But that's why the leaves fall off- if the tree cannot extract water from the ground via the roots (as they're frozen in this case), the tree etracts water from the leaves and so they die and fall off. Next the tree dies.
That's what confused me - I didn't realise you had a room that get so cold that it freezes.
Yes, Citrus trees are a bit easier than olives though, as most citrus varieties can handle moderate frost. I've moved my olives indoors some weeks ago but I'm leaving the citrus outside till it starts getting seriously cold. Some people say that the citrus even needs a good night's frost or two to encourage strong blossoming and a generous fruit yield in the following year. The trick is knowing when to stop.
Sorry, didn't make myself clear. With citrus trees the roots have to be nice and warm to supply water to the leaves. My room doesnt freeze, it's my kitchen, so normally nice and warm.
However, when the sun comes up and the roots are cold, then the roots are not able to supply water to the leaves, hence the leaves fall off and slowly the tree dies.
If you have a west facing window then the central heating has a chance to warm the roots up over the course of the day, howerver, if you have an east facing window then the sun hits the leaves nice and early, hence the roots being cold.
Fairly lights warm the roots up so they are nice and warm all day long, feeding water to the leaves, promoting growth and good photosynthesis.
I am not very experienced with Olive trees, had one once and it worked well, but not vastly experiencd..........however, I am guessing that maybe this is fairly standard for trees / plants etc
Okay - understood! Thanks for the explanation. It's all learning today
Sorry, the Mrs'll tell you that gardening is not my thing, so bear with me as I share my thought process.
Trees in winter
1) leaves fall off diciduous trees in winter
2) therefore trees must be able to survive without leaves, albeit growth is severly restricted in winter months
3) source of nutrients/water must be roots
And on the topic of ground freezing
1) the ground rarely freezes deeply (excluding tundra!)
2) roots should go deep enough to be below the freezing layer of soil
And for pots/pot plants
1) roots cannot go that deep
2) soil at higher risk of freezing, as it is exposed around the sides to cold temperatures
Put that all together, it kind of makes sense (to me ) that keeping the roots "frost free" would work.
True, with citrus you must at all costs avoid the roots freezing. However, if the leaves freeze that isn't really a problem as long as it doesn't freeze too deep or too long. This is why it helps to protect the pot by wrapping it, but at the same time you should make sure it can still breathe as waterlogging can cause more damage to citrus than frost.
Also, when wintering citrus it is important to watch for new growth. many varieties grow new shoots in winter and that's okay, although you shouldn't really encourage it. But the shock of moving from outdoors to indoors will sometimes encourage the rootstock to grow new shoots of its own from below the grafting. These are normally recognisable by a slightly different leaf shape and they grow faster than the fruitstock and often have bigger thorns. Prune them back immediately as they are sucking energy from your tree.
Olives are more sensitive in that respect and whereas they can survive light frost they can quickly suffer partial damage and it pays to protect them properly. Cellars are okay but the cellar should have a window as they need some daylight. Many olive trees are also grafted and their rootstocks may behave in a smilar way in terms of sending out new shoots so watch that as well.
My olive tree lives on my balcony winter and summer, and it looses more leaves in summer with the heat than in winter with the cold.. It is in a large pot, and I suspect it needs repotting, but otherwise it is doing quite decently.
True that I have a full south balcony, and that I don't live in a cold area... but it ain't Sicily either!
True
As far as (3) is concerned, water uptake is considerably lower in winter than in summer as the tree's metabolism slows down. With the exception of trees from desert-like places such as date palms and yuccas, most trees grow in places where water is readily availeble. Most of the water trees absorb through their roots is evapoarted through the leaves. This creates a continuous flow of sap inside the tree which the tree uses to transport stuff, so it's a bit like the blood circulation in humans. With the leaves gone, the tree loses the evapoartion surface and so the flow is much slower.
Leaves can fall off for a number of reasons (I'll get to this later), but in any case both Citrus and Olives (as per the discussion) are not deciduous and shouldn't lose their leaves at all. This is bad. They haven't evolved with a dormancy ability.
Going into dormancy, Deciduous trees basically suck all the energy out of the leaves and store it as carbohydrate. The sap is generally a bit thicker (higher sugar content)and resistant to frost.
When daylength and temperatures return, the dormancy breaks and the plant produces new leaves. With new leaves there are new roots (so the old frozen ones don't really matter).
Losing leaves in Evergreen tree's are usually caused by: Disease Low light Poor nutrition Root injury In this case, the northern winter obviously freezes, and the daylength is really short.
I'm pretty convinced now that keeping the soil warm (with the lights, also adding a IR light spectrum) will help if you add a UV light suppliment.
Water use
Just quickly correcting a myth.
Plants don't 'suck water' water as such but rather draw the water in response to internal pressure through loss via the leaves.
(effectively this creates a sucking action on the roots - I know, but the roots can't 'suck' as such).
So for your indoor evergreen plant to stay alive, you need to keep the leaves healthy for photosynthesis.
Plants only draw water when they are photosynthesising so you need the light to make the leaves respond to this. (they shut down at night).
So in conclusion: Keep the soil warm to stop the water freezing Balance the light spectrum (UV & IR) to activate photosynthesis control daylength above the minimum winter length All these things to work together to work. If one fails, they all fail.
(one last hot tip going into the spring, is to watch the new growth points. Where die back occurs, this is a classic indicator of a root injury or disease. Act quickly with a soil fungicide).
Pedant mode on:
There are in fact about three deciduous citrus varieties. Best known is the trifoliate orange which can can not only be planted outside but is sometimes used as a decorative shrub or even as a hedge plant.
Thanks,
I didn't know that.
I only used to work with a few citrus clients in central Queensland, so I agree that it was an assumption that all citrus were evergreen.
I'll admit, Citrus and Olive production wasn't really my thing (Macadamia production I loved).
The olives didn't produce too well because we were too far north, and the citrus industry collapsed around me due to an imported virus that crippled the industry (via forced government closure)..... Interesting times.
I was only trying to help with some basic plant principles that are general to all plant growth.
THanks for the helpful posts. I brought my small potted olive trees in last year, they lost all there leaves and nearly died but came back strong mid summer. THis year Ive decided to leave them out, well wrapped in bubble wrap and fleece. A friend did this last year and the tree survived well. THere's was a larger tree but if it's well wrapped and in a protected area in the garden that still gets some light Im hoping mine will be OK. It's too much of a pain to bring everything inside and they make a mess.
How about bamboo?
So here's my update after the winter.
We bought the tree in this year and left it in the kitchen / dining area (it's a small tree).
Apart from when I wasn't giving it quite enough water (better to err on the side of caution), it thrived inside and is going outside in a couple of weeks resplendent with all it's leaves.
Question: I seem to have 3 choices.
1. Put my olive tree in a cool but not freezing cellar with no light.
2. Wintergarten. Its bright, gets to 25 on sunny winter days, and down to 5 or so on cold nights. Which is quite cold but not freezing.
3. Leave it in the house where it's warm but unsure if this will stop the shedding of leaves which has started.
Background
I have a modest potted olive tree about 1metre tall from soil to the top of the tree. Despite a south facing balcony, I suspect the roots would freeze in deepest winter. And dry out as I won't be up there much.
So far I have brought it into the house, but not directly onto the warm floor which would heat and dry it out.
Then I moved it to the Wintergarten. But already (its not deep winter and so far has been cold enough to shock it to shedding it's leaves in droves over the last 2 days. About half are gone already )
Any advice?
#2.
They can take cold, even below freezing (though not extreme cold).
Around here people leave them outside, it only gets cold enough to severely damage or kill about once every 10 years, and even then most survive.
Tom
Anybody know of any shops/websites selling uv grow lamps? I can find really good ones in US but not in Europe..
Just put the fluffy white condom back on our little potted olive tree for the third winter. It's wintered well outside on the west-facing patio. We're at about 400m above sea level.
This. Ours survive quite happily in our glass abri de piscine, which gets pretty cold as it's not designed to seal out the wind, but also will get full sun for half of the day. The one key factor I've found is to ensure they're kept watered reasonably regularly throughout the winter. Even when it's not been sunny or warm they will use quite a lot. Once a week or so seems to work fine for ours, but they're in quite big pots with under saucers so will take for or five litres at a time.