Thursday 25 April 2013

How to handle Spring weather

Here in the UK complaining about the weather is a national pastime. It was only a week or two ago that we seemed to be stuck in the grip of a seemingly interminable severe Winter. Now we have typically "April" weather - sunshine interspersed with heavy showers of rain during the day, and cold nights still - occasionally frosty. On the TV Weather Forecast we keep being reminded that the sun in April is as strong as it is in August, and to go easy on the sun-bathing! I'm not ready for sun-bathing just yet, but I have been thinking very carefully about the effects of the weather on my plants.

Little plants, like my tomato seedlings, need lots of light to prevent them going leggy. This year I have had the benefit of the new Grow Light House, so my tomatoes are looking good, but I want to give them as much natural light as possible and to accustom them gradually to life outdoors. In the mornings, after the sun has come up and the temperature has reached about 10C, they go outside into one of my plastic mini-greenhouses, where they stay until about 6 p.m. when they come in for the evening and spend the last hour or so of daylight on a bedroom windowsill.

Notice how I have weighed down the greenhouse with some bricks. These structures have a lot of wind-resistance and are prone to taking off if not secured!

The process of gradually acclimatising the seedlings to outdoor conditions is known as "hardening off". Seedlings planted outside without the benefit of this procedure are likely to die of shock - or at least to do badly. If you are buying tomato seedlings, look for short sturdy ones, with stems that are purple-coloured rather than pale green. Dark colouring of the stems is a sure sign that they have been properly hardened-off.

During the Winter I protected some of my potted herbs in a coldframe, and now I am using the same structure to protect a couple of pots of shallots as well. In order to help the plants inside it to acclimatise, it is advisable to open the lid of the frame for a few hours whenever you get a sunny day.

If you don't open the lid, the temperature inside can get very high if the coldframe is in direct sunlight. Of course you have to remember to close it later in the day too. At this time of year you really need to adopt a "Start of Day" procedure and an "End of Day" procedure to make sure that all your plants get the right treatment! When I'm at home during the day I often have a "Middle of the Day" procedure too, whereby I transfer trays of seedlings from windowsills on one side of the house to another, in order to maximise their opportunities for getting natural light.

My long cloches have also seen a lot of use recently. They are good for providing weather-protection to young seedlings or newly-sown seeds, but again you have to think about what may happen if the temperature inside them gets too high. Until last weekend I had two of these cloches protecting my Shallots, but I raised them up on their legs, so that some air could get underneath. I would like to have removed them completely a few days ago, but I was pretty sure the foxes would dig up the Shallots if I did.

 Since this photo was taken, the cloches have been replaced by nets.

If the picture looks a bit fuzzy, it's because the nearest bed (where the cloches were) is covered in fine extruded-plastic netting, which looks almost grey in the strong light conditions. It's a very difficult type of net to handle (I don't think I'll buy any more like it), but hopefully it will keep the foxes away from my Shallots.


  1. I am at the stage of checking the daily forecast before I leave for work. On most days I have the large greenhouse door open & the side vents open. I would hate to lose a greenhouse full of seedlings at this stage.

  2. I weigh my plastic greenhouse down with a bag of compost, the wind can whip them away with one gust otherwise.

  3. Excellent advice, Mark, about raising cloches to let the air in and to have a system of monitoring the welfare of your plants at both ends of the day. It certainly seems to have paid off with your tomato plants! I had to smile at your moving seedlings around indoors during the day - I find myself doing the same as my flat is east/west facing!

  4. The problem with cloches on the plot is that we wouldn't be there often enough to make sure they didn't get too dry or too hot. That is assuming no-one took a fancy to them!

  5. Hi Mark, great tip on checking the stems of any tomato starts that are purchased. I hope your weather continues to be more 'typical' April weather. We've had a fine week of sunshine with temps in the high 70's F. Really quite warm for our area this time of year, but I'm not going to complain! I've made lot's of progress with digging out these old perennial beds I've inherited. Cheers, Jenni. P.S. How do these foxes get into your back yard? It appears you are completely fenced off?

  6. Good ideas and tips Mark, we may moan about weather conditions that don't suit us but whatever the conditions, vigilance is always a good policy in the garden.

  7. At one point I tried using plastic hoops but I just can't be relied on to remove them when it gets hot out. So I stick with row covers. Not as good protection, but much safer for the forgetful gardener.

  8. Your post reminds me of just how much effort us gardeners take to protect their plants. I would really like some cloches; I must check out prices.


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