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How to water the garden properly, even in heatwave conditions

How to water the garden properly heatwave hot weather conditions - ArtMarie / E+
How to water the garden properly heatwave hot weather conditions - ArtMarie / E+

Every week, Telegraph gardening expert Helen Yemm gives tips and advice on all your gardening problems whether at home or on the allotment. If you have a question, see below for how to contact her.

There is something undeniably glorious about the fresh, earthy smell of a wet garden. But watering our gardens is not about that, it is all about drenching needy plant roots efficiently to enable their uninterrupted growth, while wasting as little as possible of that most precious resource – water. Ultimately, it’s about not splashing it about.

When should I water the garden?

Early morning is best, however, a lot of us choose to water in the evening, when we may have more time. Avoid the middle of the day – although if a plant is visibly wilting, don’t wait, just give its roots a gentle soak. Take your time and try to be methodical, especially if you grow lots in pots.

How?

Watering cans: Aim the can low, drenching the soil. Especially if you are watering seedlings, use a can with a flat, fine rose, turned over so that the gentle water jets are directed downwards and therefore splash and disturb less.

Hoses, when the water butts run dry: The best way to water with a hose is via a lance (either fixed or telescopic), with an adjustable rose “head” that can be fixed at about 90 degrees to the pole, enabling you to reach between plants and slowly drench the soil around each (see hozelock.com – see also their compact Pico hose, useful for small spaces).

Pegged-down porous seeping hoses (that can be set on a timer) deliver water exactly where it is needed very slowly, and are useful for deep borders and for the establishment of new shrubs and hedges (kits are available from harrodhorticultural.com).

How much?

A hurried swish will merely dampen the soil surface and encourage vulnerable surface rooting. Most likely to suffer are plants in containers in “soft” composts, especially those that are peat-based, as they are really hard to re-wet once dry.

Get to know your plants, as they have different needs: Tomatoes need at least a daily drench in high season, while fussy succulents (like echeverias) hate permanently wet feet and will let you know as much by dying. It pays to do a test (by simply sticking a finger in the soil) with your ground-based plants as well as your pots, and adjust your watering regime accordingly.

Plants likely to suffer most from lack of water are newly planted trees, shrubs and perennials: make a circular gully around individual young trees and large shrubs about 30-45cm from their main stem and fill it with water several times to ensure that roots are kept supplied.

It should now go without saying that we should routinely apply moisture-retaining mulches (that can be scraped away before watering and then replaced).

Other watering issues – briefly

Watering with recycled soapy dishwater or bathwater is fine, but softened water or dishwasher water are not. In the short term, tap water is better than no water for lime-hating rhododendrons and camellias; in the longer term, treating these plants with Sequestrene (chelated iron) will help sort out resulting mineral deficiency problems.

And finally, please, however much you want to… never water your lawn. Grass recovers.

Tip for spring and summer flower borders

Deadheading - Mint Images
Deadheading - Mint Images

Deadhead flowering plants regularly. For aesthetic reasons it is important to take a length of stem with each spent flower (down to a leaf joint or just above an emerging flower stem). Deadheading delays seed-setting and therefore vitally lengthens the flowering season. Couple a deadheading regime with general border inspection, damaged leaf removal and support adjustment. This, in between putting your feet up, is what June gardening is all about.

Why is my rhubarb so skinny?

This year the stems of my rhubarb have been prolific but very thin. I fed it early on with horse manure and chemical fertiliser and watered it well. Have I overdone it?

Sarah Collins – via email

Yes, it does sound to me as though you overdid it with the fertiliser. One or the other would have been fine. Rhubarb produces skinny stems when it is immature – if grown from seed it may take as long as three years before it makes enough stems of suitable thickness that you can “pull” without pulling the whole plant out of the ground.

It also sends up a load of weedy stems when its crown becomes elderly after about six or seven years (in my experience); no amount of generous feeding will fix this. Your picture showing congested stems coming from a chunky crown would indicate the latter case.

I suggest that your plant needs digging up and splitting. This should give it (or the part with several visible growing points that you keep and replant), a new lease of life. Do it in November, when it has naturally died down, and enrich the soil with rotted manure to give it a good start next year.

We expect an awful lot from our poor rhubarb, which is, after all, just a regular herbaceous perennial whose stems we greedily plunder and whose flowers we abhor. Ideally rhubarb should be split while still in its prime.

Why have buttercups  invaded my lawn?

This spring lots of buttercups have appeared in my lawn. They are sprinkled across quite liberally. I have never had this before and I am concerned that they will become a problem in the future.

I am not precious about the lawn and like it to be natural: a few daisies and some speedwell among the grass is fine, but I do not want a lawn full of buttercups!

Heather Mather via email

The invader is creeping buttercup which, as the name implies, is a ground-hugging member of the buttercup family that spreads by surface runners that quickly root. This buttercup thrives in shade (particularly damp shade) where grass struggles and can quickly outcompete it.

The fact that you are not “precious” about your grass and welcome other incursions to a certain degree means that you are going to have to also live with the buttercups and perhaps even learn to love them.

The alternative is to spend time (on a rug, in the sun?) using an old kitchen fork to winkle out some of the runners and the chubby coarse-leaved buttercup “hubs” from which they radiate, to limit their spread. While this may be a fun activity in the short term, it won’t be a long-term solution.

But others involve getting considerably more “precious”: feeding and weedkilling the lawn, and/or mowing everything shorter (basically saying goodbye to the daisies and the other low-growing wildies) and pruning overhanging trees/shrubs to let in more light.

GET IN CONTACT | Do you have a question for Helen Yemm?
GET IN CONTACT | Do you have a question for Helen Yemm?