Plot Troubles – A Dose of Double Desiccation

Manchester, a city not exactly renowned for its Mediterranean climate, doesn’t seem to have had more than a drop or two of rain for at least the past fortnight (rainchester.com says three days, but they’re obviously not checking here in Prestwich).

Down on Plot #59 we’re experiencing a period of Double Dessication, as the ground bakes under the drying effects of both sun and wind. As the state of our over-wintered leek bed demonstrates, the soil is in a pretty poor state just now:

Those same cracking, crumbling, dusty conditions are replicated right across the plot. However, as you can see from the dark area in the centre of the pic where a couple of leeks have been harvested, the soil about four or five centimetres down is still reasonably dark and moist.

This is the ‘dust mulch’ effect in action: the surface tilth has desiccated to the point where it’s too dry for any more water to evaporate out of it, and too dry even to wick up the moisture from the soil beneath. In effect, it creates a protective layer that actually helps to preserve moisture below.

But still, these sort of conditions are obviously far from ideal, and they do have a number of implications for the work that ought to be going on at this time of year:

1) Minimise Digging and Deep-Weeding

Except for non-growing areas like paths, it’s a really bad idea to dig the soil when the weather is dry, as you’ll just expose the moisture that is in the soil and accelerate its evaporation.

Likewise, there’s little point in trying to dig out perennial weeds when the ground is baked hard. Aside from exposing moist soil, you’re far more likely to snap the tap root and leave a chunk of it stuck deep in the ground to re-grow at a later date. Do keep on top of removing seed heads though; dandelions in particular will be going to seed like crazy right now.

It’s fine to hoe off surface annual weeds as well, as long as you’re not exposing too much of the darker soil in the process. Larger weeds can be removed, and weed seedlings will quickly dry up and die, then rot back into the soil when it rains again.

2) Maintain Regular Irrigation

Note, ‘regular’ rather than ‘frequent’. Plants that are rooted in the ground will benefit more from a longer, deeper soak every few days, rather than a light sprinkling once a day or so. This will allow the water to soak into that dust-mulch protected region, and encourage the plant roots to grow deeper in search of it. You’ll also save yourself time and back-ache.

Container-grown plants are of course a different case entirely and will need to be irrigated much more often. If the growing medium in a container dries out too much it can be almost impossible to re-moisten it just by watering. You’re better off standing them in a bucket or tray of water and allowing it to soak back in gradually, rather than wasting water that will just run right through or off the dry soil.

3) No Direct Seed Sowing

Seeds need both heat and moisture to germinate successfully. It’s the uptake of moisture into the seed that triggers the initial development of root and stem, and a steady supply of moisture is needed to swell the cotyledon(s) – the initial ‘seed’ leaves – and to carry nutrients from the soil throughout the fast-growing seedling.

Sowing into a medium that’s a quagmire one minute and then back to dust half a day later won’t do seedlings any good at all. Combined with the scorching effect of sun, the blasting effect of wind and the damage done by heavy drops of water from a can or hose, it’s a recipe for a distinct lack of success. Far better to start seeds off indoors, in modules or trays, and then transplant outside when soil conditions improve.

Fingers Crossed

The forecast here in North Manchester is for rain showers from Friday through the weekend, but it’s set to turn dry again next week. And we’re going to need a bit more than a few showers to restore the soil and re-fill the water butts. Here’s hoping we don’t end up with a full-blown Spring drought on our hands.

How about you? Are you experiencing similar conditions, or have you been pleasantly drenched recently? Feel free to let me know (and in the latter case, make me jealous) via the comments.