Can l buy established lily of the valley plants in pots from a garden center and put in the garden in early spring? Will it flourish in full sunlight? If not, can I plant the bulbs in early spring?
Yes, you can certainly plant out your Lily of the valley after danger of frost.
You should plant in a partial sun location.
This article has more information.
http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/management-of-leaf-spot-diseases/
The temperatures have been in the 50's. Today it was 75 degrees which felt really warm. The rest of the week it will be in the 50's. When will lily of the valley start to grow? My sister was worried that the plants were not growing yet or starting to grow.
Were these established plants or a new plant?
The soil warms much more slowly and in most cases perennials will emerge when the wake up and are ready!
I read your article about killing Lily of the Valley. We want to put up a pen for our dogs but a good portion of it has Lily of the Valley growing in it. Your article mentioned glyphosate herbicide (Roudup). Our concern is how long would we have to wait before it would be safe for our dogs to be in that area. Do you know? Thank you. Our pet safety is of upmost concern.
By law most herbicides must break down in soil within 14 days.
This article has more information.
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/how-long-does-weed-killer-last-in-the-soil.htm
I have lily of the valley "invading" my mint garden. Will the lily of the valley make the mint poisonous??
No, Lily of the Valley will not kill your Mint.
This article will help you.
https://www.gardeningknowhow.com/ornamental/bulbs/lily-of-the-valley/lily-of-the-valley-control.htm
Why don't my lily of the valley flower?
It may need to divided or fertilized. This article may help
http://www.gardeningknowhow.com/ornamental/bulbs/lily-of-the-valley/growing-lily-of-the-valley.htm
I didn't get flowers just the leaves this year what went wrong?
They could be overcrowded or nutrient deficient. Try dividing them in fall and using a phosphorus rich fertilizer like bone meal, for blooms next spring
Mine has not bloomed for a few years. What can I do? They are in partial shade and good soil.
I have had this same issue and have had success giving them a feeding of Bone Meal in the early spring.
https://www.gardeningknowhow.com/ornamental/bulbs/lily-of-the-valley/growing-lily-of-the-valley.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/bone-meal-fertilizer.htm