Windows [BUG] Greenhouse wood border seems to impede the growth of mango fruit trees

[OptiStreak]

I am trying to grow mango fruit trees in the greenhouse. I decided to plant my mango trees in the red and green-circled areas below.

According to the wiki,

Neither the greenhouse walls nor the wood border around the crop rectangle alone impede fruit tree growth

I wanted to minimize the number of iridium sprinklers in the planting area, so one of the configurations involved putting an iridium sprinkler on the wooden border near the red-circled area. However, after putting the iridium sprinkler on the border near the red-circled area, I got messages saying "Your mango tree failed to grow last night." The green-circled area, which had no iridium sprinkler grew faster than the mango tree in the red-circled area. After removing the iridium sprinkler from the wooden border near my mango trees, I didn't get the message anymore. However, I would like to put iridium sprinklers on the wood border, but this can't be done until after the trees are grown.

Game Version: 1.5.6, Steam version
In-Game Language: English
Single/Multiplayer: Single Playe