Water and the lack of it will be of concern to all gardeners while this hot weather continues. I’ve seen a couple of myths trotted out already and I haven’t really been looking.
Water droplets on foliage do not act as a lens causing scorching. This is nonsense and can be safely ignored. Not that watering the foliage is necessarily a good idea as it can damage the leaves of some plants and increases the risk of fungal disease in others.
I saw a recommendation to hoe the soil surface to create a dust mulch and break the capillary action bringing water to the surface. It seems unlikely that this would be effective. Once the top inch or two of soil is dry it will act as a mulch and there will be little or no movement of water upward through it. Besides, with good crop cover almost all the water loss will be by transpiration through the plants, with almost none lost by evaporation from the soil surface.
My own observation when we had about an inch of rain on Sunday after two weeks of hot dry weather was that recently cultivated soil retained the water and that undisturbed dry ground remained largely dry, having become rather water repellent. I took that to mean that the loose soil retained most of the rainfall at the surface where it quickly evaporated whereas elsewhere it made its way down through cracks and worm holes to a greater depth where it would be less likely to evaporate. It would have to go very deep indeed to become unavailable to plant roots, which will go down several feet.
By the same token, mulches that absorb moisture are going to be less effective than those, like pebbles, that let it all through into the soil.
I have often read that little and often is the worst way to water, wetting only the soil surface and encouraging roots to be shallow and very vulnerable if the watering stops. I agree. I think I would add that if a plant is allowed to become a little stressed between waterings that it will toughen it up and make it less susceptible to drought. A plant that is always kept well watered will grow lush with big soft leaves and will be susceptible to drought whether or not it has been watered correctly. Some things, like cucumbers, hate being dry and may well die if allowed to get to wilting point.
When I water plants in the ground I do so with a watering can without a rose, watering just at the base of the plant or at most in a narrow line along the row. I pour sufficiently slowly that the water penetrates and doesn’t go running off away from the plant. Sometimes that means pouring a little, stopping until the water has gone, pouring a little more, waiting until it’s gone and so on. Sinking a cut off bottle or pipe into the soil and watering into it would be even better but is not practical on an allotment.
I harvested my peas today. Second sweep, I did the first two days ago. I’ve never been able to get them picked and cleared in so short a time, they normally come ready over a couple of weeks meaning if you do it too early many are not ready and if too late a lot are hard, dry and mealy. This year almost all were spot on.
I suspect that up country, where the mid summer climate is more reliably dry and warm, that what I have this year is the norm, with the occasional cool damp summer leading to what is the norm in Cornwall. The trouble with gardening books and online advice is that they usually reflect average conditions, not marginal conditions. This year it would be easy to get a second crop in after the peas, in a cooler year it would be pushed back by a couple of weeks and it would be likely that it would not have enough growing season left to succeed. It depends what you try to grow, I hear you say.
Well yes, which is why I have just planted lettuce (that’ll work) and beetroot (that may not) and have Purple Sprouting broccoli, cabbages and kale still to go in.