London (change)
Today 25°C / 16°C
Tomorrow 24°C / 16°C

Watering greenhouse plants


by Adam Pasco

At this time of year we need to be particularly attentive to plants, especially those in pots, baskets and growing bags. If compost is allowed to dry out plants soon suffer, and then the damage is done.


Adam Pasco installing an automatic watering system in a greenhouseWhat a glorious Sunday in the garden yesterday, and driving my daughter to school at 7.30 this morning the temperature was already 23°C and rising. It probably didn't fall much below that all night, and though a bit restless for me the greenhouse crops are loving it.

Despite opening-up every vent in the greenhouse early, jamming the double doors wide open and damping down the floor with a hose, the temperature inside had already 31°C by 10am.

At this time of year we need to be particularly attentive to plants, especially those in pots, baskets and growing bags. If compost is allowed to dry out plants soon suffer, and then the damage is done.

Working gardeners away from home all day need to adopt growing plans that take the strain out of watering plants. To start with, try and rationalise the number of plants growing in pots and baskets, and if you do always use the largest pots you can. Small pots hold less compost, and less moisture, so bigger is always better. Terracotta pots can be lined with plastic, using old compost bags to reduce moisture loss through the sides of the pots, and moisture retaining gel mixed into the compost at planting time to provide addition storage reserves.

My greenhouse more or less looks after itself. Tomatoes and cucumbers are growing in pots supplied with regular water from automatic watering systems. These are fed from tanks topped up once a week at the most with a solution containing nutrients.

Self-watering capillary matting trays cover the staging, lined with pots of chillies, aubergines, peppers, begonias and more. These deep trays hold a large reservoir of water – easily enough for a week or more. So, other than opening the greenhouse each morning before work and closing vents at night, I don’t need to lift a finger. Automatic watering systems take the strain, leaving the busy gardener with time to tie in leading stems, pinch out side shoots and check for pests, and not lug endless watering cans into the greenhouse.

I haven't checked the weather forecast to see what's in store for later in the week, but with Wimbledon in full swing surely we can expect rain!

But if rain doesn't arrive it really is done to the gardener to make up for the shortfall. A friend of mine took on an allotment this year, but the site has no water at all! That really is a challenge. So, how do you cope when the heat is on?



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Gardeners' World Web User 27/06/2011 at 12:10

Windows, the door and the roof vent are open in my conservatory as well as the connecting double doors to the lounge. The plants of salvias, cosmos and nicotiana which I've grown from seed for the front garden display are in pots lined up in plastic trays which I keep moist. They are certainly drinking up the water now. I have put my large garden umbrella over some of my pots outside to shade them a bit, and all my succulents are in the shade under a huge Bramley apple tree. It does make a change to have to protect the plants from sun-scorch and drought!

Gardeners' World Web User 27/06/2011 at 15:45

Living in the south of Ireland I dont seem to have to worry about high temperatures and if anything, could do with a little more sun and warmth. My cherry tomatoes and strawberries are crying out for it. Any chance of sending some of your weather here? :)

Gardeners' World Web User 27/06/2011 at 21:25

Don't think I've much control of the weather, I'm afraid. Just home from a busy day and even at 10.30pm it's still nearly 24˚C in the greenhouse ... but for how much longer?

Gardeners' World Web User 28/06/2011 at 08:12

Each evening for three days the rain god watered my garden, plus all my pots, wish I knew about lining terracotta pots!!

Gardeners' World Web User 28/06/2011 at 09:51

Lazygardner: please send your rain God to Cambridgeshire! Other areas appear to get a good drink, but not my garden!

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