Winterizing your tropical fruit trees

We in Southern Arizona, specifically the Tucson area have some challenges when growing tropical fruit trees. More so than the Phoenix area. The main challenge, next to scotching summer sun, is our occasional night of temperatures below 35. For many tropical trees temperatures below 50-40 degrees is where most will shut down growth. Temps under 35 and many will start to die. How can we avoid this? Below are some instructions and tips on how to care for your tropical trees over our "winter" months  

Should you start fires in your yard on freezing nights?

I think most of you know the answer to that... The above is an example of what orchards in colder climates will go through to protect their fruit trees. This of course is an extreme example. We should never have to, well let me rephrase that as, something I would never suggest. you do. Especially in todays age of fires...  

Sooo, if I shouldn't burn down my neighborhood, how else do I keep these trees warm?

There are many ways to help keep your tropical investment warm on cold nights. Most of these methods will spare your neighbors homes too, so win, win. 

Grow your trees in a greenhouse...

We know most of you do not have access to a greenhouse, let alone one large

enough to grow a tropical paradise. If you have a greenhouse we are all envious

lol, but I wont go into this option as all you really need to do is add a heat source

or means of retaining heat through the night if you have a greenhouse and

you'll be golden, err green.

Greenhouses can be high dollar units you order on the internet that are comp-

lete kits, or they can be built out of free sourced items you find on Craigslists

or Facebook Marketplace. Pallets and old windows can make a beautiful green-

house. You can also build on out of simple 2x4's and warp it in plastic for the

winter. In summer you pull the plastic and put up shade cloth. A hybrid of those

systems could also be used.

Is watering on a cold night a good idea?

You would think the answer to this question would be no. In actuality it depends on the type of tree you are trying to keep alive. Some tropicals, such as banana could rot if watered during the winter. If the tree goes dormant it may not be a good idea to water. Especially if cold snaps are forecast for multiple days/weeks. Water WILL act as a thermal insulator, helping keep the ground temps above freezing. For trees like guava, curry, figs, apples, peaches, and many other "woody" trunked trees its perfectly fine to water deeply on a super cold night. It will help hold the heat in the ground overnight. DO NOT do this multiple days in a row as you could oversaturate the ground and cause your tree to die. 

Trees such as papaya, atemoya, banana and anything with a "spongy" trunk that's not woody should not be watered during the winter. Its best to know your trees very well before attempting this on all of them.

Plant near structures

Planting your trees near structures like houses, concrete or block walls and even near/under other trees (if the tree is not deciduous) can be a great way to help. You have to research your tree to make sure its roots are not considered invasive. If they are you will want to keep that tree away from structures and walls. 

Frost Cloth/Plastic Structures

Frost cloth is a preferred method to create a warm environment for your tropical trees. This is done

by creating a PVC or wood structure that is at lease 1' wider and taller than what your trying to

protect.(dont go too much larger as the goal is heating that space). You then secure frost cloth to

that structure on the tops and 4 sides. On a super cold night you can add a shop light, or incan-

descent bulb inside the structure to help add heat through the night. As you may guess depending

on the winter your electric bill can suffer. We recommend a temperature controlled plug. This plug

turns off over 45 and on under 45 degrees. Perfect for making sure your tropicals are kept alive on

freezing nights without running your electric bill up. As an alternative to frost cloth you can use a

6 mill or thicker plastic to cover your structure. The downfall to this is it traps moisture and lots of

heat during the day if not removed. It is a acceptable alternative to frost cloth. You should just

remove it through the day, or create a hinged, or removable top so that it can breathe throughout

the day. 

DeWitt N-Sulate is a great name brand frost cloth that holds up to a couple years of wear. Its sold 

locally at a couple nurseries. Contact Magic Gardens Nursery in Tucson AZ as they are a local

supplier.1-520-885-7466. If you need help building a frost protection structure you can reach out to

Beautanical Gardens at BeautanicalGardens@gmail.com, or visit their site at Beautanical Gardens 

Banana plant protection

Protecting banana tees can be done the same way as above, by utilizing a structure over your 

bananas and adding a heat source.

Another method, one of two show to the right, is to cut the banana plant to the 3-4' tall level.

You then create a wire cage around the banana tree that is 18-24" around. You then fill that structure

with straw, or dried leaves. This will create an insulative layer around the stalk of your banana. You

will want to top this structure with a plastic top so that water does not soak into the trunk of the tree,

or create soggy environment around the stalk of your plant as that can quickly rot and kill your

banana. 

The second style shown to the right is to wrap that trunk in frost cloth. This is a less effective

method that the cage method above, and is only recommended if temps drop below 32 for a short

period of time.

A third method is to cut the plants down to 6-10" tall, and cover those trunks and around those

trunks to protect the corm (root ball of the banana plant) from freeze. You accomplish this by

mulching heavily over the trunk of the plant, and 24-30" around the trunk of the tree with 12+" of dry 

mulch. 

DO NOT WATER YOUR BANANAS OVER WINTER! They will rot very easily and do not need watered

when in this dormant state. Banana plants will start to enter this dormant state when temperatures

drop on average below 55 degrees.  

General Protection

In addition, or better yet, before covering your trees and plants a with any of the above methods one of the easiest and most efficient ways

to help your trees and plants deal with our heat and cold is by adding a very thick layer of natural mulch and organic material. 

When adding mulch around your trees a very important thing to remember is that if your mulch is from freshly mulched trees you will want to:

1-Let it sit for a couple weeks to start breaking down before putting it on your trees and plants.

2-Apply it in thin layers over a couple weeks to achieve that ideal 12-18"+ of mulch that trees love in our desert.

 

The reason for doing this is because as newly mulched material breaks down it lets of a tremendous amount of heat (Just do a google search for "Tanks Landfill Fire Tucson". That place catches fire all the time if they are not diligent about pile control. Mulch will get so hot it can self combust in the right conditions. Not likely in a 12-24" pile, but to be safe its good to layer lightly in the beginning or let your new chips age a bit before adding them around trees. 

As always if you have any questions or comments reach out to us on our FaceBook page @TucTropics, or email us @ TucsonTropicals@gmail.som.

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