We are going to start our 2021 diary with a little experimentation. We haven’t grown watermelon for a number of years and have decided that we would like to try a couple of plants this year. After doing some research online we have decided we would like to learn to graft watermelon. Some of the benefits of watermelon grafting would be disease resistance and plant vigor. This will be totally new for us and we do not really know how it will turn out. We may have to grow traditionally if we can’t master the grafting process. Apparently, one of the most important things to have after grafting is to have some sort of healing chamber for the newly grafted plants to go into. This healing chamber needs to be kept at and a very high relative humidity at first and then slowly reduced over the course of a week. The grafts need to be in the dark for the first two days and then slowly introduced to light a little longer each day.
The picture below shows our newly built healing chamber (24” X 28” inside dimensions) with the control box on the right.
________________________________________________________________________________________________________
The control box contains a SHT2000 temperature and humidity controller. It is wired in such a way so that one half of the outlet supplies power to the humidifier and the other half delivers power to the heater. It is very easy to make changes to the settings to either raise or lower the heat/ humidity inside the box. The red display is the temperature and the blue is the humidity.
________________________________________________________________________________________________________
We started some seeds January 15 just for practice. We decide to use bushel gourd as the rootstock mainly because it was available to us. Unfortunately, we had very poor germination of the bushel gourds and we were only able to get 3 seedlings started from that batch. Today, we decided to try the first practice grafts. There are a number of different grafting techniques, but we decided for this first try to go with the one cotyledon graft.
This is one of the bushel gourd seedlings. They were not the healthiest looking plants but it’s all we had.
________________________________________________________________________________________________________
Here is the same plant after the true leaves as well as one of the cotyledons were cut off on an angle down the stem.
________________________________________________________________________________________________________
Next, is the watermelon scion that was cut on the same angle to hopefully match the cut on the bushel gourd.
________________________________________________________________________________________________________
Next a grafting clip was put on the stem
________________________________________________________________________________________________________
The seedlings were put inside the healing chamber and covered to keep light out. The humidifier is just a small bottle cap humidifier that fits inside a water bottle. The heater is a germination mat under the wire rack. The black probe on the top right is connected to the SHT 2000 controller. It measures both the temperature and the humidity.
It’s been a week since we grafted the watermelon on to the bushel gourd rootstock. The plants are looking a little rough, but they are still alive. We kept them in the dark for two days at 95% relative humidity. After that we introduced light into the healing chamber and we believe we might have injured the plants by using a light that was too intense. We also reduced the humidity inside the box a little each day.
_____________________________________________________________________________
Here is a closer look at the plants. The watermelon cotyledons on this first plant have completely died off. It looks like the true leaves are still growing.
_____________________________________________________________________________
The next plant shows the same die back of the watermelon cotyledons. This plant also has regrowth of the bushel gourd that shouldn’t be there. We need to make sure that the growing tip of the bushel gourd is completely removed next time. We will cut away the new growth of the BG as well as the dead cotyledons and continue to grow these plants to see how they do.
__________________________________________________________________________
This last plant seems like our best one. The cotyledons are a little yellow and you can see a little bit of BG regrowth just above the grafting clip that needs to be trimmed off. Overall we are happy with the results, so far. At least we are learning. We have started another batch of seeds and will try another set of practice grafts in a few weeks. We may attempt the hole insertion graft next.
__________________________________________________________________________
We have the healing chamber set up into a growing chamber right now with glass top and light. All the grafts are still growing well and we have some new plants just starting for more practice grafting.
____________________________________________________________________________
This is a look inside of the box with new plants in various stages. First grafts are in the back right
___________________________________________________________________________
All the grafts that we did a little over two weeks ago look good. This is a closer look at one of them.
____________________________________________________________________________