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Freezing Temperatures & Frost Protection, Part 2

So, we are one day in to our wintry blast. So far the low has only been 30 degrees, which is not a big deal for most things. We also have a lovely coating of ice, which is breaking tree branches right and left. The forecast for tonight is for 26 degrees.

You can see that there’s ice everywhere, including on our garlic! You can see how the waxy leaves caused the water to run while it was freezing!

So, what do you do about ice on your vegetables? LEAVE IT ALONE! The ice is actually a small measure of protection at this point, and at any rate, you need to let things thaw normally. What about tonight? Do you cover things? It is up to you. Even if we get down to 26, you shouldn’t see much damage on things other than potatoes.

But what about fruit trees?

Iced CrabappleThis crabapple is still budding out, not yet in full bloom. For our fruiting apples and other trees, what should you do? First, no need to remove the ice. Again, it is providing some measure of protection, especially as long as it is still raining or drizzling.

The ice will probably melt this afternoon, as the temperatures get slightly warmer. So should you cover your fruit trees to protect the buds and blossoms?

First, you should look at this chart to determine what the damaging temperature would be for the stage of bloom your tree is in and determine how much damage there is likely to be: Critical Temps for Fruit Trees. If you are only looking at 10% damage or a little more, I wouldn’t bother covering your trees.

If you are looking at a significant amount of damage, you could cover your trees, if you have the means to do so. HOWEVER, they are also forecasting 12 mph wind with gusts up to 20 mph. Most likely, the wind will cause your pockets of warm air to blow away, so covering won’t get you much. I know, I’m a bastion of cheery news today, aren’t I?

Looking at the conditions, I would guess that this wintry blast is going to cause some percentage of damage to our fruit crop this year, but probably not a complete loss. But then, it looks like we’re going to get another chance next week too!


Freezing Temperatures and Frost Protection

After a few days of beautiful spring weather, it looks like we are expecting one more wintry-ish round of weather. I’m seeing predicted lows of 33, 29, and 30 for Tuesday, Wednesday, and Thursday nights respectively. Because it has been a fairly cold (and getting later) spring, there isn’t a whole lot that needs protection. Most of your cool season garden vegetables shouldn’t have any trouble tolerating those temperatures unless they have just been transplanted outside. Most fruit trees (with the possible exception of apricots and some peaches, perhaps) are not in full bloom yet. I suppose they might be with two more days of warm weather.

If you have some blooming plants or vegetables that you want or need to protect from freezing temperatures, here is a great article from The Garden Professors blog about how to do that effectively (and why it works): Protecting Plants from Frost.

A Chance of Frost

Those of you who have read this blog through multiple seasons know that I tend to take a rather laid-back approach to protecting vegetables when the weather turns cold in the fall. My typical attitude is that summer vegetables (peppers, tomatoes, etc) have probably about run their course by the time we get to a frost, and you might as well let them go. On the other hand, vegetables like lettuce, radishes, carrots, cabbage, etc are quite cold tolerant. They don’t need any protection until it is going to get down into the mid-20s overnight.

Since we are looking at an early frost this weekend, what to do? (I think this is actually the first early frost in the 5 years I’ve been here. The “usual” since I’ve been here is a frost in early November and often not a hard freeze until December.) The reality is that if you cover your plants for Saturday night, you will probably be able to keep them going for at least another couple of weeks. The question then becomes, will you really get much more ripening on the tomatoes, peppers, etc in that time? My guess is probably not, because even though we aren’t expecting another frost, the highs are going to be the 60s and 70s, while the lows are going to be mostly in the 40s. That overnight temperature is going to start pulling the soil temps down quickly and really slow down growth and ripening on those summer vegetables.

I’m planning to head to our community garden plot tomorrow and pick off the remaining tomatoes and peppers and then see what the weather does. However, I still have a bunch of basil and lemongrass that I want to preserve. These semi-tropical and tropical plants can sustain some damage even in the 30s. I am not ready to harvest and deal with them yet, so we are planning to cover the herbs to keep them going. Our favorite way to preserve these herbs is to mince them in a food processor and then freeze them in either water or oil in ice cube trays. I’ll try to put up a post about that process when I get to it.

The Master Gardeners also planted a bunch of garlic in the Demo Garden this week, so I’ll try to get a post up about that process sometime next week.


Fall Gardening: Dealing with Late Fall Cold

Part 1, Part 2, Part 3, Part 4

Dealing with Late Fall Cold

While heat is the biggest challenge when planting your fall garden, by the end of fall there is the challenge of cold weather. In an average year, the first light frost will usually occur in mid- to late October, although sometimes the first frost occurs sometime in November. A light frost, where the low temperature dips down to 30-32 degrees will not damage fall vegetables. The cold may even improve the color and flavor of the vegetables. Most fall vegetables will tolerate temperatures down to 28 degrees without significant damage. In fact, allowing exposure to below-freezing temperatures will often allow the plants to better adapt to the cold, increasing their hardiness to later cold weather.

On a cold morning before the temperature is back above freezing, your plants may look wilted and permanently damaged. However, by the time the temperature is back above 32 degrees, they will recover and continue growing. It is important not to harvest these fall vegetables until the temperatures are back above 32 degrees and the plants have naturally recovered from the frost.

When low temperatures dip below the mid-to upper 20s, it will be necessary to protect semi-hardy fall vegetables with a light row cover to minimize damage on those vegetables. Some particularly hardy vegetables, such as spinach and kale, will not need extra protection until the low temperature is near 20 degrees.

It is usually best to remove the row covers during the day to allow the sun to warm the soil more efficiently when we are still getting intermittent frosts. As we get later into the year, leaving the row covers on may help create a mini “greenhouse effect” and prolong your growing season once we are regularly dipping into the 20s overnight.