My mint plant sometimes have strong stems and on certain days it becomes weak and flimsy. I tried to use stings to tie the mint plant together but it didn’t work. It’s the one on the right. Is there anything i can do to make it better? Also, the lemon balm on the left started to be like that today.
This will happen when the soil is allowed to dry out too much, then get watered quickly. Sometimes the extreme differences in moisture will cause weak stems, temporarily.
The other common cause of weak stems will be a lack of light. This will be a little more consistent, though. They won't perk up after being flimsy in this case.
Watering will need to be done as the soil dries down to about 2 inches. Below that will be allowed to remain moist, and above that will dry out between waterings.
The plants will act a little more evenly with a modification of watering habits.
This article will help:
https://www.gardeningknowhow.com/special/containers/container-plant-watering.htm
A moisture meter may help, as well:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-moisture-in-plants.htm
I have also just ordered a daphne plant but no instructions. Can it be planted out now or kept in greenhouse til later?
Lemon balm can be pruned to harvest or to invigorate its growth. It can be invasive if left to reseed. Trimming off the flowers right away can prevent a lot of the reseeding. It will die back with a hard freeze, but should return in spring, in multiples if it reseeded. I looked up your average weather, and it doesn't traditionally freeze, so you could go ahead and plant it outside. It can be grown indoors as well. Since you have a greenhouse, you could keep it there for the winter.
Here is information on lemon balm and daphne. Daphne is hardy in your area, but since it's wintertime, I would leave it in the greenhouse, too, for the winter.
https://mastergardener.extension.wisc.edu/article/lemon-balm-melissa-officinalis/
https://www.gardeningknowhow.com/edible/herbs/lemon-balm/growing-lemon-balm.htm
https://www.gardeningknowhow.com/ornamental/shrubs/winter-daphne/daphne-plant-types.htm