My lilac bush did not drop its leaves this winter.
Your Lilac to not harden off and abscise the leaves.
If this is a young tree, it will likely be fine. Wait for new growth to began pushing off the old leaves.
Care for the plant normally.
https://www.gardeningknowhow.com/ornamental/shrubs/lilac/lilac-care-growing-and-planting-lilac-bush-plants.htm
https://www.gardeningknowhow.com/ornamental/shrubs/lilac/lilac-plant-fertilizer.htm
We have a lilac tree but can seem to grow anything underneath it. Is there anything you could suggest?
Here are some articles that will help you.
https://www.gardeningknowhow.com/special/shade/ground-covers-for-shade.htm
https://www.gardeningknowhow.com/ornamental/trees/tgen/planting-garden-beneath-trees.htm
https://www.gardeningknowhow.com/ornamental/groundcover/gcgen/ground-covers-under-trees.htm
https://www.gardeningknowhow.com/ornamental/trees/tgen/tips-for-growing-grass-under-a-tree.htm
Can you plant a lilac bush near a vegetable garden? Or will it make everything taste like lilac?
The lilac bush won't transfer its taste to the vegetables, so there's no problem there. However, a lilac planted too close to the vegetable garden will compete with the vegetables for water and nutrients, and the leaves might shade the garden, depending on where exactly it is placed.
A shrub's roots will generally extend out one and a half times the width of the shrub at maturity, so it's best to place it at least that far away.
My older lilacs have no buds. What should I do for them?
As this article explains, older lilacs can have a decline in blooms because lilacs bloom better on younger wood. You may be able to promote more flower bud growth in the future by pruning to promote more growth of new wood:
https://www.gardeningknowhow.com/ornamental/shrubs/lilac/lilac-bush-not-blooming.htm
How do I apply phosphorus to my plants? Do I water after I put it down? For lilac bushes around 5' tall how much do you think I should use--no flowers. Same for hydrangeas.Thanks much--Live in Flemington NJ.
The easiest method to add phosphorous to your plants soil is to use Bone Meal.
Adding good organic compost to your soil around the plants will also help.
Follow the directions on the packaging for the Bone Meal product that you choose.
I generally scatter the recommended amount and rake into the top soil. Then water in.
Here are some articles with more information.
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/phosphorus-plant-growth.htm
https://www.gardeningknowhow.com/ornamental/shrubs/lilac/lilac-bush-not-blooming.htm
https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/hydrangea-not-blooming.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/bone-meal-fertilizer.htm
We just bought land with a quite a few lilac trees on it. But they have no smell. I love lilac's but would like them to have smell. What do I need do???? I plan on pruning them after they bloom. I grew up in a house that had old lilac trees in the yard and they always smelled great.
This article has some ideas why your Lilac's may be lacking fragrance.
https://www.gardeningknowhow.com/ornamental/shrubs/lilac/lilacs-no-scent.htm
I have an old dark purple French lilac that only has 2 to 3 blooms a year. I am planning to prune a little after blooms this spring and then fertilize in Feb. of '18. Bone meal will be a component. Does that sound right? This bush was my mother's. Her aunt gave it to her in the '50s.
Old lilacs will often not bloom or have very few blooms. Yes, adding bone meal and pruning to encourage new wood to grow is a good plan. You can follow one of the two pruning plans described in this article:
https://hortnews.extension.iastate.edu/1993/2-10-1993/lilac.html
The plan should cause flowering to improve over the next 3-5 years.