I have 16 lavender plants which were planted in May of this year and all grew very well with fragrant flowers. My question is whether it is possible to move these plants to another location in the garden; and if so, how and when is the best time to do it?
Lavender is best transplanted in either spring or early fall. In most areas, it is a bit too late into fall to be transplanting now. I would recommend waiting until the spring to move them.
This article will help you with transplanting the plant:
https://www.gardeningknowhow.com/plant-problems/environmental/learn-how-to-avoid-and-repair-transplant-shock-in-plants.htm
How do I grow this as a hedge? How do I grow separately along my driveway? With a bit of space in between?
For Margaret Roberts Lavendula, you can space them about 2-3 feet apart for a hedge. For a normal planting, you would space them 4-6 feet apart and for a hedge, you would want this tighter (hence 2-3 feet).
In order to maintain it as a hedge, you will need to prune regularly. Once a year for a taller style hedge and twice a year for a more compact hedge.
I brought a lavender plant (Munstead) inside for winter. I pruned it a bit, and instead of throwing away the cuttings, I dipped them in root hormone and stuck them in a mix of peat and sand. They are growing roots now, but it's still February, and I live in Maine. I'm wondering if I should transplant them into a soil mixture until I'm ready to plant them outside. What do you think?
Yes, I would do that. They will grow well in soil until it is time to plant them outdoors.
My new home has lavender and thyme in the front flowerbeds. They've not been pruned (in 3-4 years). The lavender is 2. 5 feet high with 1/2-inch woody stems. The thyme looks like underbrush, wirey and dead about 4 inches deep.
You will need to do a pruning process called rejuvenation. These articles will explain how to do it:
https://www.gardeningknowhow.com/edible/herbs/thyme/pruning-thyme-plants.htm
https://www.gardeningknowhow.com/edible/herbs/lavender/pruning-lavender.htm
Three different times now, I have tried to sow lavender seeds. However, each time I attempt this, I get an initial sprout roughly an inch tall, then it quickly falls over and dies before the second leaves form. I have yet to produce seedlings that I can move to a bigger pot. This last time I kept the soil moist, but not waterlogged, and it happened again. What am I doing wrong? When sowing lavender, do I need to water less once they sprout? Do they need more than 6 hours light? What is the big secret? Please help I need any advice you can give.
I would recommend less water and when you do water, water the seedlings from below. It sounds like the seedlings are damping off, so a little fungicide in the soil will help as well.
I read somewhere that lavender does not grow well in areas where the humidity is high 80%. Is that true? Is there a variety that will do well in this climate?
High humidity makes it more susceptible to fungal disease, plus areas with high humidity tend to get a lot of rain, which they don't like. If you take steps to control the fungus, by applying fungicide to the soil, and you make sure it has excellent drainage, you should still be able to grow it.
I want to know why my lavender plant never blooms.
The soil most likely lacks phosphorus. Plants need phosphorus to bloom. Add a phosphorus rich fertilizer to the soil. This article will help as well:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/phosphorus-plant-growth.htm