The lilac is one of the great harbingers of summer. This fragrant and colorful shrub blooms from mid-May which makes it a sure-fire sign that we’re about to enter the season of sunshine and sustained daylight.
Lilacs are renowned as an easily cultivated flower and for being low maintenance in your garden.
Choosing the right fertilizer can help give your flowers a serious boost.
Jobe’s Hanging Baskets & Potted Plant
Best Fertilizers for Lilacs in Our Rating
- Easy to use, no special training required
- Unpleasant odor unlike other fertilizers
- Guaranteed Result
- Provides flowers with continuous power
Selecting the Best Fertilizers for Lilacs April, 2021
1. Jobe's Hanging Baskets
1 x 1 x 1 inches
|2. Miracle-Gro Shake 'N Feed Flowering|
4.2 x 13.5 x 7 inches
3. TreeHelp Premium Fertilizer for Lilac
2 x 5 x 7 inches
|4. Bayer Advanced 701700 12 Month |
7.3 x 3.7 x 11.3 inches
|5. Tree Fertilizer, Tree Secret 64oz|
10 x 4 x 4 inches
|6. Scotts Continuous Release Evergreen|
3 x 5.5 x 9.5 inches
| 7. Down to Earth Organic Fish Bone Meal Fertilizer Mix 3-16-0, 5 lb|
8.1 x 3.8 x 10.7 inches
Down To Earth All Natural Fertilizers
|8. Grow More 5010 |
22 x 14 x 3 inches
|9. General Hydroponics Flora Grow|
8 x 4 x 8 inches
|10. Osmocote Smart-Release|
4.1 x 7.5 x 10 inches
1. Jobe’s Hanging Baskets & Potted Plant Fertilizer Spikes: Best Fertilizer for Dwarf Lilacs
Jobe’s Hanging Baskets & Potted Plant Fertiliser Spikes aren’t your normal fertiliser. Instead of something in a bag or a can, it includes 18 bullet-shaped fertilizer spikes which are inserted in the soil.
The spikes are sold in packs with various NPK formulae pertinent to different species: potted plant & hanging baskets; bulb & perennial; azalea, camellia & rhododendron; rose.
We’ve chosen the Hanging Basket & Potted Plant pack for its compatibility with dwarf lilacs. This brand has a 9-12-6 NPK ratio so it is rich in all macronutrients especially nitrogen and phosphorus thereby stimulating growth and strengthening roots.
2. Miracle-Gro Shake ‘N’ Feed Flowering Trees & Shrub Plant Food: Best Long Lasting Fertiliser
Miracle-Gro’s standing in the plant food sector means it is no surprise Shake ‘N’ Feed lies among the best-selling brands. A granular fertiliser simply scattered around the lilac tree/shrub and lightly raked into the soil will not tax anybody’s gardening aptitude.
It is available in various versions – All-Purpose and Rose & Bloom being just two – and we have selected Flowering Trees & Shrub as the one best suited for lilacs.
The NPK ratio of 18-6-12 leans towards nitrogen as the dominant macronutrient with organic ingredients (bone meal, kelp, etc.) providing a nice balance in this slow release fertiliser which feeds plants for up to three months.
3. TreeHelp Premium Fertilizer for Lilac: Best Lilac Specific Fertiliser
Treehelp, founded in 1999, is an intriguing player in this field. It holds an academic perspective on all things green; dispensing advice and learned opinion in addition to actual products so you can be sure their products have been thoroughly researched.
Their flagship fertiliser is a generic blend of granular macro and micronutrients which is then customized for an extensive range of plants and trees.
Treehelp Premium Fertilizer for Lilac’s blend of macro- and micronutrients foster root development and act as a preventive against disease.
4. Bayer Advanced 12 Month Tree & Shrub Protect & Feed Granules: Best Insect Pest Defence Fertilizer
Bayer Advanced 12 Month Tree & Shrub Granules is a powerful defender against the insect pests who can wreak havoc on lilac shrubs. There are three options with this brand – concentrate, extra-strength concentrate and the granular version.
We have opted for the latter: it is the least expensive, allowing the purchaser to test it on their particular circumstances.
Insects such as borers and scale are attracted to lilacs and can be the agents of wholesale destruction which makes this product a comfort to gardeners as it effectively eradicates both of these pests for a year. A low NPK mix (2-1-1) provides fertiliser for nutritional needs but its real potency for lilac growers lies elsewhere.
5. Tree Secret Liquid Fertilizer: Best Fertilizer to maintain Healthy Soil
Tree Secret Liquid Fertiliser is a fermented blend of 64 natural ingredients combining to enrich the soil. It feeds the nutrients required for the health and longevity of lilacs into the soil through spraying.
Lilacs can sometimes be provided with too much nitrogen leading to exuberant foliage but reduced blooms. Tree Secret addresses this with a nutrient cluster providing ideal conditions for the plant to grow and to ward off diseases…and it does so organically.
6. Scotts Continuous Release Evergreen, Flowering Tree & Shrub Fertilizer: Best Easy-to-Use Fertilizer
Scotts Continuous Release Fertiliser provides an easy and effective way to feed lilac plants with the nutrients to enhance root and foliar development. The granules are simply poured from a resealable bag directly into the soil and raked through to ensure even distribution.
With a NPK ratio of 11-7-7, this fertilizer contains generous amounts of the macronutrients which facilitate growth and strong roots. Its carefully formulated mix won’t burn plants and lasts for two months.
7. Down to Earth Organic Fish Bone Meal Fertilizer Mix: Best Organic Fertilizer
Down To Earth has been at the vanguard of the organic movement since 1977 and this natural synthetic-free fertiliser is emblematic of their innovative produce. It eschews the usual NPK mix by excluding potassium, instead favoring primary and secondary plant nutrients and fish bone meal.
Down to Earth’s organic credentials are further enhanced by the ultimate gardening renewable material – compostable packaging.
The usage of fish bone meal improves the alkaline content of the soil making it ideal for lilacs. With 16% phosphorus ingredients, the mix is also 14% calcium as an aid towards healthy lilacs.
8. Grow More 5010 All Purpose Fertilizer: Best High NPK Fertilizer
Grow More 20-20-20 Fertilizer is a heavyweight in every sense. The bag contains 25lb of granules which can be dissolved in water or applied directly. It is versatile as it can be applied directly onto leaves or into the soil in either a soluble or solid state.
Nutrient-rich, the mix has a high concentration of nitrogen, phosphorus and potassium and this combination facilitates growth, strength and longevity of lilacs. The composition allows the nitrogen component to be released in a staggered fashion for optimum benefit.
9. General Hydroponics Flora Series: Best Comprehensive Fertilizer
The General Hydroponics Flora Series is an established member of the range of fertilisers suitable for lilacs. First devised in 1976, the set features three bottles of concentrates which together furnish lilacs with all the nutrients needed for development and continuity.
Flora Grow (NPK 2-1-6) helps the roots to develop; Flora Micro (5-0-1) stimulates growth and Flora Bloom (0-5-4) helps to increase the number of blooms.
The Flora Series was developed by a former senior chemist at NASA, an organization which knows a thing or two about how to utilize climactic conditions to one’s advantage.
10. Osmococte Smart Release Plant Food (Flower & Vegetable): Best Value for Money Fertiliser
It is coated with a semi-permeable shell which allows water to permeate and dissolve the nutrients before releasing them into the soil. This system factors in temperature changes with commensurate release of nutrients.
The Smart Release plant food allows the abundant macronutrients (NPK 14-14-14) to be absorbed by the soil gradually – a major boon to lilac plants. It makes the brand very good value and long-lasting.
Guide to Fertilizer for Lilacs
Lilacs may sound too good to be true: eye-catching flower which blooms prolifically, fills the air with a heady aroma, bridges the gap between spring bulbs and summer color, requires minimal maintenance and all this from a shrub or tree with the potential to outlive us. Well, syringa (its botanical genus name) is all of the above.
A Few Basic Facts about Lilacs
There are twelve recognized species of lilac but the one which people across Europe and North America will be familiar with is the common lilac (syringa vulgaris). Other popular variants include the Dwarf Korean, Persian, Chinese, California, and Tree lilac. In this article, we will use “lilac” as a generic term, but readers should assume that the common lilac is the one being referred to unless otherwise stated.
One further clarification on terminology: we will use the term lilac interchangeably to refer to the shrub, tree or flower itself but the one being referred to should be apparent. Ok, let’s go!
The lilac shrubs most people identify grow to somewhere between 8 feet and 20 feet (2.4 m to 6m). Outside of this range, the two extremes are dwarf lilac (4 feet or 1.3 m) and tree lilac (30 feet or 9m). When the lilac blooms in late spring, it produces an abundance of small aromatic flowers which can be any hue of purple, pink, blue, white, cream or magenta.
Location and Conditions
Lilacs are hardy plants which not only survive winter but actually benefit from harsher weather: cold winters can lead to a profusion of blooms in the spring. Befitting their status as adaptable and robust, lilacs can grow in most types of soil with a preference for neutral to slightly alkaline ground (a pH reading between 6.5 and 7.5). They especially thrive in well-drained conditions with a gentle incline or elevation.
The partiality for well-drained conditions stems from an inherent dislike for wetlands or territory where water tends to gather. If the site selected lies in a drought-prone region, the plant would need occasional watering.
Lilacs can be grown in pots, but the planter is restricted to smaller varieties such as Korean Dwarf lilac which grows to about 4 feet (1.2m). Dwarf lilacs favor cooler climes and bloom bounteously.
A lilac will take up to three years from planting before blooms appear, assuming that you bought a shrub from a nursery or garden store. If the lilac was planted from seed, the wait for blooms will extend by up to another two years. If you go down this road, winter or early spring is the optimum time for planting. Once established, lilacs have longevity indelibly written in their DNA and shrubs/ trees have been known to survive more than 100 years.
Low-maintenance is the description frequently applied to lilacs. These resilient plants just get on with it provided they receive a basic amount of TLC. It is advisable to prune and deadhead them when the blooms fade during the summer to facilitate new growth. Some gardening experts maintain that pruning in alternate years will suffice but that smacks of taking the laissez-faire approach too far and probably stems from the common lilac’s tendency to bloom prodigiously every other year.
A more comprehensive revamp of the plant can be undertaken if there is a desire to renovate. Bear in mind that a lilac pruned back to the basics will need all that 3-5 years to recapture its fragrant and colorful splendor.
All effort expended in tending to lilacs will be rewarded, especially so when it comes to applying fertilizer. This is the area where research allied to utilization of acquired knowledge will reward itself manifold.
A glance at the range of fertilizers available for use on lilac plants can be a head-spinning experience. It can get really technical with analysis chemistry, pedology (study of soils in their natural environment), and edaphology (how soils interact with living plants) to derive the precise fertilizer mix required. Or to put it another way, apply a few basic rules to inherent knowledge of your garden’s soil.
Fertilizers enhance growth and provide nutrients to complement those already in the soil or to overcome any nutrient deficiency. There are two types of fertilizer – organic and inorganic. Organic fertilizers are derived from plant or animal sources such as seaweed, fish bone, bone meal, etc. They are slower in achieving results but provide a more harmonious balance with nature.
A layer of fertilizer should be applied under each plant in the spring and topped off with mulch which facilitates the retention of moisture. If there are extended periods without rain during the summer, the plants should be watered…but not too much; lilacs respond badly to being waterlogged. Similar restraint should be exercised in the quantity of fertilizer dispensed as lilacs will not bloom if over-fertilized.
Composition of Lilac Fertilizer
The composition of fertilizer is contained in NPK, the ratio of the percentage of three macronutrients nitrogen (N), phosphorus (P) and potassium (K) in the mix. So, if a fertilizer bag has a 20-20-20 NPK ratio, the composition will be 20% each of nitrogen, phosphorus and potassium with the remainder containing micronutrients (inert ingredients such as copper, chlorine, zinc, etc.) which are required in soil but in lesser quantities.
Of the three nutrients in NPK, Nitrogen is deemed the most important as it ensures a plant has sufficient protein to foster growth. Phosphorus promotes root development and is particularly important during a plant’s formative stage. Potassium helps plants to withstand adverse weather and diseases.
5-10-10 is the NPK ratio applicable to most lilacs as too much nitrogen leads to lush foliage but a deficiency of blooms. However, the more discerning gardener with localized soil knowledge should calculate the desired ratio; inevitably, there will be a fertilizer matching that formula.
Like all plants, lilacs can fall prey to diseases which come in three forms:
- Insects – lilac borers can damage the trunk of a lilac tree and should be eradicated through use of a mild insecticide.
- Pests – mice or voles can gnaw at the bark of stems and should be dealt with as the gardener sees fit.
- Blight – powdery mildew is the most recurring blight to visit lilacs. It takes the form of a powdery mound which occurs in humid weather or if the plant is not pruned effectively. A general fungicide should solve problem.
We hope the task of selecting fertilizer/plant food to boost your lilacs has been eased by our assessments and testimonials, all based on independent evaluations.
Frequently Asked Questions
Is Liquid or Granular fertilizer best?
This is subjective. Some fertilizers are pellets which should be immersed directly into the soil and covered in mulch, some are added to water whereas others come in liquid form and simply need to be sprayed on to or around the shrub. Each will be formulated for specific conditions.
Can lilacs survive indoors and if so, is there a specific fertilizer for them?
It probably comes down to space. Lilacs do spread themselves ergo most species need to be grown outdoors. Dwarf lilacs are compact and represent the best interior option and there are fertilizers appropriate for them. See our product list!
Do lilacs always bloom?
Usually but adverse weather conditions and/or a lack of maintenance can lead to an absence of blooms. Applying the correct fertilizer in timely fashion will go a long way to preventing such an outcome.