Predicting Frosts At Home
Hello friends,
This week I thought I'd share with you how I predict frosts at home using weather resources for New Zealand which are available on the internet.
More often that not, thanks to us being in an inland valley, the weather forecast for Dunedin doesn't apply to Mosgiel, and yet the Mosgiel regional forecast is meant for areas further inland than us. Over the years I've used a bunch of different weather forecasts and also my gut feeling to know when to put frost cloths on my citrus and other frost sensitive plants.
The usual frost set up for us goes something like this: In autumn, winter, and spring, a southerly front/storm comes in from the south west from out over the southern Pacific Ocean. It brings with it either rain/snow, wind, and cold temperatures. After the southerly blows through, the wind dies down, and the sky clears, usually mid afternoon/early evening, then it cools overnight and then we get a frost (or a number of frosts) in the days following. Our frosts can get down to around -6˚C in the middle of winter, but in autumn and spring they can hover just around 0˚C.
Because this set up is pretty predictable, I've come to get a gut feeling about frosts in our local inland valley. So in the late afternoon after a southerly storm when I tend to get a feeling that it'll freeze, that's when I turn to my top three weather forecasting methods.
First up I go to Metservice's website:
On the today forecast in the Dunedin Regional Forecast the -4˚C predicted isn't for "today" but rather than the next morning, on Monday. It's all a bit confusing but it's the best way that it works for me, and the temperature is approximately right. I then look at the "Monday" forecast to see if it says calm winds and frost. In autumn and spring, this forecast tends to be incorrect in predicting frosts.
The second forecast I check is Weather Watch's frost risk forecast. The blue and purple sections on the map show the medium and high risks areas for frosts for the coming days. You can also look at their minimum temperature map to see the temperature bands.
From my observations, Weather Watch's frost predictions are the most accurate. Basically if frost risk map shows blue (or just on the edge of blue), we will get a frost. I trust this frost predictor rather then the other two that I use.
And finally the last frost predictor I use is Rural Weather's forecasts. Just go to rural weather, enter which area of the country you are in, and it'll show you rain, wind, temperatures, fog/cloud, and frost predictions for the coming days.
Their frost trend graph is still in beta, but it is good for predicting frosts. The dark red sections means most likely to have a frost, and the pink is a slight risk of frost. It also shows you what times the frosts might occur. This is my second favorite frost forecast.
With all three of these forecasts in mind, and with my gut feeling telling me there will be a frost, it's time to pull out my frost cloth. My citrus plants and my wasabi plant are sprayed with liquid frost cloth, which protects them down to around -3˚C (depending on how much rain there has been recently). And I also put frost cloth on top of them as double protection, because sometimes, if the plant is still actively growing, the tips of the leaves and flowers may not have been sprayed by the liquid frost cloth. This method works down to around -6˚C, which is usually the coldest frosts we get. If the frost is predicted to be lower than -5˚C, then I just chuck more and more frost cloth on the plants until they are cocooned.
In this case, we did indeed get a frost, which got down to -2.4˚C, which is warmer than the predicted -4˚C by Metservice, but colder than the predicted temperature for Dunedin. It was well and truly worth spending the time putting the frost cloth on my beloved citrus and wasabi plants overnight.
And so, as you can see that my frost prediction method for home is a good setup, and it works for me most of the time. It's much more tricky to predict frosts in late spring though, and we are now getting frosts up until the first week of November, which is a huge risk for my newly emerged dahlia plants. And considering that I have over 50 dahlia plants in my garden, I do not have enough frost cloth and buckets to protect all my plants that late in spring. And that's when I raid the linen cupboard, and use all my spare sheets and blankets as frost protection. As climate change continues to evolve in the coming years, I think our late spring frosts will only get worse.
Have a wonderful day
Julie-Ann
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How To Keep My Outdoor Dahlias Alive During Spring Frosts
Hello friends,
We're at the time of the year when the days are getting longer and warmer, and my dahlias in the ground are starting to wake up and poke their heads above ground. This is a good thing, but it is also very stressful because spring weather in Dunedin can be quite fickle.
It used to be that you could plant temperature sensitive crops of all types in Dunedin at Labour weekend, which is in the third weekend of October. But for the last three years we either have had a snowfall in the last week of October, or we have a very late frost in the first week of November. As this is a death sentence for any dahlia growing in the garden, I've had to come up with a frost protection method which will work for all my dahlia plants.
Over the last couple of years I've tried frost clothing my dahlias, but this method is prone to the wind blowing the frost cloth off overnight before the frost at dawn. So I've had to resort to a more brute force method of protecting my dahlias. After many trials, I finally settled on using a lot of small, cheap buckets, placing them on top of the dahlias on risky nights, and holding them in place with a spare piece of firewood.
It's not a very pretty method, but it does the trick. It does take a lot of work though, going around each night putting buckets on dahlias, and then the next morning removing them when the temperature rises. Larger buckets are needed to protect the dahlias as they get bigger. Then there is the problem of running out of buckets if too many dahlias are above ground, and I'm not proud to admit this, but that's when I resort to raiding the kitchen cupboards for ice cream containers and mixing bowls...
I used to go around with a wheel barrow collecting up all the buckets and firewood each day, and then redepositing them each night, but now I've gotten lazy, and leave them sitting beside each dahlia all the time for easier distribution. It may make the garden ugly looking for about a month, but I can totally live with that.
The whole process is a giant pain in the ass, but it's completely worth it in summer when my garden is filled with flowering dahlias.
Have a wonderful day
Julie-Ann
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Making Citrus Frost Cloth Covers
Hello friends,
After buying a frost cloth cover from one of our local garden centres back in May, I wanted to make bigger versions for my three citrus plants before winter arrived.
Luckily I had some very thick frost cloth in storage from last year, so I tracked it down and then got to work. The frost cloth was 2 metres wide and many metres long, so I used the width of the frost cloth as the height for each frost cover. I wrapped the frost cloth length around each citrus plant, added extra space for wiggle room to fit it over the citrus plants, and then marked it out on the frost cloth. I decided that adding a zip was just extra work, and more expensive, so I didn't bother with it.
Once I had measured each plant, I went up to my craft room and cut off a length of frost cloth for each frost cloth cover. I then folded each section of frost cloth width wise, so that the width of the frost cloth formed the sides of the frost cover. The length of frost cloth that was folded in half then formed the top and bottom of the frost cover. With this done, I sowed along the top and the side of the frost cover. The bottom of the frost cover was left open for making the casing for the pull string, and to pull over the citrus plants when the frost cover was finished. I used a normal straight stitch on the sewing machine, and made sure the ends were well tacked down.
The next step was to sew a casing in the bottom of the frost cover, leaving a small opening so I could insert some nylon rope in a circle around the bottom. I purchased some general purpose nylon rope from Mitre 10, and some cord pullers from Spotlight.
After sewing the casing, it was time to unwind the general purpose rope, and insert it into the casing. This was when Rosie cat came to assist me, and she helped me add the rope and the cord pullers to all three citrus frost covers.
After making sure the cord pullers all worked, and tying the ends of the rope tight together, the frost covers were ready. After trying on each frost cover to the corresponding citrus plant, I labelled each one with a permanent marker.
It's now winter, and we've had multiple frosts now. The frost covers have been such an asset to have, as they are so easy to pull on and off. It's really been so much easier to protect my precious citrus plants from frost and snow. And to make the frost covers myself, it was just a crafty bonus.
Have a wonderful day
Julie-Ann
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Outdoor Citrus Frost Cloth Project
Hello friends,
Sometimes it's just easier to buy stuff you need for the garden, and especially when the task you need to complete takes up a lot of time.
We were in the local garden center the other day and spied a new product on the shelves. Egmont is now selling a frost cover with a drawstring and toggle, and the frost cover is zipped on for easy placement and removal. The frost cloth is commercial grade, and the fabric is 30 gsm. I didn't buy one at the time because the bag is only 80 cm wide by 100 cm tall. The bag wouldn't be big enough to fit any of my citrus plants.
But after thinking about it over the Easter weekend, the bag would be big enough to use as a template to make larger versions that would fit my citrus plants. I went out and bought one after Easter, and it was only $10, which is a pretty good deal considering how big the zip is.
As you can see from the photos the frost cover bag is a rectangle which has been folded in two halves with a zip down the middle. The top is sewn across with a heavy seam which won't rip easily. The bottom contains a fabric casing to hold a thick cord, which is held in place by a strong toggle.
I tried placing the frost cover over the smallest citrus plant I have, which is our mandarin bush, and as you can see it is pretty squished inside the frost cover. It definitely needs more space so that the branches don't get squished. But the frost cover was pretty easy to put on, and the thick cord and the toggle did a great job of keeping the frost cover in place.
So even though I can't use this frost cover to protect my citrus plants, I can use it as a template to make bigger versions that I can use. And afterward I can use this frost cover for my small Camellia sinensis tea plant over winter, so that is a good bonus for me. In the coming weeks I'll make up the template for the citrus plants, and build a trial one for testing.
I did ask the garden center if Egmont planned on making bigger versions, but she said that this product had only just come onto market, so not likely this year. They were going to pass on my suggestion for Egmont make bigger versions in the future.
My suggestion is if you do have smaller citrus plants, that the Egmont frost cover is definitely worth buying for your plants over the coming cold season. With it being easy to take on and off, it'll save you time and protect your precious plants from any frosts that do happen.
I just need to now pull out all my current frost cloth stash and see if I have any frost cloth that can be used for making some bigger covers for my own plants.
Have a wonderful day
Julie-Ann
Want to discuss my post? Feel free to chat with me on Instagram or Mastodon or Bluesky.
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