Gardening with Gary

Gardening Advice from an Expert

Lilacs

Propagation:

Q. We have lilac trees in our back yard and our house is up for sale. When we move, is it possible to cut branches off these trees and replant them at our new house? Or should we just dig one up and bring it with us? I love the lilacs and will miss them. Would appreciate any answer you can give me.

A. Lilacs, like other hardwood perennials, bushes and trees, are difficult to propagate successfully from stems. It can be done though, using the most tender, green, healthy cuttings you can find. Rather, I recommend that you dig up an entire bush.

When we moved, my dad wanted to take some of the old lilacs from the backyard which he had gotten from relatives, so they were not only beautiful, but sentimental. Dig up a very wide space around the base, going at least as far out as the branches reach. Go down deeply, circling the bush, deeper and deeper. When all soil has been cut to 2 feet deep, carefully dig up the plant from all sides, getting as much root system as you can. Lay onto a large piece of plastic and move to the new location ASAP. Plant into a prepared hole and water in very well, with a slow, deep dripping.

You may need to stake the bush for a couple months until the roots take hold. Do not allow to dry, and if sunny, loosely drape some covering over it to reduce the sun glare and transpiration of water, which stress the roots. Do not fertilize until it is well-established.

For Darlene and other lilac lovers!

General Information:
Lilacs were introduced in France in the late 1800s at which time hybridizing was started by the horticulturists. We now have fragrant flowers with colors ranging from white and pale yellow to all shades of pink, mauve and purple. Most reach about 8' high and 6' wide. They can be grown solo or bunched as a hedge.

They prefer moist, humus-rich, well-drained soil in sun or light shade. They love cold winters which improve flowering. Prune right after flowering. Take out all dead, yellow, and weak growth, thus enabling more light and nutrients to get to the strong stems. This, too, will encourage much more flowering the next spring.

Korean Lilacs:

Betsybear writes~
How and when do you trim Korean lilacs for greatest productivity?

A. You have:

Syringia Meyeri 'Palabin'

Dwarf Korean - purple, lovely foliage, no suckers or mildew, fragrant, tolerates shade. Height 4-5'/width 5-6'.

A compact dwarf lilac with unique small foliage. A profuse bloomer with lavender flowers. Sun to part shade. Zone 5. Here are some good rules to follow when pruning lilacs. They are very important.

Many old lilacs are pruned back to just a few old stems by cutting off all the new suckers. These lilacs will bloom only at the top and the flowers will get smaller each year. A well-pruned lilac will produce larger flowers with blooms from the top to the bottom of the shrub. If you have an old lilac bush that has gone unpruned for a while it will take several years to return it back to its best.

The best time for pruning is right after the lilac has flowered usually in mid to late June. First, remove any dead branches. Count the number of main branches and select at least 1/3 of them to remove. This will open up the interior of the shrub and allow better air flow. Look for branches that cross or rub against each other and remove one of them.

If you want to make your shrub easier to mow around, cut out any branches that are bent over or growing downward. Check the suckers that are growing at the bottom of the bush. Cut off all but 3 or 5 of them. If you want to keep your lilac bush shorter and have larger flowers, remove any branch that is more than 3 years old but not more than 1/3 of bush at a time If you kept some old suckers from last year, cut out to the same number of branches allowed to grow this year.

Lilacs should be pruned immediately after they've bloomed in the spring. Dwarf Korean Lilacs require only a light pruning to maintain size and shape.

Good Lilac site:

http://www.raw-connections.com/garden/shrubs/lilac.htm

Gwen writes~ We planted three lilacs in our back yard. The first 1-2 years we got great blooms on two of the bushes. However, this year we have no blooms on one larger lilac - about 4' x 3' and only 1 bloom on another lilac about 3' x 2'. The lilac with no blooms receives sun from noon until sundown. The other one receives sun from early morning until about 2pm. These plants are about 2-3 years old and appear healthy otherwise. Also, I planted a wedgwood blue lilac 2 years ago. It was a small plant when purchased and is now about 3' tall and about 20" across. Every spring it gets tiny buds that look like it will be covered by lilacs, but then most of the ends of the branches turn brown and die. Is it budding too early and then being touched by frost? We have one nice bloom on the top of the 3' shrub. But what about the other branch tips? Any suggestions would be greatly appreciated. This plant faces south and receives at least 10 hours of sunlight per day.

A. There are many reasons besides weather which cause lilacs not to bloom as expected. The buds may have been inadvertently pruned off last year. Be careful, as the new buds for next spring form shortly after the flowers die back. The bush is immature: most varieties need 3-4 years to grow and develop before they produce their first major show of blooms. Transplant shock: if transplanted since the last blooming period, lilacs sometimes will miss a year, as they need time to recover. Soil imbalance: The pH should be measured, too much or too little of certain chemicals, possibly needing a supplement of dolomite lime. Recommended is a soil test through the local Cooperative Extension Service. Improper mix of fertilizers applied: flowering is encouraged with higher Phosphorus [the middle number of three in the fertilizer formula, check label]. Sometimes, people use high nitrogen, as a 30-10-10, which will produce fine green leaves while hindering blooming.

Assistance from: http://www.gardenersnet.com

Annie writes~ My daughter has a lilac tree that did not bloom this year. What would you suggest we use to encourage flowers? Many thanks for your help.

A. Usually when you do some hard pruning during a season, you will have plenty of new growth the next year -- but the blooms are sacrificed for several years. If that is the case, then be patient and your blooms will be back.

Lilacs perform in light shade but bloom the best when they have plenty of full sun. If they are getting that and you have not pruned them, try feeding them a bloom booster [high in the middle number]. You can mulch your shrub with well-rotted manure, since lilacs deplete soil of nutrients over time so need fertile soil. Prune lilacs by thinning unproductive growths where old bushes become overcrowded with too many branches and suckers. Prune after flowering but do not forget to take advantage of the incredible fragrance by taking cuttings for your friends and family. Usually a lack of sunlight can be an initial problem. A minimum of 6 hours of sun is needed per day. Too much nitrogen [first number, for foliage] can be a problem. Often lilacs are planted in the lawn and fertilizers used to green up lawns are too high in nitrogen. This causes beautiful green foliage but little bloom. Avoid high nitrogen fertilizer around the plant and use suggested fertilizer. No bloom after first year. Lilacs are sometimes purchased as bareroot or ball and burlapped plants. These will flower the same year but not reflower for 3-5 years. The flowers were made from the previous year and it is normal that the plant will have to make new roots and get settled in for a few years before it reflowers. The best way to purchase lilacs are containerized plants. These are lilacs that have passed at least 1 year in the container. They will have a complete root system and will reflower at an earlier age. Improper pruning time often is another problem. Some lilac lovers prune their plants at the wrong time. They should be pruned only when flowers are faded. Any other pruning will result in the cutting of flower buds.

Assistance from the International Lilac Society, Inc.

Vida writes~
I have access to a very old white lilac bush that I can try to grow new plants from. This is in middle northern Ohio, and the shrub is in bloom now. Is there a good way to take branches to try to root and will you show me the best way? Thank you for all the information that you give us in your section of Recipegoldmine. I take notes, but this is the first time I have made a request.

A. Since the lilac is a shrub, go about propagating it from stem cuttings taken in the autumn. To begin the stem-cutting propagation process, first select a good 4" piece off the top part of a healthy, non-flower-bearing shoot. If you cannot obtain a flowerless piece, remove whatever flowers there are on the shoot because they will slow down the rooting process. When you have found the ideal piece, cut it off at a very slanted angle and create scores just above and just below the vegetative eyes, making sure that the cut is horizontal at the bottom and on a slanted angle at the top. Next, apply a rooting hormone [available locally] to the base, taking care not to apply it heavily because excess powder will cause damage to the cutting. Carefully tap the powdered edge of the cutting against the edge of the hormone container to remove any excess. Plant cutting in a mixture made up of 1/2 peat/1/2 coarse sand. Using a spade, create a V-shaped trench about half the depth of your cutting and insert the bottom half, making sure the base has good contact with the soil. Fill any gaps in with soil, pat it down well and water it. If planting the cutting outside, it will be necessary to place a frame over it to protect it from the elements. For a potted version [pots are usually better for starting roots like this] use a bell clear glass cover or a plastic bag held over it securely with a string tie or rubber band. Allow one year to pass so that the roots are well developed before attempting to transplant the shrub.