8 Aug 2018

Timely tips for a heatwave garden



This summer has not been without its challenges for gardeners but I confess I'm enjoying the novelty of having a proper English summer, it's so nice to sit outdoors in the shade.  Daily watering of balcony plants in pots (tomatoes, chillies, salad leaves) has become a nightly ritual but I have to admit that watering pots downstairs in the garden is a hit and miss affair depending on the time available. But I have a few tricks up my sleeve for holding moisture in the garden for longer.

But I don't always get it right. Just today, before heading out for a lunch meeting, I noticed a pot grown Hebe looking more than a bit thirsty. I chucked a can of water over it and hoped for the best. On the train I read this amazing tip:

Pots that have dried out need to be rehydrated slowly rather than deluged with water. (Plants need air as well as water and light.) Ice cubes allowed to melt on the surface of the compost are perfect for this as the compost absorbs the water while they melt. This tip is particularly useful for hanging baskets. Well! I never knew that before. So clever.

I would love to have a seep hose to keep plants watered but that, for me, is out of the question. An alternative is to plant a bottomless plastic bottle next to thirsty plants to direct water to the roots. Plants such as tomatoes, courgettes, squashes and pumpkins will thank you for it!  Bottles with sports caps left on and open before planting will leach water more slowly into the soil. I used to do this but, being mostly plastic free these days, I’d forgotten about it. Time to raid the community recycling bin!

Whatever you do, don't water in the middle of the day unless your plants are seriously wilting. Heat will cause the water to evaporate before it reaches the roots of the plant and you'll only encourage roots to grow towards the surface.  Much better is to water the soil (not the plant!) in early morning or, best, after sundown when the plant can soak it up and rehydrate it's cells.

Mulch around your plants with pebbles, bark chippings or a thick layer of compost over damp soil; the mulch layer will help to retain moisture.  At the Garden Press Event in February, I noticed that a retailer of garden planters used clay pebbles both in the soil and on top.  They're more usually associated with hydroponic growing but, used with soil, they'll improve drainage and aeration; used as a mulch, the pebbles hold water and help to reduce water evaporation. I've mulched my hanging basket tomatoes with them.

Wind at any time of year is damaging to plants but in hot weather doubly so. We had some strong winds recently and my first thought was to move my plants into the shelter of my balcony floor. A stiff breeze will wick moisture away from the leaves, leaving them vulnerable to scorching. The plant will try to replace moisture by moving water up the stem from the roots (transpiration) but if the soil is dry, your plant will quickly, and possibly permanently, dehydrate.  The solution? Up the watering in windy weather, stake your plants so they don't topple and, if possible, move pots into shelter away from strong wind.

Right plant, right place.
Know your plants.  I might have to eat my words later but there's a real possibility that heatwave summers might become a regular thing so it might be prudent to rethink what to grow in the garden.  Annual plants (most veg) don't have time to establish deep root systems so should go to the top of the list for watering in a heatwave. Tender plants can be protected from the heat with horticultural fleece which will create a bit of shade. Perennials, on the other hand, are a bit tougher.  My neighbour waters his perennial cabbage leaves deeply once a week, even in this heat.  Cardoons and artichokes, once established, are also okay in the heat as are the South American Achocha peppers that seem to have self-seeded across the veg patch and are growing steadily on practically no water. Sweet corn also likes a bit of heat and can get really tall in a hot summer. And, of course, don't forget herbs - sage, thyme, oregano - all the Mediterranean herbs! - are loving this heatwave, as are the bees flocking to their flowers.

And speaking of flowers, any plants with silvery leaves will be fine - this has been a really good year for lavender, perovskia (Russian sage), Limonium latifolium (sea lavender), Lynchis, Stachys byzantina (bunny's ears) and grasses. Agapanthus, Eucomis, Salvia and sedums all love the sun and, being perennial, just pop up and do their thing with minimum human interference.  Although I'd hate a summer without sweet peas and sunflowers, wouldn't you?


11 comments:

  1. Along with all the good advice you've solved a puzzle on my allotment. One part has lots of little clay ball; and the old compost I took out of the greenhouse had them in too. I wasn't sure if they were some kind of slow release feed or slug killer. Either way I've been a bit suspicious of them. Now I have the answer! They are useful after all.
    Also, I hadn't thought of putting bottles with their cut off sides down as a slow watering system. I've got them the other way up so I can fast water the tomatoes in grow bags.

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    1. It's always a good idea to be deeply suspicious of anything left behind on an allotment - especially given the chemicals that were so popular until recently! Typically, as soon as I posted this, it started raining here, lol! With water bottle watering, it's the spout end that goes in the soil and you chop the bottom off to pour water into the well. I think that's what you're doing already with your tomatoes, Lucy. Glad the tips were useful; sunshine is lovely but all that watering can get a bit overwhelming!

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  2. Great advice Caro and have done the bottle gizmo recently on pumpkins. However inspite of lots of flowers there are no signs of fruit. Nothing to do with the watering method all to do with lack of cross fertilisation. Boo hoo.

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    1. Hi Sue, I had the same thing last summer at the allotment - lots of flowers but no fruit to be seen on the pumpkins. Don't despair, I was really surprised at the end of October to find several squashes and pumpkins where I thought there was none! It might be worth giving the flowers a helping hand if you think fertilisation is to blame. It's a bit windy for bees at the moment!

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  3. We have lost a few things in the garden as we have been concentrating on keeping edibles alive. We have had to water in the afternoon but have used cabs without a rose to water at ground level and it seems to be working OK.

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    1. Hi Sue, I think that way of watering is more effective than using a hose where lots of the water goes onto the leaves. Pity it's so time consuming though! A friend waters with cans and considers it his green gym exercise as there's a long walk to and from the nearest tap.

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  4. Those are some early good tips. I wondered why one of my pots was still looking unhappy despite me giving it lots of water - now I know why! Sarah x

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    1. Hi Sarah - if your pot plants don't recover after a good watering and feed, check the soil for vine weevils. They're those little white grubs with an orange 'eye' that feed on the roots of plants - a plant killer for sure! You can sort those out with nematodes if the plant is a special one worth keeping. Hope this helps! xx

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  5. Good post. My plot has suffered from the dry, hot weather and the wind. Even so some plants have done better than expected. I've well watered early(ish) morning all round weekly and between times where needed. xx

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  6. Some excellent tips Caro :) I know that I'm guilty of deluging desiccated plants rather than giving them more gentle liquid relief. I will try the ice cubes technique next time. I sink bottomless old yoghurt pots into the earth round the base of all my sweet pea and bean plants in an effort to direct the water to the roots when watering. Could not do without my sweet peas :) We have have some decent rain today which was most welcome.

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  7. All tips most welcome!!! I did like the ice cube one!!!xxx

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