Freeze Protection For Mirlitons–That Works!

The following blog was submitted by David Hubbell from Mobile. I asked him to explain how he saved his family heirloom mirliton from the recent early freeze, the worse one in 112 years. Every year we are losing locally grown varieties because of climate changes; droughts, early frosts, intensive precipitation events and flooding. If we are going to preserve out heirloom varieties, we need to plan for these challenges. David started from the beginning with a trellis he could easily and quickly protect from the frost or freeze. The old saying was that mirlitons take care of themselves; they use to, but not anymore.

Lance

Freeze Protection for Mirlitons

By David Hubbell

To say I was a bit concerned when I received an email titled “Frost Alert…” from mirliton.org on November 8^th is a bit of an understatement. In Mobile, Alabama the typical first frost dates are November 21^st-30^th, which is what I have typically experienced over the past 10 years of growing mirlitons here. However, to get down below freezing for more than 6 hours and nearly two weeks early was almost unprecedented. Of course, we have had similar predictions in the past that would change as the forecast got closer to the predicted date, however, the local experts were telling us this one was serious.

On the following Sunday, I tuned in to the Plain Gardening with Bill Finch, our local gardening guru on the radio, to get his take on the forecast. Just like mirliton.org, Bill was extremely concerned on what was going to happen to the fruits, vegetables, and ornamental plants of the area should we see the predicted 12 hours of 25-29 ^oF temperatures. Bill is also a great supporter of the mirliton effort and we have spoken frequently over the last several years on the subject. In fact, he even lamented on the air “what was David Hubbell going to do with his mirliton?”

So, what was I going to do? Well, evaluating the situation and looking over my experience of the last 10 years I figured I had at least three possible options:

1. Cut the vine back to 2” above the surface and cover with mulch
2. Try the sprinkler method suggested by Lance Hill at mirliton.org or
3. Try to provide enough cover and heat

Since I had only picked two mirliton and had a lot of blooms with plenty of growing time left, I decided against option 1. While option 2 made logical sense to me, the area of my structure and the types of sprinklers I had didn’t lend themselves to this method; plus, due to the proximity to my driveway I may actually be creating a slipping hazard with the water. Therefore, I decided by default to go for option 3. I had some previous attempts at this over the years with mixed success and I had somewhat designed my mirliton support structure for such an enhancement.

Preliminary Steps

Before even considering protecting against a freeze, I had planted my vine in a well-drained location about 25 feet away from a big water oak with a decent canopy. This location is also heavily shaded by some of the neighboring trees and even three navel orange trees I planted nearby around the same time. Unbeknownst to me at that time, this probably has provided a bit of an infrastructure needed to help keep heat released from the ground trapped beneath the canopy and warm the mirliton vine. The first few years of growing mirliton was basically trying to mimic visions I had of old T-pole clothes lines I thought I remembered seeing mirliton grow on as a kid. I did this with a nice, but inadequate trellis and a long rope tied to the water oak. After the massive amount of plant growth during the first few years I realized I needed a “beefier” structure. Seeing pictures of similar structures created from folks in the New Orleans area I choose to create a system with six 4×4 posts separated by 1×4-12 planks lengthwise and 1×4-8 widthwise, and using reinforcing wire and small 1×2 railing pieces on top (see Figure 1.) The main advantages of this structure for me was a place for the vines to grow across the top while allowing the fruit to hang down so I could easily walk under it and inspect and pick. Plus I know had a structure that could now be easily reinforced with coverings and heater/heat lights if needed.

FIGURE 1. Mirliton Structure

Materials Used for Freeze Protection

1. 20 ft. x 25 ft. Clear 4 mil Plastic Sheeting – quantity 2
2. Old flannel King Size Bedsheets -quantity 4 (more preferable)
3. Heavy Black Yard Bags full of leaves – quantity 5 (more preferable)
4. Incandescent Heat Lamp – quantity 1 (2 or 3 may be preferable)
5. Halogen Lamp – quantity 1
6. 360 Surround Indoor Heater Black 1500W – quantity 1
7. Swimming Pool Cover – 15 foot diameter – quantity 1 (3 or more preferable)
8. ½” thick plywood -enough to cover top
9. Clamps of various size

Freeze Protection Steps

Two Days before predicted frost:

1. Rake all of the leaves and loose material away from the mirliton structure. This will allow as much heat to absorb into the ground, which will in turn be released back at night during the freeze.
2. Fill as many black plastic yard bags as possible and allow them to absorb the heat from the sun.
3. If your vine has grown beyond the structure, pick any mirliton that are of a useable size on that part of the vine, then pull all of the vines up under the structure. In my case this basically killed this portion of the vine, but the plan is to protect the main plant as much as possible, so for me this turned out to be somewhat of a sacrificial act.

Day before predicted frost:

1. Place black plastic bags around the base of the vine to form an insulating barrier from the cold.
2. Cover leaves and vines with as much flannel or thick cloth as possible. NOTE: You don’t want the plastic material to directly touch the leaves. There will still be damage without the cloth and only the plastic.
3. With assistance, take one of the 20 ft. x 25 ft. clear plastic sheeting and cover the cloth allowing about a 2 foot over lay onto the ground to prevent a way for the cold air to “short circuit” the protective barrier. Use as many clamps as possible to secure to the wooden structure.
   1. Repeat with other roll of plastic in a similar manner. NOTE: If your structure is bigger, you may need more rolls.
4. Once again with an assistant’s help, cover the structure with the pool cover(s) especially if you didn’t have enough sheets to cover the plants.
5. Position heat lamp(s), light(s), and heater. NOTE: Do not place them directly against and cloth, plastic, vegetation, or dried vegetation. This could cause a fire to the structure or heat damage to the plant.
6. Place plywood on top of the structure. This serves three purposes:
   1. Added insulation
   2. Traps in heat from lamps/heater.
   3. Protection from rain. In my case, rain was predicted with the incoming cold front. In years past I learned that the rain will collect on the plastic and cause the barrier to be breached thus thwarting all of your efforts.
7. Finally, place heavy objects such as pots full of dirt, bricks, cinder blocks, etc. around the over hanging plastic to ensure the winds doesn’t gust up underneath. Also secure any openings where the cords going to the lights or plastics overlap with smaller clamps. Try to make the covering as secure and tight to prevent any breaches of cold air.

Day after predicted frost:

1. Once freezing temperatures have passed and outside conditions get in the mid-30s ^oF, unplug heat sources.
2. Remove as much as covering as possible so as not to damage the plant now that danger of frost and freezing has passed. At a minimum open up enough to allow ventilation of the mirliton vine.
3. Inspect the plant for damage.
4. Water the vine and apply a gallon of a water-soluble vegetable fertilizer.

Final Thoughts

The previously describe method was based off of my 10 years of mirliton growing experience. I feel I was quite fortunate to have escaped any significant damage. I would like to add that if the freezing temperatures would have been predicated for more than 12 hours, I would have been hard pressed to try either methods 2 or 3. While it is nice to extend the growing season for the mirliton, I feel it is more important to preserve the Louisiana heirloom varieties as best as possible. In the case of prolonged freezing weather or after the typical fruiting season has passed (mid December) that means method 1. While it is always a sad day at the Hubbell Household when I have to cut the mirliton vine back, I know that by March I will start to see sprouts returning and if I am lucky will be treated to a small springtime crop.

Thanks for taking to time to read my thoughts and please feel free to contact me at rpcajun2r@gmail.com.