Chill Out!

Chill Out!
How many times have you heard that expression in your life?!
It was coined about 1980 or so and means to relax, calm down or go easy. The dictionary doesn't give the meaning of the phrase the way I am using it today. I am going to tie it into horticulture.
Chill, relates to cold. In the world of plants, cold can be a death nail. To some plants and trees however, it is essential for propagation and the future. I am, of course, referring to Chill Hours or Chill Units. These are an approximation of how many hours of weather between 32 degrees and 45 degrees a plant requires to properly go dormant so it can wake up and blossom and/or set fruit. If you really want to get fancy and be ready for an appearance on Jeopardy, this is called vernalization (which comes from the Latin vernus, meaning Spring). As a side note, surprisingly, there is no additional benefit from lower than 32 degree temperatures.
Deciduous fruit trees, bulbs and some other plants that go dormant during the Winter need a minimum number of these hours. However, the problem is, it is very difficult to measure chilling hours precisely. If you are looking at a catalog of fruit trees, the listed chilling requirements are, as I said above, approximations or estimates. Of course, every location has a different amount of Chill Hours. Here in Charleston, SC our average is 400-600 hours. Central Florida receives between 100 and 300 hours. Up in New Jersey they have about 800-1000 chill hours per year. So what does this all mean to the average home fruit grower? PLENTY!

Let's use Apples as an example. They have a pretty wide range of chill hours, (200-1,800) but many of them need about 800 hours. I should also add here, nursery catalogs often will contradict each other. One may say that a certain tree needs 700 hours and another says the same plant needs 900 hours. In such cases, it is better to use the higher number to reduce the potential of not meeting chill requirements. So, using the information above, let's say I wanted to grow Winesap Apples. They have a Chilling Hours requirement of 800-900 hours. In New Jersey, they would do great. Here in Charleston and down in Florida, not so much.  Why you ask?
If the flower buds do not receive sufficient chilling temperatures during Winter to completely release dormancy, trees may develop problems such as delayed bloom, delayed leafing out, reduced fruit set, or no fruit set and reduced fruit quality. When I tell people this, they then usually ask: Well, if I plant a low chill apple, say Anna (200-300)in South Carolina won't that work? The best answer I can give them is "maybe". Remember I said this is all averages. If a tree only needs 300 hours and it is growing in a 400-600 hour area, what happens when the 300 hours are reached and there is a warm spell. The tree breaks dormancy thinking it is Spring and begins to flower. Then old man Winter returns with a icy cold snap, killing the flower buds...result, no fruit. Now, if it stays relatively warm, the tree will be fine and you will get fruit. As a general rule of thumb, when looking at a range of chill hours, stay within about 100 hours either side of your area.
Confused yet?
The sad part is, this kind of information is rarely printed on plant tags, so home gardeners are left in the dark about the proper fruit tree selection. This information also goes for Plums, Cherries, Peaches, Apricots and many other fruit trees and plants.
I am not going to knock any of the big box stores, but before you buy any of their "great" Spring fruiting trees, make sure that you do some research and see if it will do okay where you are. I have a story, somewhat related, about Blueberries. There was a store in Charleston selling Northern Highbush Blueberries. As you might guess, NORTHern Highbush will not do well here in the SOUTH!
This type of thing is, hopefully, where my blog and I can help. If you are unsure of something, please feel free to ask. My e-mail is TheCitrusGuy@netzero.com
I hope I have cleared this often confusing topic up a little. If you have any questions at all, please use the e-mail address above. When it comes to growing fruit, one of the biggest things you need to remember is...Just Chill Out!
Happy Growing!
Darren

Plant Cold Protection

I posted last week about bringing your houseplants in for the Winter. Hopefully you all did. What about the plants that are just way to big to move or are in the ground? Again, I am lucky in the aspect that I have a greenhouse and a fairly decent, healthy back, so I can move my 30 gallon pots. What if you don't have either of the above and want to protect that plant that is marginal in your neck of the woods?
Lets see if I can give you a few ideas.
Although I live in the Southern part of the United States, Winter sometimes brings cold temperatures that can cause severe damage to many of our landscape plants. Early frosts in the Fall can cause damage on plants that are normally adapted to our area. Plants need adequate time to harden off (adjust to outdoor conditions) before freezing temperatures occur. A plant’s ability to withstand cold temperatures will depend on the plant species, but also on how low and how fast temperatures decrease. When temperatures gradually decrease, a plant can acclimate, or adjust itself, to withstand colder temperatures better. Sudden decreases in temperature cause more damage in Fall or early Winter than similar low temperatures well into Winter. New growth that has been stimulated by late Summer pruning or fertilization is very susceptible. Hopefully you weren't outside in the past month or two feeding your plants or giving them a haircut. If you weren't, then you are already ahead of the game.
Ideally, The best way to prevent cold injury to plants is to choose ones that tolerate the cold temperatures in your area. We all know though, that pushing the envelope is sometimes more exciting and offers a wider range of plants.
So, in addition to right plant selection, you want to put the plant in the right place. During the Winter, the coldest spots are often found on the North and Northwest part of the property and in low areas where cold air settles. The warmest spots are usually on the Southern part of the property. Placing plants under non-leaf dropping trees will add some protection, as will using a fence, building, wall or temporary shelter made of plastic. Placing plants near a sidewalk or street can even add a few degrees of protection. These things absorb the heat and give it back off at night. For container grown plants, their roots are more exposed because they are above ground. Push together container plants that are left outside and mulch or cover them to decrease heat loss from the sides of the containers. Wrap the base of the containers in plastic, burlap, or blankets to reduce heat loss. Remember also, that plants that grow close to the ground are usually protected by heat radiating from the soil. Plants that are tall and more open do not receive this radiating heat and are not protected from the cold.
Covering your plants helps protect them from frost as well as from extremely cold temperatures. Covers that reach the ground and do not come in contact with foliage form a layer of insulation from the cold temperature. To prevent foliage breakage, avoid having the covers (sheets, blankets, painters drop cloth, etc) touch the foliage. This can be accomplished by using tomato cages for smaller plants and lumber teepees for larger ones. Don't forget to weigh down the sides so a gust of wind will not blow it off. When extremely cold temperatures are predicted, place a light bulb (60 watts or higher) or other heat source (spotlight) under the cover to provide heat. You can also use some of the old Christmas lights that we all had as children, you know, the ones that would melt your toy if it came in contact with? Check the lights before relying on them, the newer ones do not produce any heat. Be very careful when using a bulb or other heat source, which can be a potential fire hazard. Do not let the bulb or heat source come in contact with the plant (Christmas lights being a kind of exception) or the cover. Remove the cover and provide ventilation during the day, the sun can very easily burn the plant or at the very least, the extra warmth could possibly cause the plant to break dormancy. This precaution is critical when using plastic covers.
Watering plants before a freeze can help protect them from cold injury. Soil that is well watered absorbs more heat and gives it back to the plants at night. I don't have this problem here, but, Cold weather can also cause the ground to freeze. When this occurs, water is unavailable to roots; plants continue to transpire (lose water from their leaves) and dry out. Watering the soil to thaw the ground makes water available to roots.
Mulch will act as an insulator, so it too can protect plants, especially from wide swings in temperature. Sometimes the cold temperature is not what damages the plant, it's the freeze/thaw cycle affecting the soil and causing it to "heave" the plant. The roots basically get thrown out of the soil and break contact with it. Something to keep in mind about mulch, this "insulation" works both ways. It can prevent the soil from drastic swings,and getting too cold, but it can also prevent it from warming up when the time comes. You may wish to rake it back away from the plants as it starts to warm up in Spring.
Now occasionally, Mother Nature actually provides the best blanket of protection in the form of a light snow. Up to two or three inches of snow not only insulates the ground around your plants, but it also provides a blanket of protection over the leaves. If you have a situation in your area (I don't, usually) that this could happen, you need to think way in advance.

This is a picture of some Wax Myrtles, before the wet, heavy snow, hit us in February of this year. They were about 10 feet tall prior. If the homeowner knew this was coming, if ANY of us had known this was coming, they would have been pruned back in the middle of the Summer. This event caused considerable damage. Of the limbs that broke, some were as big as six inches in diameter. This picture was taken too late to do anything about it. What should have been done, other than the preemptive pruning? Someone should have gone out there and lightly shaken as much of the snow off as they could. The plants are fine and rebounded, but the shape of them is not one of beauty, Mother Nature is definitely not a landscape designer.  
To sum this all up, healthy plants are more resistant to cold injury than plants that are weakened by disease, by insect damage, or by improper care. Plants that are being grown in their proper growing zone will do better than one that is 3 zones off. With an ounce of prevention, and a little work, you too will produce a plant that can wear a tag that states "I survived the Winter of 2010/2011".
Happy Growing!
Darren

Man, That's Cold

I received an e-mail from a new friend of mine named Claudia. She also writes a good Blog, Gardening Naturally with Claudia. You can check her blog out at:
http://gardeningnaturallywithclaudia.blogspot.com
She asked me a question that I never really gave much thought to, So I figured it would be a good subject for today's posting. She lives in Zone 5b (-10 to -15 Fahrenheit) Man, That's Cold!! She wanted to know what Citrus would be hardy in her climate. There is not much, BUT, there are some!
With that being said, let me give a few insights. Factors affecting hardiness are of course, minimum temperatures, how long it is, weather before the freeze, soil moisture and wind protection.
I have touched on some of this in other postings, but will revisit them here. Minimum temperature goes without saying, -10 to -15 is pretty cold.


As you can see from the above map, that kind of temperature and colder covers about one fourth of the country. So most of the ones I will list can be grown even further South.
How long the freeze is: One night of freeze may not hurt a plant too much, a week (or longer) could be another story.
The weather before the event: If you have had very cool temperatures and it has been rather consistent, that is a lot better than warm for a few days then a wicked cold spell.
Soil Moisture: Make sure plants are well watered before the event, the wind also falls under here. Cold and wind dry plants out. A dry plant is much more apt to be hurt by a freeze than a well watered one.

Now, as for Citrus that can handle that kind of cold. There is really only one for a Zone 5b. Poncirus trifoliata. It is hardy to about -15F There are two cultivars, a straight one with straight thorns and branches and ones with curved branches and thorns called 'Flying Dragon'.
This is one of the few actual deciduous (loses it leaves) Citrus. The best way to describe the fruit from this tree? I got this from the book 'Hardy Citrus for the Southeast' By Tom McClendon. He writes, "The fruit are edible, meaning that you won't die from eating them". That pretty much is the best description I can come up with other than, if you don't mind the taste of kerosene, this fruit is great! Tom also has uses listed for the Trifoliates: Hybridization, Ornamental and TARGET PRACTICE.
If you are willing to provide a little protection, maybe plant on the South side of your house and very close to a building or wall, you could grow some of these: Hardy to about 5F.
Citrandin (Poncirus X Citrus reticulata)
Citrange (Poncirus X Citrus sinensis)
Citrumelo ( Poncirus X Citrus paradisi)
Nansho Daidai Sour Orange (Citrus taiwanica)
Some of these may be palatable to you. I have actually had a decent Nansho Daidai. I also enjoy Sour Gummy Worms, so take that into consideration.

If you can protect down to about 10 degrees the list gets much better:
Bloomsweet Grapefruit
Yuzu (as seen on Martha Stewart)
Yuzu Hybrids
Nippon Orangequat
Changsha Mandarin
Juanita Tangerine
And actually there are many others.

Down to about 15 degrees and you are getting into the:
Kumquats and their Hybrids (Sunquat, Procimequat, etc.)
Calamandarin
Sour Oranges

Your Satsumas are in the upper teens, I don't recommend pushing these there though. I try to keep them no lower than mid to upper 20's along with:
Sweet Oranges
Meyer Lemon
Grapefruits

Like I said in the beginning, there are a LOT of factors that will effect cold hardiness. There are other steps that you can take to protect them.
Build a mini greenhouse over them. Grow them in Containers. I actually could go on for hours talking about this subject alone. Hopefully this gives you some ideas to try. Finding many of these varieties may prove to be difficult. There are some websites that you might be able to find some of them. Pick a couple and do a Google search. Later, I will do a post on finding some Citrus online, I have some great friends and will give you their websites. That my friends will be for later, for now you have to wait and come back often! LOL
Happy Growing!
Darren