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Gardening Answers Knowledgebase

Search Results for: Syringa | Search the catalog for: Syringa

Plant Answer Line Question

Keywords: Flowering of plants, Syringa

I have a lilac shrub that is about six or seven years old and blooms every other year. This seems very odd to me. Most lilacs bloom every year. Is blooming every other year normal? It is planted in optimal conditions and looks very healthy.


Quoted directly from Lilacs for the Garden, by J. Bennett (2002, p. 99): "Some lilacs, especially cultivars of the common lilac (Syringa vulgaris) bloom better, or only, in alternate years. Pruning the plant soon after it does bloom may encourage flowers the next year."
University of Nebraska Extension says that "removing the seed capsules soon after flowering has been reported to alter the every-other-year flowering cycle in some lilacs. This is because less energy goes into the current year's seed production and more into the next year's flower production. Some researchers agree with this recommendation and some do not. Removing seed capsules also improves the plant's appearance."

I could not find a list of which cultivars do this. You might consult the International Lilac Society to see if a list exists.

Another resource is the Hulda Klager Lilac Gardens (in Woodland, WA about 30 minutes north of Portland).

Date 2018-04-05
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Plant Answer Line Question

Keywords: Shrubs--Care and maintenance, Syringa, Transplanting

I have a dark purple lilac tree growing on the north side of my home. It does not get a lot of sunlight. I am wondering about replanting it somewhere else in the yard. When can I do this?


Lilacs should be able to tolerate moderate shade, according to The Plant Care Manual by Stefan Buczacki (Crown Publishers, 1993). You can move it to a sunnier location to see if it will thrive there.

The best time to transplant a lilac is before it leafs out (late winter, when it is dormant) but apparently they are somewhat tolerant of being moved at less-than-ideal times. The University of British Columbia Botanical Garden discussion forum also recommends transplanting lilacs in dormancy. Blooming should not be affected, unless your bush is already leafed out and in bud.

Date 2017-08-15
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Plant Answer Line Question

Keywords: Failure to flower, Syringa

I have a lilac bush given to me as a gift 13 years ago. I don't know the variety but the leaves look slightly different from the common lilacs I see. This bush has healthy looking leaves and while it has slowly put on growth over the 13 years it has never bloomed. I have tried adding ashes to the soil to make it more alkaline but nothing seems to work. What is the problem and how can I get this bush to bloom?


There are several reasons lilacs may fail to flower. Here is an excerpt (no longer available online)from North Dakota State University Extension horticulturist Ron Smith in answer to a question similar to yours:

Lilacs fail to flower because of insufficient sunlight, planted too deeply, too much nitrogen, improper pruning or winterkill of the flower buds. You said the lilacs get plenty of sunlight, but unless you used a lawn fertilizer to provide nutrients, it isn't likely too much nitrogen is the problem. If you planted too deeply, pull some of the soil back so the top of the roots are slightly exposed. If you pruned in July, then doing so removed the flower buds for the next growing season. If winter killed the flower buds, then hope for milder winters or purchase hardier lilacs.

Colorado State University Extension's article, "Renewing Lilacs," (no longer available online) offers other suggestions, such as late freezes,decreasing sunlight, and pest problems.

Sunset's Western Garden Book (2001 ed.) says that annual pruning is needed for optimal flower production. Most lilacs bloom on wood formed the previous year, so they should be pruned just after flowering. Remove the spent blooms and cut back to a pair of leaves. There are a few lilacs which bloom on new growth, so it might be useful to know exactly what type of lilac you have. You could bring in photos and samples to our Herbarium for identification.

Date 2018-04-04
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Plant Answer Line Question

Keywords: Bacterial diseases of plants, Syringa

I have a 'Palibin' lilac that appears to have a bit of bacterial blight. I have pruned out the diseased branches. Is it too late to spray to control the disease? I didn't do a dormant spray this year, and haven't done any preventive spraying to this point, either. If it isn't too late, what spray product would you recommend? What else can I do to keep the blight under control?


There are cultural methods of dealing with bacterial blight you should try before using any spray. The information below should help.

Washington State University Extension's HortSense website recommends:

  • Avoid injuring plants to reduce possibility of infection.
  • Avoid overhead irrigation.
  • Maintain proper plant nutrition. Healthy plants resist disease better.
  • Plant disease-resistant species such as Syringa perkinensis, S. microphylla, or S. vulgaris vars. 'Alphonse Lavallec', 'Crepuscule', 'Floreal', 'Guinevere', 'Jeanne d'Art', 'Lutece', 'Maud Notcutt', 'Mrs. W.W. Marshall', 'Rutilant', or 'William Robinson'.
  • Prune and destroy infected tissues as soon as they are noticed.
  • Space plants properly and prune to provide good air circulation. This will slow down spread of the disease.

Here is more information from University of California, Davis's Integrated Pest Management site. Excerpt:

"Bacterial blight is promoted by prolonged rainy springs. Symptoms may be more extensive in wetter areas. Prune branches showing dieback and severe blight. Space plants to provide good air circulation. Prune during the dry season when infection is less likely to occur. Do not wet foliage with overhead irrigation; do not overfertilize. Small plants can be protected to some degree by keeping them covered by plastic (or moved under plastic). Plant resistant species if available. If the disease is systemic or cankers appear on the trunk, the tree will probably die and should be removed. If the disease is confined to leaves, damage is not usually serious and trees normally recover. Sprays do not give reliable control."

Date 2018-03-01
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Plant Answer Line Question

Keywords: Lathyrus odoratus, Plant phenology, Pisum, Planting time, Syringa

It's already the middle of March and I'm worried that our soil is still too cold to plant peas (both edible and sweet). When is the correct time to plant them in the Seattle area?


Since weather patterns vary from year to year, it may make more sense to plant based on something other than the calendar date. An old adage says that it is time to plant peas when the lilac leaves are the size of a mouse's ear. This may sound quaint, but it turns out that the growth cycle of the lilac (Syringa) is an excellent indicator of temperature. Phenology is the science concerned with the timing of specific biological events, and lilac is among the plants often studied. Project BudBurst has additional information about phenology and climate change. The U.S. National Phenology Network is also a good resource.

If you don't have a lilac in your garden (or a mouse's ear, for that matter), Washington State University Extension says that a safe time for planting peas is usually mid-March, not so much because of soil temperature, but because in February the soil is often oversaturated, and your peas would rot in the ground.

Date 2017-08-24
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Plant Answer Line Question

Keywords: Flowering of plants, Syringa

Is there such a thing as a repeat-blooming lilac?


There is a relatively new (2009) lilac cultivar named 'Bloomerang' which is a repeat bloomer, described in this amusing article in Macleans.ca by Anne Kingston, entitled "Ever-blooming lilac wars." The article also mentions 'Miss Kim' and 'Josee' as repeat bloomers. Reblooming lilacs seem to appeal to some but to be an offense to others, who want lilac blooms to remain seasonal signifiers:
"The reason people love lilacs, of course, is because of their temporal timetable. Their first (and only) flowering is greeted with joy, tinged by the knowledge it will be fleeting, poetically so; no one has ever complained of being bored by lilacs. Tamper with that and you hit a primal nerve, as the Bloomerang clearly has."

Date 2017-05-04
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Garden Tip

Keywords: Flower arrangement, Syringa

Has the sweet aroma of lilacs tempted you to cut a few twigs for the house? Lilacs and other woody flowering shrubs can be disappointing in an arrangement unless they receive special treatment before they go in the vase.

As you cut the branches, place them in water. When you get them in the house, submerge the branches up to the flower in coolish water let them sit for 30 minutes or so, this is a sort of curing step and is very important. Before putting the lilacs into the new water, strip all but the most necessary leaves, and then break the stems at the bottom. They should be split at the ends to open the capillaries so water can reach the flowers. Ideally you should cut the flowers early in the morning, as that is the best time to cut and then don't arrange them till you get home from work. When you are ready to put the branches in a vase add a tiny bit of bleach and a little sugar to the water, its best if this water is also cool.

Then just enjoy them. Add more water daily keeping the level high and change it if the water gets cloudy or smelly, but the bleach should keep this from happening. Also moving them to a cool location at night, like a back porch helps even more. Processing woody branches takes more time but it is worth it in the long run.

Date: 2007-04-03
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May 31 2018 13:14:08