Thursday, 29 January 2009
Keeping Our Plants Alive During the Heat
I've been thinking a lot lately about how we can keep our gardens going and keep producing food during the hot weather we've been having.
Maybe the main culprit is not the heat but the dryness of the air? Certainly here, the humidity is usually close to zero during the summer heat and the air seems to suck the moisture out of everything.
The beans form nicely on the climbing bean plants, but they almost dry on the bush before they are fully developed. The plants look fine and are mulched and watered, but the air is so dry it dries out the fruit as it hangs on the plant.
So, I've been trying to think of ways to reduce the evaporation from my plants. Things like the old sheet canopy I put over the carrots to get them to germinate or possibly some sort of shade tunnel that could also be used to ward off the first few frosts? Or get the food forest thing happening in the orchard . . .
Then last night I was visiting Molly's blog and she had a post about some online resources. Adding to my heat-induced sleep deficit (yawn!), I decided to pay the site a visit. I found an article by William Albrecht which claimed that the absence of water was not what damaged plants during drought, but the fertility and depth of the soil. That is, plant hunger, rather than plant thirst!
Dr Albrecht's basic argument is that if soil is prepared and made fertile to greater depths than used in conventional agriculture that the plants will use the available water in the soil more completely and more efficiently. He cites experiments to support his theory.
Interestingly, the vegie bed that is best surviving the heat at my place is the one in which I grew the oats last winter. The oats left the soil in a very fine tilth, although not that deep. Because I thought the oats might have taken out a lot of nutrients, I gave that bed twice the amount of manure that I normally do. I also gave it a good dig over to distribute the manure. This bed is planted up fairly densely with sweet corn, tomatoes and rockmelons and is coping much better than the maize in the next bed.
The other bed still coping very well is the asparagus bed, which I heavily manure twice a year and give the odd dose of seaweed extract and fish emulsion. The asparagus are barely fluttering a fern with the heat.
Well, it could be canopy cover - both of these beds have good leafy coverage. But so do some of the other beds. It could be the plants, but the same plants in other beds are not coping nearly as well with the heat. It could be the mulch, but most of the other beds are mulched as well, if not better. And, if anything, the maize bed gets more water than the sweet corn bed and certainly more than the asparagus bed.
So, maybe William Albrecht's studies have something to show us - prepare the soil well and deep to maximise fertility and the plants will survive. It's certainly made me think about doing much more preparation in the garden this winter to try to build the humus and soil fertility.
Which brings me to another point. In naturopathy, we talk about a person's vitality. The theory is that the more vital the person (physically, mentally, emotionally, spiritually), that the more likely they are to be resistant to disease and the more resilient they are likely to be.
Surely the same must apply to our gardens. We can't stop the heat, but maybe we can build our gardens to be more resilient to it.
Forecasts about climate change are predicting temperature rises of 0.4C to 2C by 2030, with more hot days over 35C.
This means we need to build our gardens to be able to cope with more summers like this one. I'm going to be putting some serious thought into this and I would love to hear any ideas you may have about how we can help our plants survive. I'd also love to hear if you have some areas of your garden surviving the heat better than others and what the differentiating factors might be.
love and light