COLORFUL SPRING FLOWERING SMALL TREE
The attractive clusters of flowers and, sweet fragrance are its main attributes. In addition, the cut flowers are very showy in the garden and when used in flower arrangements. Relatively easy to grow, there are a few things you need to know to have best results growing Lilac's in your garden.
Lilacs need a bright sunny location in the garden, where there is good air circulation. I've grown them in part sun and they do all right, but not nearly as well as when they are in full sun. Don't crowd them with other plants; give them plenty of space in which to grow. Poor air circulation and/or crowding are apt to cause mildew problems.
Another requirement is good drainage. Lilacs will not tolerate wet feet, so drainage is exceptionally important. Where drainage it is poor, the problem must be solved before planting. In our garden we have blue-clay, so the only way we could solve the problem was to plant our lilac in a bed where we had mounded the soil, so the roots are above the poorly drained soil.
Container grown plants can be planted anytime through out the year. Bare-root plants are best-planted in late winter or early spring, at a time when the plants are dormant. (Late winter or earliest spring is also the best time to transplant them.)
I recommend preparing a large planting hole, so the roots have a chance to become established in fertile soil. I think the root area should be at least twice as wide and deep as the actual root system of the lilac you are planting. It's a good practice to mix ample amounts of compost, leaf mold or processed manure with the existing soil. Mix about 1/3 of one (or more) of these forms of organic humus with 2/3 of the existing soil. Large plants or newly transplanted lilacs may need to be staked to protect them from being wind-whipped during strong winter storms.
LILACS NEED LIME IN ACID SOILS
In the northwest, and other areas of the country, where the soil tends to be acid the plants will need lime. It is a good practice to lime the soil once or twice a year for the first year or two. Late fall to earliest spring are the two best times to apply lime, at the base of the lilacs.
Newly planted or transplanted lilacs should have the lime mixed into the planting soil, then commerce the additional applications as needed. There are several types of lime, so be certain to apply the amount as recommended on the label of the brand and type you use.
WHY DON'T MY LILACS FLOWER?
Good question! There are at least five basic reasons why they don't flower. 1) Is improper pruning, or pruning at the wrong time. 2) The plants are planted in too much shade. 3) The soil is too acid and needs to be sweetened with lime. 4) Poor drainage can also be a factor. 5) Feeding them with hot manure or high nitrogen fertilizers.
SUCKER GROWTH AROUND THE BASE OF THE LILAC
I think that too much sucker growth takes strength away from the parent plant. So you can simply dig the suckers and give them to friends, relatives and neighbors. (I use a manure, or pitch fork to do this job.) Each sucker is a new plant, and will eventually develop into a full size plant. Some gardener's simply snap off the suckers, but unfortunately they re-branch and make even more suckers, unless they are removed from the point where they originate.
Pruning lilacs is one of the most important steps in their care. Next year's flowers form during and after the current season's flowering period. So be careful not to prune off to much growth after the normal flowering season or you might be removing next year's flowers, too.
To remove dead flowers just snap each one off just below the flower stem. Several rings around the stem indicate this point.
The number one question I am asked about pruning lilacs is: 'My lilac has grown too tall and all the flowers are on the top tip branches where I can't see them, so can I cut them back severely, so I can see and enjoy the blooms'. My answer is yes! But don't chop them off all at the same height. Prune and shape the branches, trimming the outer ones lower and leaving the center ones taller. My rule is never trimming them back more then 1/3, less if possible.
If you have an old lilac that needs to be rejuvenated, remove about ¼ of the oldest main stocks each year. This will help the tree, yet will not deprive you of flowers during any year. Keep in mind that a well-maintained young bush should never need severe pruning.
All severe pruning is done during the winter dormant season months of November, December, January or February.
I don't think lilacs are heavy feeders, but when feeding is needed, use a rose or garden type fertilizer. Select and use a brand that has the micronutrients included. It's important that they get the Iron, Zinc, Magnesium and all the other minerals.
The best way to fertilize an established plant is to punch a few holes around the base of the established tree. These holes should be made at the drip-line of the tree and about one-foot beyond. Make the holes about 6 to 10 inches deep and space them about 12 to 15 inches apart. Use a pipe, crowbar, root feeder or similar tool to make the holes. Then put the correct amount of fertilizer down each hole. And last, but certainly not least, apply water to dilute the fertilizer to keep it from burning the tree roots.
This can be an occasional problem. Primary means of control is pruning to improve air circulation. A tree fungicide can also be used. Be certain to read and follow label instructions.
This is a rather common lilac problem. The insect often lays it eggs on the mid-rib or vein of the leaf. The larva lodges between the layers of the leaf, then as the insect matures it tunnels through the leaf. Finally it crawls out and folds the leaf to form a cocoon.
It is not uncommon for the larva to winter-over in the fallen leaves. Therefore, it is important to rake and destroy the leaves in the fall.
If your plant has this problem, I think it helps to spray the surface soil, around the base of the tree, in early to mid-April, with a natural insecticide like 'Neem'. Then new leaves should be sprayed as they mature.
This is an occasional problem in some areas, it is first noted when the tips of the leaves appear to wilt and bend over, then die back. Brown or black spots often appear on the leaves. This problem is aggravated in wet summers or when soil around the plant tends to remain wet.
If there is a dieback, cut out the affected areas. Then try to provide better drainage for that plant.
ONE LAST WORD
Lilacs are fun, beautiful, fragrant plants to grow and some of the comments here seem to make it sound like it is a difficult plant to grow that's not true! In fact, it is a relatively easy plant to grow. But, in trying to cover all the different questions I get, it seems more difficult then it really is, to grow this showy plant.