Wednesday, May 14, 2014

How to protect your herbs against frost

The husband and I love growing our own herbs and veggies, and use ingredients from our garden all the time. At the moment we are growing rocket, parsley, sage, rosemary, tomatoes, chillies, spinach, leeks and peas. Some from seeds we harvested from previous crops and others from seedlings we bought.

Our little herb garden.

Livingseeds sells the most fantastic heirloom and specialized seeds for veggies and herbs. They also send out very informative newsletters concerning gardening, and I found this one about frost very appropriate for the time of year we are heading into:

One of the most common pieces of frost advice is that if you water the plants down in the morning, then they will not get damaged by frost. This is only partially true and only in certain circumstances.

Frost is not the issue, it's a symptom of the problem. The problem that we as gardeners face is the freezing of our plants. This freezing causes the cells in the plant's leaves and stems to expand and rupture. THAT is what causes the damage. If you spray the plants before the frost forms then you are affording some protection. However, if the plants are already frozen, the damage has already been done and spraying them is a waste of time.
Watering the plants has the effect of raising the ambient temperature around the plants to that of the 'unfrozen' water. It may sound strange, but when water freezes it releases heat that warms the plants.

Watering to prevent frost damage is best done early in the morning, just before sunrise and it will only work IF the plants are not already frozen. Once the plant cell has been frozen, it would have ruptured already.
Pouring water over a frozen plant is not going to fix the issue any more than pouring water over a cut on your finger would heal the wound.

Living in frost country, we have to learn to accept and deal with these losses every year. One of the ways to get the most from your frost sensitive plants is to lift them the evening before a 'killing' frost and hang them roots and all upside down in a protected spot. How do you know when you are going to have a 'killing' frost?
There are a few thing to look at.

1) A very cold afternoon wind.
2) Still nights
3) Clear sky's
These are the most common 'signs' that one would look for as frost indicators.

Slowing down the damage is your next option. This can be done in a number of ways.
1) Frost guard and hessian sheeting are two of the most common ways of protecting plants. This can be put over the plants and removed on good days for the plants to benefit from the winter sun's warmth. The best time to put the cover back on is early-mid afternoon to allow the trapping of some heat before sunset.

2) Make a 'mini tunnel' with some plastic sheeting and heavy gauge wire. Use the wire to bend hoops to support the plastic and bury the ends of the plastic in some soil. This can raise the temperature by a good 2 deg.

3) Watering your plants before sunset, and preferably quite early in the day will help to reduce frost damage. Wet soil holds more heat than dry soil and it will typically raise the temperature above the soil by 1-1.5 Deg C.

4) Lastly, you can prevent frost damage by either transplanting sensitive plants into pots and keeping them indoors over winter, or you can go the whole hog and get a climate controlled hothouse to keep your plants in. We transplant a few plants that we are pampering specifically for seed, otherwise we take what winter throws at us with joy.

If you live in frost country, frost will eventually take your summer veggies, say goodbye with pleasure because the seasons are here for a reason.

Finally, it's important to take note of your first (and last) frost date. It's good to start building a record of when you get your first frost every year, as this will help you to plan your gardening.

Visit their website: for loads of info on gardening and to shop for amazing heirloom seeds. 

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