How to Grow Lilacs

Guide Note Lilacs are deciduous shrubs or trees which produce flowers in the spring or early summer. Once they are established, they require minimum care, providing you know the proper methods for how to grow them.

Table of Contents

• Introduction
• Step 1: Types of Lilac
• Step 2: Planting Lilacs
• Step 3: Watering and Fertilizing
• Step 4: Pruning and Rejuvenating
• Step 5: Pests and Disease
• Conclusion
• References

Growing Lilac Tips

1. Not all lilacs are lilac-colored; they can also be white, blue, pink or yellow.
2. If your lilac doesn't flower, it either needs more sun or needs pruning.
3. Lilacs will not grow in soggy soil.
4. Lilacs need at least six hours of sunlight.
5. Most lilacs like USDA Hardiness Zones 3-7, but some can grow in warmer or colder areas.

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Introduction

• Lilacs originated in Asia and Europe, and have been cultivated for over 300 years.¹ They are ideal for hedges, borders, and tall screen plants because of their growth habit.² However, lilacs are most famous for their flowers, which they produce every spring in abundant quantities. If you have ever wanted to grow your own lilacs, then there is no time like the present. Even someone with a black thumb will find lilacs an easy plant to care for.

Step 1: Choose a Type of Lilac

• 

  Lilacs are both beautiful and relatively easy to cultivate. (Creative Commons photo by Matt McGee)
  All lilacs belong to the genus Syringa, but that does not mean they are all the same. The characteristics of different lilac species make them more suited for different areas. For example, most varieties of lilacs will not do well in warmer climates such as USDA Hardiness Zones 8 or 9, located in the southeastern United States.³ You also want to consider how large you want your lilacs to get. Some varieties stay as small as 4 feet, while others grow close to 30 feet. Selecting the right species of lilac is important if you want to have lilacs with fewer problems and minimal fuss.

Syringa vulgaris – Common Lilac

1. Has the longest midseason blooming time.⁴
2. Very hardy and drought resistant but more susceptible to disease and pests.¹
3. Slow growing.²

Syringa laciniata – Cutleaf Lilac

1. Has smaller "cut" leaves that give it a finer texture.¹⁷
2. Heat tolerant and mildew resistant.¹⁸
3. Easy to grow; adaptable.¹⁹

Syringa meyeri – Meyer Lilac

1. Begins flowering liberally when it is small.²⁰
2. Maintenance and trouble free; mildew resistant; Requires little pruning.^{21 22}
3. Cultivar 'Palibin' (Palbin Meyer or Korean dwarf) can be grown in Zone 8 and parts of Zone 9.²³

Syringa microphylla – Littleleaf Lilac

1. Produces smaller flowers mid to late season.²⁴
2. Heat tolerant and mildew resistant.²⁵
3. Long flowering period.²⁶

Syringa oblata – Early or Largeleaf Lilac

1. One of the first lilacs to bloom in the spring.²⁴
2. Moderate growth rate.²⁷
3. Easy to grow and adaptable.²⁸

Syringa patula – Korean or Manchurian Lilac

1. 

   Different lilac varieties will blossom in different sizes and colors-- not always just lilac-colored ones. (Creative Commons photo by Hans Splinter)
   'Miss Kim' cultivar is resistant to powdery mildew.¹
2. Vigorous.²⁹

Syringa pekinensis – Pekin Lilac or Chinese Tree Lilac

1. A tree lilac that has a vigorous growth and peeling bark.³⁰
2. Very late blooming.³¹
3. Does not flower for years after planting.¹
4. Drought tolerant.³²

Syringa reticulata – Japanese Tree Lilac

1. Blooms for two weeks in the late spring or early summer.³³
2. Resistant to scale, powdery mildew and borers.¹
3. Moderate growth rate; capable of reaching heights of 25 feet.³⁴

Syringa villosa – Late Lilac

1. Flowers smell like cloves.¹
2. Late blooming.³⁵
3. Susceptible to diseases such as blights, leaf spots, wilt and ring spot virus.³⁶

S. vulgaris x S. chinensis – Chinese Lilac or Rouen Lilac

1. Capable of being grown in Zone 8 and parts of Zone 9.²³
2. Blooms mid to late season.¹
3. Grows faster than common lilac.²
4. Has few disease or insect problems.³⁷

S. vulgaris x S. oblata – Hyacinthiflora Lilac

1. Cable of growing in Zone 2.²³
2. Early blooming.¹

Syringa x persica – Persian Lilac

1. Has smaller flowers than common lilac on drooping branches.²⁴
2. Can have problems with powdery mildew and other diseases.³⁸
3. Rapid growth rate.³⁹

S. vulgaris x S. prestoniae – Preston Lilac

1. Grows in Zone 2.²³
2. Late blooming.²
3. Very hardy.²⁴

• YouTube: Hulda Klager Lilac Festival (Time: 3:57)

Step 2: Planting Lilacs

• Once you have choose a type of lilac, you will need to purchase a few for your garden. In general, you will want to choose nursery-grown plants that are 2 to 4 feet tall.²⁴

When to Plant

• Lilacs can be planted in the spring or fall. It is usually better to plant lilacs in the fall after the leaves have dropped. This will give the roots a chance to establish themselves before the leaves appear. You can also plant lilacs in the spring before the buds start to unfold.²⁴ If you are planting in early spring or fall, choose container-grown plants. However, if you are planting later in the spring, choose field-dug plants.²

Location

• Lilacs can be grown in most settings, but there are some areas that are better than others.²⁴ Here is a list of the ideal conditions for most lilacs:

1. Sun: Lilacs need at least 6 hours of full sun a day.⁴⁰ More sun is better than less since too little sun can cause the lilac not to flower.³¹
2. Air Circulation: Good air circulation is necessary to reduce chances of any fungal disease.⁸
3. Space: Lilacs need at least 6 feet between plants for a hedge, 10 to 15 feet for a shrub.² Lilacs need to be at least 5 feet from any buildings because their root systems can damage foundations.¹
4. Drainage: Lilacs need good drainage. Soggy soil causes the roots to rot and will eventually kill the plant.³¹
5. pH level: The ideal pH level for lilacs is 6.5 to 7.0.² However, lilacs will tolerate pH levels up to 8.5 if the conditions are right.¹ If necessary, you can raise the pH level by adding dolomitic lime, bone meal or ground limestone.^{8 24 2}

How to Plant

1. Dig a hole. The hole should be slightly deeper than the pot and large enough to fit the roots without bending or breaking them.^{40 24}
2. Remove the lilac from the pot and score the roots. For bare root lilacs, soak the roots in a bucket of water.^{40 41}
3. Work a bucket of peat moss and a cup of 5-10-5 fertilizer into the soil. You can use cow manure as an alternative fertilizer.²⁴
4. Set the plant so that it is 2 to 3 inches deeper in the hole than it was at the nursery.²⁴
5. Fill in the hole and water the lilac thoroughly.⁴⁰
6. Add a 2 to 3 inch layer of mulch around the lilac to help protect the roots, control weeds and conserve moisture.² Deep bark or wood chip mulch is better than stones.¹ Mulching will also prevent heaving, or when the soil alternates between freezing and thawing, which is deadly to your lilacs.²⁴

Step 3: Watering and Fertilizing Lilacs

• In general, lilacs are easy to care for and require very little maintenance.

1. You will only need to water your lilacs while they are young or during severe droughts.⁸ Most lilacs are drought-resistant.⁴⁰
2. If your lilac is growing vigorously, it does not need fertilizing. Otherwise, you can add about 1/2 pound of 5-10-10 fertilizer per 25 square feet of soil in the early spring or mid-fall.²

Step 4: Pruning and Rejuvenating Lilacs

• Lilacs will not require pruning for the first five years after they are planted or once they reach 6 to 8 feet high.¹ At that point, they will need to be properly pruned or they will become overgrown and may eventually stop flowering.⁸ If that has already happened to your lilac, then you will need to rejuvenate it, which is a more severe form of pruning.

Pruning

• You need to prune your lilac so that it is has approximately seven to twelve stems of different ages and thickness that don't cross each other.¹

1. As soon as the flowers fade, deadhead the lilacs.⁸ This will prevent seedpods from growing, which require a lot of energy and can cause the lilac to flower poorly the following year.⁴²
2. You should prune immediately after the lilac stops flowering.⁴²
3. You will want to remove:
   1. Diseased or dead branches.⁸
   2. Branches that are three or more inches thick.¹
   3. Small, twiggy branches.¹
4. Prune branches just above a bud.⁸
5. You may need to thin out top growth to increase the amount of sunlight that reaches the buds at the center of the plant.²
6. If your lilac has become too tall, try cutting one or two of the older limbs at ground level with a saw.⁴⁰

Rejuvenating Lilacs

• If your lilac has stopped flowering or is overgrown, it needs rejuvenating. Rejuvination is a three year process that involves removing one-third of the branches each year down to the ground. This should be done in the late winter by removing the least productive branches.⁸

• A second way to rejuvinate is to cut down the entire plant about 6 to 8 inches from the ground in March or early April. The following year, select several strong shoots as the framework of your shrub and remove all the other shoots at ground level. Then, cut the retained shoots just above a bud, to encourage branching.⁴³

Step 5: Dealing with Pests and Disease

• Here are a few of the more common diseases and pests that can affect your lilacs.

Don't let pest infestations ruin your lilacs. (Creative Commons photo by Dvortygirl)

• Powdery Mildew: If you notice a dusty white color on the leaves of your lilac during the late summer, then you have a problem with powdery mildew. This is the most common problem for lilacs but not harmful to the plant.^{2 42} Treat it by spraying plants with horticultural oil or by dusting the plant with a fungicide.^{8 24} You can reduce the likelihood of your lilacs getting this fungus by pruning them to allow good air circulation, planting them in the sun or spraying your lilacs with potassium bicarbonate.^{42 1 2}

• Oystershell Scale: If the branches of your lilac look like they have small oyster shells stuck on them, your plant has been infested with parasitic insects.² Prune out any heavily affected branches.⁴² Then, when the temperature is above 60 degrees, spray with Diazinon or Malathion.

• Lilac Borer: Lilac borers are moths that burrow into the branches of the lilac to lay their eggs. They are very common east of the Rocky Mountains and on stressed plants.¹ Look for empty holes and prune out any affected stems.² Proper pruning by removing the oldest stems will minimize your problem with this pest.⁴² You can control them by spraying the main trunk and branches every three weeks starting in early May with a borer spray.²⁴

• Lilac Leaf Miner: The lilac leaf miner, or Gracillaria syringella, is a common pest in the East.² These moths lay their eggs on lilac leaves. Once the eggs hatch, the young larvae eat the inside of the leaves and leave blotch-like markings on the leaves. The leaves will eventually blacken and separate.³¹ You will need to spray a systematic insecticide such as neem, Diazinon or Orteene at the first sign of this pest.¹ This should kill the insect within one to two days.³¹

• Bacterial Blight: Bacterial blight is a disease that often occurs when the spring temperatures fluctuate and occur with cold rains. Blotches will appear on the leaves before they turn brown and wilt. Prune out all branches that are affected immediately about six inches below the infected area. Sterilize your pruners after each cut with 70 percent rubbing alcohol.³¹ You may also want to use a Bordeaux mixture or copper fungicides to protect your lilacs when conditions are favorable. Apply them just before bud break.¹

Conclusion

• Lilacs are a wonderful addition to any garden. You will probably discover that the biggest problem you have is how to keep your neighbors from stealing all your flowers. Luckily, lilacs produce enough that you will have enough to share.

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References for How to Grow Lilacs

1. ↑ ^{1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18} Montana State University: Growing Lilacs in Montana  
2. ↑ ^{2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15} University of New Hampshire: Growing Lilacs (May 9, 2000)  
3. ↑ USNA: USNA - USDA Plant Hardiness Zone Map: South-Midwest US
4. ↑ Martha Stewart: Lilacs
5. ↑ Martha Stewart: Syringa vulgaris 'Adelaide Dunbar'
6. ↑ Martha Stewart: Syringa vulgaris 'Angel White'
7. ↑ The National Gardening Association: Lilac Blue Skies
8. ↑ ^{8.00 8.01 8.02 8.03 8.04 8.05 8.06 8.07 8.08 8.09 8.10} Martha Stewart: Lilacs
9. ↑ Martha Stewart: Syringa vulgaris 'Firmament'
10. ↑ Martha Stewart: Syringa vulgaris 'Krasavitsa Moskvy'
11. ↑ The National Gardening Association: Lilac Lavender Lady
12. ↑ Martha Stewart: Syringa vulgaris 'Little Boy Blue'
13. ↑ Martha Stewart: Syringa vulgaris 'Marie Francis'
14. ↑ Martha Stewart: Syringa vulgaris 'Sensation'
15. ↑ Farmington Gardens: Lilac Varieties  
16. ↑ Martha Stewart: Syringa vulgaris 'Wedgwood Blue'
17. ↑ Michigan State University Extension: Syringa laciniata--Cutleaf Lilac
18. ↑ NC State University: Shrubs: Syringa laciniata
19. ↑ UConn Plant Database: Syringa laciniata
20. ↑ UConn Plant Database: Syringa meyeri
21. ↑ Michigan State University Extension: Syringa meyeri--Meyer Lilac
22. ↑ OSU Pocket Gardner: Syringa meyeri
23. ↑ ^{23.0 23.1 23.2 23.3} Garden Ideas: Lilac Time
24. ↑ ^{24.00 24.01 24.02 24.03 24.04 24.05 24.06 24.07 24.08 24.09 24.10 24.11 24.12 24.13} Utah State University: Growing Lilacs  
25. ↑ Michigan State University Extension: Syringa microphylla--Littleleaf Lilac
26. ↑ Oregon State University: Subperba Littleleaf Lilac
27. ↑ NC State University: Shrubs: Syringa oblata
28. ↑ UConn Plant Database: Syringa oblata
29. ↑ NC State University: Shrubs: Syringa patula
30. ↑ Michigan State University Extension: Syringa pekinensis--Pekin Lilac
31. ↑ ^{31.0 31.1 31.2 31.3 31.4 31.5} The International Lilac Site: Lilac Information page
32. ↑ NC State University: Shrubs: Syringa pekinensis
33. ↑ Martha Stewart: Syringa reticulata
34. ↑ OSU Pocket Gardner: Syringa reticulata
35. ↑ UConn Plant Database: Syringa villosa
36. ↑ Kemplar Center for Home Gardening: Syringa villosa
37. ↑ Kemplar Center for Home Gardening: Syringa x chinensis 'Lilac Sunday'
38. ↑ Kemplar Center for Home Gardening: Syringa x persica
39. ↑ NC State University: Shrubs: Syringa meyeri
40. ↑ ^{40.0 40.1 40.2 40.3 40.4 40.5} HGTV: Selecting, Planting, Pruning and Propagating Lilacs
41. ↑ Fox Hill Lilac Nursery: How to Properly Plant your Lilac
42. ↑ ^{42.0 42.1 42.2 42.3 42.4 42.5} Plant Palette: Lilacs (April 20, 2008)
43. ↑ University of Nebraska–Lincoln: Lilacs – Selection & Pruning

How to Grow Lilacs Books

• Amazon.com: Lilacs: The Genus Syringa by John L. Fiala
• Amazon.com: Lilacs: A Gardener's Encyclopedia by John Fiala & Freek Vrugtman