Heatwave is great for holidays, but not for the soil - gardener Jamie Marsh tells us why

In his weekly Jamie’s Little Allotment column, gardener Jamie Marsh talks about the impact of the ongoing heatwave, and his gardening podcast…

The weather reports are showing we should be getting some decent rain in the week ahead, so by the time you’re reading this, the grass should have started growing again.

I’ve been watching the forecasts for weeks now, and most of the time they predict rain, only for it to change last minute, and we get nothing. If I remember rightly, we haven’t actually had a good amount of rain since March, which is quite scary when you think about it.

It’s great weather if you’re on holiday or planning a day out, but for gardeners and the environment, it’s not such good news. Hosepipe bans are already in place in several parts of the country with more expected this week.

When we get heatwave after heatwave, it’s not just the lack of water that causes problem, it’s what happens when we finally get a decent downpour. It might sound silly but a lot of the soil has become what’s called ‘hydrophobic’ and repels water - it resists absorbing moisture. Instead of soaking in, water beads up and runs off the surface.

Have you ever had a pot plant that’s been left dry for so long that when you finally give it a drink, the water just floods straight out of the holes at the bottom without soaking in at all? That’s hydrophobic soil. The only way to get moisture back into it is to submerge the pot in water and leave it there until the air bubbles stop rising.

There are a few videos online that show this clearly. One shows a test using jars of water upturned on the ground. The first is on lush green grass, the water seeps out quickly into the soil. The second is during a typical UK summer, the water takes longer, but it does eventually soak in. The third is during a prolonged dry spell like we’ve just had, the water stays in the jar as if there’s a lid on it. That’s proof the soil below has become hydrophobic.

The big problem is when rain finally arrives, it often runs straight off the dry ground That run-off builds up fast and can cause flash flooding and we all know how damaging floods can be. So here’s hoping that when the rain does arrive, it comes gently, giving the soil time to adjust.

If you read last week’s column, you may remember I was talking about successional sowing and growing, the process of keeping things going in the allotment all the time. So, when a bed (or part of one) becomes empty, you get something back into it straight away.

I spoke about sowing seeds early enough so that when space becomes free, you’ve got small plants ready. I also mentioned buying plug plants to fill the gaps, which is what I’ve done this week. A lot of them are brassicas, cabbage, kale, broccoli, which will grow through the summer and be ready to harvest in winter and even into spring.

I haven’t had time to plant them out yet, so I’ve popped them in a seed tray and given them a good water. They’ll be fine for a few days until I can get them planted. I’ll show you them next week.

I’ve had quite a few emails with questions and updates about what you’ve been doing the garden, I really enjoy reading them. If you’d like to get in touch, you can email me at: Jamieslittleallotment@gmail.com You can also follow what I’m up to on Instagram: @Jamies_little_allotment

I also do a gardening podcast called ‘Through The Garden Gate’. Have a listen and let me know what you think.