Best Fertilizers for Lilacs 2022 – Buyer’s Guide

Best Fertilizers for Lilacs

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.

Based on user reviews and feedback, we filtered down to the best ten fertilizers to help your lilacs grow.

Selecting the Best Fertilizers for Lilacs [current_date format=’F, Y’]

IMAGEPRODUCT
  • Dimensions: 1 x 1 x 1 inches
  • Weight: 4.2 ounces
  • Brand: Jobe's
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  • Dimensions: 4.2 x 13.5 x 7 inches
  • Weight: 8.15 pounds
  • Brand: Miracle-Gro
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  • Dimensions: 2 x 5 x 7 inches
  • Weight: 4 pounds
  • Brand: TreeHelp
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  • Dimensions: 7.3 x 3.7 x 11.3 inches
  • Weight: 4.6 pounds
  • Brand: BioAdvanced
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  • Dimensions: 10 x 4 x 4 inches
  • Weight: 4 pounds
  • Brand: Dr. JimZ
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  • Dimensions: 3 x 5.5 x 9.5 inches
  • Weight: 3.2 pounds
  • Brand: Scotts
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  • Dimensions: 8.1 x 3.8 x 10.7 inches
  • Weight: 5.35 pounds
  • Brand: Down To Earth All Natural Fertilizers
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  • Dimensions: 22 x 14 x 3 inches
  • Weight: 25.5 pounds
  • Brand: Grow More
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  • Dimensions: 8 x 4 x 8 inches
  • Weight: 8.11 pounds
  • Brand: General Hydroponics
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  • Dimensions: 4.1 x 7.5 x 10 inches
  • Weight: 4.9 pounds
  • Brand: Osmocote
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1. Jobe’s Hanging Baskets & Potted Plant Fertilizer Spikes: Best Fertilizer for Dwarf Lilacs

Jobe’s Hanging Baskets Review

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.

Pros
  • Fertiliser inserted in soil so no waste from run-off
  • Slow release of nutrients
  • Other formats with varying NPK available
  • Easy to use – no mixing involved
Cons
  • Nutrient-rich which will not suit all soil types
  • Shape (if visible) may be tempting to dogs

2. Miracle-Gro Shake ‘N’ Feed Flowering Trees & Shrub Plant Food: Best Long Lasting Fertiliser

Miracle-Gro Shake ‘N’ Review

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.

Pros
  • Easy-to-use
  • Healthy mix of organic ingredients
  • Long-lasting
Cons
  • Often used as a complement increasing its relative cost

3. TreeHelp Premium Fertilizer for Lilac: Best Lilac Specific Fertiliser

TreeHelp Premium Fertilizer for Lilac Review

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.

The nitrogen’s slow release mitigates against weak new growths and enhances cell walls to defend against insect pests and adverse weather.

Pros
  • Meticulously researched “recipe”
  • Lilac specific
  • Long-lasting due to slow release ingredients
Cons
  • This fertiliser hasn’t yet become a big seller

4. Bayer Advanced 12 Month Tree & Shrub Protect & Feed Granules: Best Insect Pest Defence Fertilizer

Bayer Advanced Review

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.

Pros
  • Highly effective against insect pests
  • Three formats available
  • Rainproof
Cons
  • Does not kill all insects but is effective against lilac’s enemies
  • Not to be used in all US states (check before purchase)

5. Tree Secret Liquid Fertilizer: Best Fertilizer to maintain Healthy Soil

Tree Secret Liquid Fertilizer Review

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.

Pros
  • Environmentally friendly
  • Natural ingredients
  • Endorsed by microbiologists following extensive tests
Cons
  • Large quantity required for effectiveness
  • Has been found to be slow-working

6. Scotts Continuous Release Evergreen, Flowering Tree & Shrub Fertilizer: Best Easy-to-Use Fertilizer

Scotts Continuous Release Evergreen Review

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.

Pros
  • Easy to use
  • Various sized bags available
  • Provides continuous release of nutrients
Cons
  • Composition favors acidic rather than alkaline soil
  • Some users find the mix too strong

7. Down to Earth Organic Fish Bone Meal Fertilizer Mix: Best Organic Fertilizer

Down to Earth Organic Fish Bone Meal Fertilizer Mix Review

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.

Pros
  • No synthetics used
  • OMRI (Organic Material Review Institute) approved
  • Compostable packaging
Cons
  • No potassium so check pH reading of soil to ensure balanced composition
  • Application is more onerous than others – mix into soil before watering

8. Grow More 5010 All Purpose Fertilizer: Best High NPK Fertilizer

Grow More 5010 All Purpose Fertilizer Review

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.

Pros
  • Balanced macronutrient rich mix
  • Versatile in application and location
  • Easy to use
Cons
  • Some users find the slow release a bit too slow
  • The high macronutrient content may be too much for some terrains

9. General Hydroponics Flora Series: Best Comprehensive Fertilizer

General Hydroponics Flora Series Review

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.

The NPK nutrients within the set are augmented by purified mineral salts and silic acid and the set allows the grower control over all stages of a lilacs life. And we love the groovy design on the labels.

Pros
  • Adaptable: match to all stages of a lilac’s development
  • Provides a thorough supply of nutrients
  • Scientifically researched
  • Well established
Cons
  • Users report that the liquid can be easily spilled
  • May take some experimentation to arrive at ideal usage

10. Osmococte Smart Release Plant Food (Flower & Vegetable): Best Value for Money Fertiliser

Osmococte Smart Release Review

Osmocote Smart Release Plant Food will allow lilacs to get the nutrition which they need when they need it. The unique smart release element is facilitated by the nutrient granule’s composition.

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.

Pros
  • Good value
  • Shell makes this odorless and suitable for indoor use
  • Slow release of nutrients a huge benefit for lilacs
  • Long-lasting
Cons
  • Granules can be washed away
  • Needs careful analysis of soil for compatibility

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

Types

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!

Dimensions

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.

Life Span

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.

Maintenance

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.

Fertilizer background

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.

Disease

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.

Conclusion

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.