Thursday, 12 July 2018

Hot Weather Watering: Part 4: Resuscitation

Earlier this week I started a short series on Watering in Hot Weather: the other pages being...

1: General Principles.
2: Don't waste water on plants that don't need it
3: Pots

Today, last in the series (unless I think of something else to add), Part 4: Resuscitation.

What to do  if you've left it too long, and the plants are wilting....

In the Garden:

Well, obviously, get out there and water it, even if it appears to be horribly too late: it constantly amazes me how plants will recover from what appears to be certain death.

There's a three-letter acronym they use in the RHS Level 2 course: PWP. It stands for Permanent Wilting Point. (Honest! No joke!)

If a plant has reached PWP then it can't recover, and is dead.

But there is a whole spectrum of conditions before you get to that point - differing degrees of wilting, if you like. So it's always worth watering and waiting, just in case...

You can help by roughing up the surface of the soil around the plants: often, soil will form a pan or crust on top, which prevents any water from getting down to where it can be useful, ie around the roots of the plants. Break up the surface of the soil with a hand-fork or a daisy grubber, aiming to make the top couple of inches penetrable.

If the soil is like concrete, stab downwards with the hand tool, to make vertical holes: they will then fill with water next time you get the hose out, and will act as little sumps, to hold the water down below the surface. Eventually, the sides of all these sumps will soften and crumble, allowing water to penetrate more freely.

Soil pans (or crusts) are often worse where people hoe, rather than weed: a hoe tends to create what looks like a fine tilth, but is actually a shallow layer of dusty soil on top of a hard pan, neither of which is good for the soil or the plants. So if you are in the habit of hoeing, check that your soil is still open and crumbly by trying it with a hand-tool.

With regard to trees and shrubs, they will drop leaves if stressed by lack of water, then grow new ones when water becomes available. So if you find brown, crispy leaves on plants, don't expect them to miraculously turn green again. If the brown or black leaves are willing to drop off when you gently shake them or brush a hand through them, then remove them, rake them up and dispose of them.

But don't pull off dead leaves which are reluctant to fall - don't force them, as you might damage the bud at the base of the leaf, and that's where the new leaf will grow from. Once the new leaf appears, the old one will fall of its own accord.


Next time you are about to water, push your fingers into the soil around the plant(s), if it's loose enough. Is it dry and dusty? Pour on a slosh of water, wait for it to disappear, then push your fingers in again. Is it still dry and dusty, and has the water all gone, leaving the soil miraculously still bone dry?

This is the problem with shop-bought compost: it is very hard to re-wet it.

There are two ways to re-wet compost: either you have to submerge the whole pot in a bucket of water, holding it under until it stops bubbling (resisting the urge to snarl "Give me the secret codes, you swine"), then leave it for at least an hour: or you have to manually push the water into the compost by rubbing it through your hands in the manner of someone rubbing up a crumble.

(For anyone under the age of about 40, or anyone male, much of baking involves mixing fat and flour together. Stirring doesn't do it, you have to get in their with your bare hands and rub them together between fingers and thumb,  using a rub-and-lift action repeatedly, until the mixture resembles fine breadcrumbs.  [At this point, I'm wondering how many people under the ago of about 40, or male, don't even know what fine breadcrumbs look like..]  Wetting compost requires a very similar action, and takes about the same length of time. I'm sure there's a video on it on yootoob somewhere...

... good lord, there is indeed, it's right here.)

So if your pot's soil is like dust, pour on some water and get your hands good and muddy, rubbing the water into the soil until you get mud. Go as far down into the pot as you can - this will depend on how full of roots the pot is. Once the soil is rewetted like this, you will be delighted to see that future waterings no longer flood straight through and out from the bottom.

Soaking is easiest, in the sense that once you plop the pot into water, you just go away and leave it: but it only works with pots small enough to fit into a bucket. And you might have to weigh down the pot, to stop it bobbing around on the surface.

For larger pots, especially heavy terracotta ones, all you can do is place them on the deepest saucers you can find, as per part one:  water them until the saucer fills, give it time for that water to soak back up into the pot, then keep adding more water to the top, until you reach a point where you can water the top without it immediately flooding down into the saucer. This indicates that you have managed to soak at least some of the soil within the pot, hooray!

Leave them sitting in their saucers until the hot weather is gone.... it won't be long, I'm sure.

If you  have a large number of smallish pots: seedlings perhaps, or cuttings, then a soaker box is a good way to do it: take a plastic tray or box or container (or a cardboard box lined with plastic, ie a bin liner, or a compost/bark bag), fill it with a couple of inches of water, and stand the pots in it. Pour more water onto their tops and leave them to soak for a while.

Here's my soaker box at home - left. It's a plastic greengrocers' vegetable tray lined with a compost bag (no expense spared, for us Professional Gardeners!).

As you can see, I use it for individual pots which have dried out too much, and for trays of smaller 9cm pots.

They get plunged, and allowed to soak it all up: and if they are looking a bit pale and wan, I add some liquid seaweed feed to the water in which they are soaking.

The piece of wood top left, in case you are wondering, is a ramp to help my frog get out with dignity... here's a close-up of the top of the picture:

Yup, that's my little froggy pal, the reason why I have snails in my front yard, but no slugs.

Good boy, froggy! He seems to think my soaker box is his own private pond, but I don't know what he thinks about the times when I add the seaweed....

As with the garden advice, I'd suggest not being too quick to prune the plants, unless there are sections which are clearly and obviously dead: if in doubt, give it a chance.

Having said that, with perennials, you can certainly crumple off any paper-dry foliage, as it is unlikely to recover: but in general, I would say leave them for a few days, to see if they pick up.

And finally, don't stop watering just because the sun goes in one day, or if we have a light sprinkling of rain: keep on watering until we get proper, drenching, British-summer-rain again. It won't be long!

If you missed any of the other articles in this series, you can either go back through the archive list, or jump:

1: General Principles.
2: Don't waste water on plants that don't need it
3: Pots
4: Resuscitation (this one) 


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