Wisteria hysteria as late frost causes panic in the garden

Wisteria hysteria late frost Green Fingered Blog
It's been a nervous week for gardeners in the southern half of the UK. Weather forecasters predicted unseasonably frosty mornings as a blast of cold air spread across the country from the Arctic. Although late April can often be rather chilly here and can slow plants' development considerably, it is rare to get a seriously cold spell with the potential to cause significant damage.

There is nothing in my garden which isn't hardy to at least -5C, so a bit of frost is unlikely to kill anything, but it can still ruin my day! It's all about timing. 

I have a Cercis siliquastrum (Judas Tree) which provides a dazzling display of pink/purple flowers on almost bare stems. I have trained a Wisteria sinensis over an archway across the main path along one boundary. 

You will have your own favourites that come into flower at this time of year but to my mind Wisteria and Cercis are amongst the most glamourous plants in the garden. 

Wisteria is a magical plant, it's long racemes of scented flowers arching downwards from scantily leafed stems in May are a joy. 

Cercis is less commonly seen, and has a sense of the Mediterranean about it, giving it an air of superiority. They are both definite star attractions when in full bloom. But more mundane plants can suffer from the late frost too. I'm growing potatoes in bags which have recently poked their first leaves into the open air. 

Cercis siliquastrum (Judas Tree) in flower Green Fingered Blog
Cercis siliquastrum
The view of a Cercis or Wisteria in full bloom is a real treat, and the scent of the Wisteria delightful. 

They both take a very long time to open their flowers, and there is a period of several weeks during which they can be seen steadily producing more and more buds, promising a fantastic display but making us wait for what seems ages for the sunshine and warmer temperatures before they will open and allow us to see the whole show. 

This creates considerable anticipation, knowing what is to come, being able to sense from the number of buds how good it will be, but having to wait. And hope there is no late cold snap.

Wisteria sinensis buds in early spring Green Fingered Blog
Wisteria buds in late March

It has happened before. Wisteria has a reputation of being difficult to bring into flower, with a potentially confusing pruning regime required to get the best out of it. 

So having planted one for the first time, got it established, and then pruned it, to recognise the first few flowers forming in April a few years ago was both satisfying and tantalising as I waited for them to open.

But that year there was a late frost and all the flowers became damaged, shrivelled up and fell off, depriving me of what would otherwise have been a highlight of that time of year in the garden, and a rewarding experience.

Cercis flower buds ready to open Green Fingered Blog
Cercis flower buds - ready to go!
This is my justification for the panic which set in last week when, very suddenly, I became aware of the forecast of a frost which might repeat the disappointment of a few years earlier. 

In my garden neither Cercis or Wisteria usually flower until May, but we have had a mild (though wet) winter, and they are far more advanced than in most previous seasons. They both clearly have more flower buds than ever before too. 

I am desperate not to miss out on the big show, so I immediately began pondering whether I could protect either of them, and how.

The potatoes that I mentioned earlier were straightforward. One of the benefits of growing them in bags outside the back door is that they are relatively easy to protect. I wrapped a length of carpet around them, and put some bubble wrap across the top, held in place with clothes pegs.

The Cercis, I reluctantly decided, would have to take its chances. It was not very practicable to wrap a seven foot high tree with spreading branches.

The Wisteria on the other hand was a more tempting challenge. 

As it spreads across the arch where most of the flower spikes appear, I felt it might be possible to secure enough bubble wrap in place around the arch to protect them from the falling temperatures and ensure that when the weather returned to something more akin to spring, they would be ready to provide the explosion of colour and scent I felt I had been promised. 

You can see the result of my panic at the top of this post. It was, frankly, a poor effort. Wrapping an arch securely in bubble wrap above your head whilst trying not to damage the flowers you are actually trying to protect is at least as awkward as you might think it is. 

By morning half of it was flapping in the breeze and I am sure had there been a severe frost my intervention would have made zero difference to the fate of the Wisteria.
Arch covered in wisteria flowers ready to open Green Fingered Blog
Arch covered in wisteria flowers - waiting to open
Fortunately, to date, it has not mattered. Temperatures got close to freezing, and the water in the bird bath formed a bit of ice, but the flowers I have been looking forward to remain in tact and attached to the parent plant (and the potatoes are fine too). 

The panic is over. Hopefully last night's was the final frost, and things will now warm up a bit. When the Wisteria and Cercis decide to reveal their full glory, you will be able to see it if you follow me on twitter (@GreenFingerBlog) or on my Facebook page. 

Did you panic too? Please share your stories via my Facebook page, or using the comments box. I look forward to reading them.


  1. For about eight years I’ve been waiting for my wisteria to flower again. I didn’t realize how important pruning was to these beautiful plants. This year I was so pleased to see many flowers starting to bud out. I had company at the time and there was a frost warning and I asked my company to help me cover the wisteria. He discouraged covering it, as he thought it would just blow off anyway. So I didn’t. Every flower is frosted. I’m still very upset about this as I was so excited to see those flowers. Needless to say my company was sorry as I expressed my sadness and disappointment. I am angry at myself for being influenced by someone who is just plain lazy.

  2. That's disappointment, but happens to us all - I'm sure you'll have better luck in future :)

  3. Not so lucky with mine. It was beginning to be stunning....always next year

    1. Sorry to hear that, but look after it and I'm sure you'll be rewarded eventually...


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