survive sustained periods of drought.

So a key step to drought tolerant gardening is knowing your plants. That way you can focus your watering where it matters most.

(Huge warning here – I’m no veg grower, sorry I know, I’m a philistine! But I just can’t be bothered to spend time and garden space on veg. So none of my advice covers veg gardening.

Daily/Every Two Days

The plants you will definitely need to water most regularly are seedlings, plants in greenhouses and conservatories, young plants and those you’ve recently planted. Of course you will also need to keep a vigilant eye on your pots. I’m checking mine every day and watering the smaller containers daily. But to be honest that’s what I do most of the time anyway, as I’m very conscious that plants in pots are completely dependent on me for their survival. So the guilt if I get it wrong and one of them dies is unbearable!

If like me you have a tree fern, they are definitely a plant to think about in this weather. My tree fern is tiny and is in a container, grouped in a semi shaded corner of may patio alongside lots of ferns and a banana plant. This creates a lovely, fuggy, micro-climate of humidity but if your tree fern isn’t in an environment like that – or is free standing and bigger – drying out is a real risk. Water its trunk daily, as it needs to maintain humidity.

Weekly

As the name suggests, hydrangeas are water lovers. So keep an eye on them for signs of drooping. In this dry weather I notice that after a week, my line of Annabelle Hydrangeas starts to wilt. They’re growing under the semi-shade of trees. If they were say against a wall in full sun, my hunch is they’d need watering even more frequently. So watch for wilting in your hydrangeas and act when you see it but as a rule of thumb, water weekly.

Two Weekly

In sustained dry periods, some plants in the garden which can normally fend for themselves may need a bit of help. In particular the plants which to my mind are going to a lot of effort to ‘produce a show’ – such as clematis and roses. So give them a really good drink every couple of weeks. I regularly feed these plants too, so you could perhaps do that at the same time. Also water fruit trees which are on dwarfing rootstocks every two weeks.

If you have camellias in your garden remember they have shallow roots. They will also benefit from a water every couple of weeks as part of your drought tolerant gardening regime.

Once established, bearded irises are fine in dry conditions. Indeed mine are happily baking at the front of our cottage. But siberian irises and the iris ensata both like water (hardly surprising given that the latter is also known as the Japanese Water Iris). So I’d include them in your two-weekly regime.

I have a line of tiarellas edging two major beds. I give these a good drink every couple of weeks – when they look really dry and droopy. Other than that everything else in my beds and borders is left to get on with it.

I’m not being cruel. If a plant looks like it is suffering I will of course step in and give it a drink but many plants can cope with sustained periods of no water.

Don’t Water

There’s really no need to water mature shrubs and trees. They will be fine. As will a whole host of plants.

2. Drought Tolerant Gardening – Choose Plants Which Can Cope

Indeed, if sustained periods of dry weather are going to be a future fact of life, it’s worth knowing which are the best drought-resistant plants. There are heaps to choose from.

For instance, without really planning things that way, I’ve found that the following which I already have in my garden are coping very happily with the dryness:

• Gaura
• Periwinkle (almost bomb proof)
• Alliums
• Euphorbia
• Helianthemum
• Nepeta
• Sedum – which is now called Hylotelephium (don’t ask me why!)
• Stachys
• Stipa
• Verbena
• Geums
• Hardy geraniums
• Pittosporum
• Sea Hollies
• Crocosmia (not officially drought tolerant, but mine which grow in a dry bed are fairing pretty well)

Plants which I don’t have but which I’ve also read are great for drought tolerant gardening:

• Aeoniums
• Cordylines
• Agave
• Verbascums
• Star Jasmine
• Cotyledon orbiculata

So a drought tolerant garden can be colourful!

3. Dought Tolerant Gardening – Know How to Water

You want to water with purpose. So water your plants ideally early in the morning when the temperature isn’t as hot. Or if you can’t manage that, choose the evening. The secret is to lose minimal water to evaporation. Water the ground near the base of the plants – not on the leaves. It’s the roots that need the water. And water enough to fully saturate the soil. Watering less often but really fully is much better than watering a little, frequently.

One thing to bear in mind is that in your drive to keep your plants in containers hydrated, there’s ironically a chance you will over-water! So take care with this. Poke a finger into the soil in your pot to see if it feels dry a couple of inches down. If it does, water. Also, alot of thorough watering may actually rinse out a lot of the goodness in your container’s soil. So don’t forget to feed your plants. I feed all my container plants every two weeks with liquid tomato feed during the peak growing season – whether we’re in a hot spell or not.

4. Leave Lawns

If your lawn is like mine, it looks terrible at the moment. More a dry dust bowl than a luscious lawn! However watering it is an absolute waste of time. Established grass, if it goes brown, will recover when the rain comes. So don’t panic. In autumn simply give your recovering lawn a bit of TLC and it will bounce back very happily. I’m really no lawn expert but the BBC has a really good action plan for recovering a lawn in autumn. It’s well worth a read.

Talking of drought tolerant gardening advice, I also picked up a good grass tip from Martine Le Gassick, a creative director at garden design company Stark & Greensmith. She suggests leaving grass longer in a heatwave. Apparently long grass can tolerate the heat better. Leaving the grass taller also helps to retain more moisture in the soil. Try to keep your grass 6 inches during a heatwave. Interestingly, I have accidentally got an area of grass that is this length and it is so much greener and healthier than the short grass next to it. So I can vouch for this advice!

5. Drought Tolerant Gardening – Some Container Tips

I have almost 100 containers. So I’m on serious watering duty with these whether we’re in a heatwave or not! But what other drought tolerant gardening advice is there for people like me with oodles of planters? Again Martine Le Gassick has some good tips which she shared with me:

Mulch

First up she suggests adding some reflective mulch like tree bark or grass cuttings to your planters. Martine argues that mulch protects the roots of plants from the negative effects of sunlight and helps release nutrients into the soil. This will keep the soil cooler and prevent it from drying out.

I can vouch for this tip as I’ve definitely found my hostas in pots – which have mulch called Strulch around them to deter slugs – have coped really well with the heat. Much better than expected.

Avoid Pebbles

Although they can look attractive, Martine warns against filling your planters with pebbles or other inorganic mulches. As these will collect, absorb and hold heat which will cause your plants to wilt and die.

Pot Colour

Also think about the type of plant pots you use. Martine suggests placing your plants in light-coloured pots will help reflect sunlight and keep planters cool. That’s why my darkest coloured plant pots are in the semi-shady area by my back door.

Terracotta or thick glazed ceramic pots will keep potted plants more cool than plastic or dark glazed pots. 

Placement

Martine also provides some useful advice around container placement. She suggests that, if you can avoid it, keep pots and planters away from direct sunlight and be aware that patios facing south or west will be hotter during the summer. I’m definitely following this advice, minimising the number of containers at the front of our south facing cottage at the moment. Those that are there I’m keeping a close eye on and watering more often.

She also warns about putting containers where light is reflected from walls or fences. Planters on gravel or concrete will also absorb more heat and suffer from extreme heat so try to avoid placing them on these. Oh dear – my south facing containers are on our gravel drive – maybe I need to move all of them and rethink my container strategy if I’m trying to achieve drought tolerant gardening in the future!

6. Build in Shade

There’s a real risk that longer-term we’re all going to need to cope with hotter, drier summers. This may require us to rethink areas of our garden. So when planning your garden, try to create areas of partial shade. These will keep your garden cool and protect plants during a heatwave. By semi-blocking the sunlight on plants, the soil will stay cooler and retain moisture to keep your plants healthier for longer. For instance my Catalpa trees are definitely helping my hydrangeas to look super-fresh even in these blistering conditions.

However, you don’t need to go to the lengths of planting trees in order to create shade.

Here are some quick ideas for instant shade:

• Umbrella
• Trellis
• Shade cloth/net
• Quick growing vining plants
• Wigwams of plants
• Pergola
• Sail

Trellises work well to block excessive sunlight. Grow vining plants up the sides of the trellis and you have a quick effective shaded area for the plants below.

Or if you have fixed shrubbery, and want a more permanent drought tolerant gardening solution you could add a pergola to provide filtered sunlight.

7. Weeding

I know that weeding isn’t popular at the best of times, and in the heat it’s not the first gardening job we fancy doing. However weeds are competing with the plants you are trying to look after in a drought. They will soak up the water in your soil, as well as the light and nutrients, leaving less for your precious plants. So weed your garden at least once a week during hot weather.

If it helps on the motivation front, reward yourself with a lovely cool G&T at the end.

8. Collect Water

Lastly, anyone thinking seriously about drought tolerant gardening needs to future-proof against water restrictions and hosepipe bans. That means collecting rain water. Fix a water butt to every rainwater downpipe on your house, shed, greenhouse, conservatory or garage. Even if your garden is small don’t panic, they don’t have to take up masses of space. Slimline models are available for smaller gardens. 

So that’s it! Advice for helping you and your garden cope with the heat. I hope this helps you and your plants stay happy and cool!