How to keep flower beds alive through a heatwave

Keeping flower beds alive through a run of hot days

A flower bed can look perfectly happy on a Wednesday and be half dead by Sunday, and the difference is usually a few small things done or not done in the days before it got hot rather than anything heroic done during. Here is the list, roughly in order of how much difference each one makes.

1. Mulch, and mulch properly

A thick layer of organic mulch, bark, straw or compost, cuts the water lost off the surface, keeps the soil cool underneath and holds the weeds down while it does it. It also feeds the bed as it breaks down. Go 5 to 7 centimetres and keep it back off the stems. Nothing else on this list does as much for as little effort.

2. Water deeply and less often

A light sprinkle every evening trains the roots to sit near the surface where they cook. A long soak twice a week sends them down where the soil stays damp. Early morning is the best time for it, because the water gets into the ground before the day heats up, and the leaves are dry again by night, which keeps fungal problems down.

3. Shade the ones that will not cope

Some flowers are simply not built for full afternoon sun in a heatwave. Impatiens and fuchsias are the obvious ones. Shade cloth over the bed for the worst few days is fine and nobody is judging you, and planting a taller sun lover on the western side of them is the permanent version of the same idea.

4. Deadhead and prune as you go

Taking the spent flowers off stops the plant putting energy into seed and keeps it making new buds instead. Thinning out the crowded growth at the same time lets air move through the plant, which is most of what keeps mildew and rot out of a bed in humid weather.

5. Go easy on the fertiliser

This is the one people get wrong with the best intentions. A plant already stressed by heat does not want a big feed of nitrogen, because you are asking it to grow soft new leaf at the exact moment it cannot support it. Slow release or compost is the right answer through the hot part of the year, and the heavy feeding goes back on when it cools off.

6. Watch for pests, because they turn up fast

Aphids, caterpillars and spider mites all get going in the heat and a stressed plant has less in the tank to fight them off. Have a proper look under the leaves once a week rather than waiting until something is obviously chewed, because it is a much smaller job caught early.

7. Plant more of the things that were never going to struggle

Lavender, kangaroo paw, salvia and the native grasses are all doing the same job as the fussy stuff with a fraction of the water. Every one of those you put in is one less plant you are nursing through January.

8. Keep an eye on the soil itself

Heat pulls moisture and nutrient out of soil quickly, and a bed that has been growing hard all season is usually poorer than it looks. Working organic matter through it is the fix, and it is the sort of job that pays you back over years rather than days.

9. Cut a struggling plant back rather than watching it

If something has gone crisp and sad, cutting it back hard takes the load off the roots and very often brings it back. It looks brutal for a fortnight and then it is away again. Leaving it to limp along usually finishes it.

10. Group plants by what they drink

Put the thirsty ones together and the dry ones together. It sounds like a design detail and it is actually the thing that stops you either drowning the lavender or letting the petunias die, because one bed can only be watered one way.

Shop related products

• Easy Wetta Garden Mulch 50L. Bagged mulch for beds and borders, and the first thing to do on this list.
• Martins Organic Sugar Cane Bale 11KG. Light bale mulch, easy to spread over a whole bed in one go.
• Go Go Juice 1 Litre. Liquid tonic for a bed that has been knocked around by the heat.
• Seamungus 500g. Gentle seaweed and fish based conditioner, the right sort of feed for hot weather.
• Brunnings Garden Compost with Seaweed 25L. Organic matter for a bed that has been working hard all season.

There is Pope irrigation for anyone sick of standing there with a hose, a pest control range for the aphids and caterpillars, and the rest of it in the garden range online. Come and have a look through the garden centre if you want a hand working out what suits your bed.

Read next

• Setting up dripper irrigation, a beginner's guide
• What is the cardboard weed barrier method?
• How do I plant a tree?

Every summer I promise myself I will mulch in October instead of January, and every summer is a fresh chance to find out.

Candeece

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