When the sun is blazing and temperatures soar, as we’ve seen unexpectedly in the UK a few times already this year, your garden needs a little extra TLC. Knowing how to water plants in summer can make all the difference between a thriving, colourful space and one that’s dry and drooping. In this guide, we’ll explore heatwave gardening tips, how to keep your plants hydrated, and when and how often to water for the best results.
When is the Best Time to Water Plants in Summer?
One of the most common questions is, “When should I water my garden in hot weather?” The answer is: early morning or late evening.
Morning (before 10am): This is ideal. The soil can absorb the moisture before the heat of the day sets in, and any splashed leaves have time to dry (reducing the risk of disease).
Evening (after 6pm): If mornings aren’t an option, this is your next best bet, just avoid soaking foliage overnight, which can encourage mildew.
Avoid watering in the middle of the day, when the sun is strongest, as most water will evaporate before it reaches the roots.
How Often Should You Water Plants in Summer?
There’s no one-size-fits-all answer, as it depends on plant type, age, soil, and weather conditions. But here are some guidelines:
Containers and hanging baskets: Daily watering is often needed, especially in direct sun.
New plants and seedlings: Water every 1–2 days until established.
Established plants and shrubs: Water deeply 1–2 times per week to encourage deep root growth.
The key is watering deeply and less frequently, this helps plants grow resilient roots that dig deep into the soil rather than relying on surface moisture.
What to Look for: Signs of Thirsty Plants
Plants that need water might show:
Wilting or curling leaves
Soil pulling away from the edges of containers
Pale or scorched foliage
A dry, dusty soil surface
Keep an eye on soil colour too. Dry soil tends to appear lighter and dusty, whereas moist soil is darker and clumps together when squeezed.
Top Tips for Retaining Moisture in the Garden
Keeping your soil moist for longer is key during the summer. Here are some easy wins:
1. Use Mulch
Adding a layer of mulch – like bark chips, straw, or compost – helps retain soil moisture, regulate temperature, and suppress weeds. It also adds nutrients to the soil as it breaks down. Mulch is best applied in the spring and autumn.
2. Choose Moisture-Retaining Compost
For pots and raised beds, look for composts enriched with water-retaining granules or mix in additives like coir, vermiculite or water-storing crystals. If you’ve got particularly sandy soil that dries out extremely quickly, adding compost can help amend your soil and help it to retain more moisture in the future.
3. Install Self-Watering Systems
If you’re going away or want to make life easier, self-watering planters or slow-release watering globes are a great investment. You can also run a soaker hose through beds to deliver moisture directly to the roots.
4. Group Plants by Watering Needs
Place plants with similar water requirements together; this makes watering more efficient and avoids over- or under-watering certain varieties. Grouping plants together also creates shade and reduces moisture loss.
5. Water Thoroughly
If you notice that water runs straight through the bottom of a container or pools on the surface without soaking in, the soil is likely too dry and has become hydrophobic (water-repellent). When this happens, water can’t easily penetrate the surface, meaning your plant isn’t absorbing what it needs.
To fix this, break up the top layer of soil gently with your hand or a small tool to help the water sink in. Water slowly and in stages, allowing each small amount to absorb before adding more. This prevents runoff, conserves water, and ensures your plant gets a thorough drink.
Heatwave-Proof Plants
If your garden regularly sees high temperatures, or you often simply forget to give the garden a good water, consider choosing more drought-tolerant species like:
Lavender
Sedums
Echinacea
Rosemary
Agapanthus
These plants are built for sunshine and can handle drier spells once established.
Watering your plants in hot weather isn’t just about dumping on more water, it’s about timing, technique, and knowing your garden. With a few smart adjustments, you can help your garden thrive all summer long, no matter how high the mercury climbs.
Don’t forget, at St. John’s Garden Centre, we stock everything you need to keep your garden flourishing in a heatwave, from mulch and compost to irrigation tools and expert advice. Pop in and let our team help you make the most of the sunny season!