Keeping Your Garden Alive in a Peninsula Heatwave
January on the Mornington Peninsula can be brutal. One day it’s a pleasant 26 degrees with a sea breeze, the next it’s 40 and everything in the garden looks like it’s given up. The good news is that most established plants can handle a few hot days if you prepare properly.
Water Deeply, Not Often
The biggest mistake in a heatwave is light, frequent watering. A quick sprinkle every day encourages roots to stay near the surface — exactly where they’ll cook when the soil heats up. Instead, give your garden a long, deep soak every few days. You want water getting down 20 to 30 centimetres into the soil where roots can actually access it.
On the Peninsula, our sandy soil drains fast, so deep watering matters even more here than in clay-heavy parts of Melbourne. If water runs straight through your beds, you probably need more organic matter in the soil — but that’s a job for autumn, not the middle of January.
Mulch Is Your Best Friend
If you haven’t mulched yet, now is the time. A thick layer of chunky mulch — 7 to 10 centimetres — keeps soil temperatures down, holds moisture in, and means the difference between a stressed garden and one that cruises through summer.
Avoid fine mulches that compact and repel water. Coarse bark, chunky tree mulch, or sugar cane all work well. Keep mulch a hand’s width away from plant stems to avoid collar rot.
What to Do on the Day
When a 40-degree day is forecast:
- Water the evening before, not on the morning of. This gives soil time to absorb moisture overnight.
- Don’t water in the heat of the day. It mostly evaporates and can scald leaves.
- Move pots into shade. Terracotta pots especially can cook root systems.
- Leave wilting plants alone. Many plants wilt as a survival mechanism — they’re reducing leaf surface area to conserve water. They’ll often perk up by evening. Panicking and flooding them can do more harm than good.
- Don’t fertilise. Feeding plants in extreme heat puts stress on already stressed roots.
After the Heatwave
Give everything a good deep water once temperatures drop. Check for sunburn damage — brown, papery patches on leaves — but don’t prune damaged foliage straight away. It’s actually protecting the growth underneath from further sun damage. Wait a few weeks and trim off dead material once new growth appears.
Peninsula gardens are tougher than you think. A couple of hot days won’t kill a well-mulched, deeply-watered garden. It’s the neglected ones that suffer.