This post may contain affiliate links. If you make a purchase using one of these links it means we may earn a small commission at no extra cost to you. Learn More

Fertilizing Lilacs: When, How & Which Fertilizer To Use

The Lilac flower blesses our eye vision with different shades of blue, purple, white, pink, magenta, and many more. The ideal location for lilac is being sunkissed with a bit of alkaline to neutral soil. 

The distinctive and intoxicating scent represents sophistication in the ambient. It’s a good sign that doesn’t require too much care, involving the fertilizing process. As always, the exception is here with nutrient-poor places.

The lilacs symbolize purity and innocence, and it’s believed that lilacs bring a positive vibe together in a spiritual sense. 

When to Fertilize Lilacs?

It is not necessary to fertilize your lilac plant until after the second year after planting. When active growth is about to start, use a general-purpose fertilizer with a ratio of 10-10-10.

Every year, lilacs lose their leaves, so the canes rouse from sleep in the first few weeks of spring. Limit your plant’s fertilization to once per year. If lilacs receive too much fertilizer, they are most likely to fail in blooming.

I would like to give some additional information about the source of fertilization. 

Coffee grounds and grass clippings are also excellent sources of nitrogen providence. Use in moderation since an excess of nitrogen in the soil can lead to not satisfying blossom.

The ideal soil conditions for lilacs are a little bit alkaline between 6.5–7.0 pH, moistened, and good drainage. The soil may become more alkaline by adding bone meal to it. 

Last but not least, lilac plants dislike acidic soil. Epsom salts can be used in the dormant season to encourage blossoming.

How To Fertilize Lilacs?

The lilac flower usually grows insanely on cool summer days, but in hot and humid environments as well. What we can elicit from this is lilac does not need too much feeding. When picking fertilizer look for high potassium and low nitrogen ratio.

Here are some professional tips on fertilization:

  • Fertilization shows the best result when it’s applied in the early spring, right before the new and fresh growth.
  • Fertilize the lilac flower throughout the second year, not the first.
  • Using bone meal can create more alkaline in the soil.
  • Apply fireplace ash on all sides of the drip line.
  • Epsom salt can be super beneficial and will cause more flowering. 

Warning: If you pick chemical fertilizers over organic, please use protective gloves and a mask. Read the manufacturer’s instructions and follow the rules accordingly.

Best Fertilizers For Lilacs

1. Shake ‘N Feed Flowering Trees and Shrubs Plant Food

The multi-purposed Shake ‘N feed Flowering contains all natural microbes in the soil and all ingredients provide zero harm to the lilac plant.

You can use it for all flowering trees, shrubs, and many more acidic plants with no exceptions. Fertilize the lilac plant and many kinds of flowers in the early spring and at the end of the season. 

For in-ground plants, try to spread the fertilizer evenly in the soil and do not let the ingredients touch either the leaves or trunk. Give them a good watering.

For container plants mix the fertilizer at the same time of planting and if the lilac is already established, apply lightly and water to end the hungriness.

The NPK is an 18-6-12 ratio and contains small amounts of calcium, sulfur, magnesium, and water-soluble iron. 

The brand claims that the chances of burning are impossible if you follow step-by-step instructions.

Here is how to use it. apply to dry and do not mix with water previously. Avoid using on wet leaves or a stem. Regarding the size, the amount changes. For example, 2ft 1/2 tsp is ok, and for 8ft 3.4 cups will do the perfect job.

Check Price On Amazon

2. Lilly Miller All Purpose Planting 

Again, we have multi-purposeful plant food which ideal fertilizer for the lilac plant. It ensures slow release for lush and makes steady growth. Works best with flowers, shrubs, and veggies.

With the NPK 10-10-10 ratio, the natural ingredients are provided from 4 distinct sources, and other small amounts of nutrients last much longer the keep the plant full. As a result, you will get a beautiful bloom and healthy root.

Here’s how to use the Lilly Miller. Apply in the planting time and every 6 weeks apart in the entire growing. The fertilizer is ready to use type and does not need a water combination.

Check Price On Amazon

3. Scotts Super Bloom Water Soluble Plant Food

Scotts water-soluble fertilizer is meant to make your lilac flowers bloom in the best conditions. It contains a high level of phosphorus and directly addresses to increase the production of flowering.

Use the fertilizer for outdoor, pots and plants in a container and see the results yourself over time. Re4meber the application of this fertilizer should be every 1 or 2 weeks ahead (preferably 2 regarding the soil type).

The NPK is a 12-55-6 ratio and before you apply make sure the soil is moistened. The amount of nitrogen is 12%, soluble potash is 6% and lastly, the concentration is mostly in phosphate containing 55%. 

Here is how to use it. Fill the watering can and add 2 teaspoons of the fertilizer per gallon. Start from the base and avoid wet foliage and stems. If the soil is dried, water first and then apply the fertilizer. 

Check Price On Amazon

Signs Of Overfertilization in Lilacs

The Lilac flower shows some visible signs when it’s overfertilized. These cases can result with

  • Crusty and tough soil surface.
  • Defoliation.
  • Slow-mo growth or no growth at all.
  • Yellow or brown shade of leaves
  • If you spot some granules in the topsoil, then probably overfertilization is the case.

A Brief Recap

As we have to the end of the article, thankfully this beautiful lilac flower doesn’t need too much care and attention. Before fertilizing, know the soil is ideal when little bit alkaline between 6.5–7.0 pH, moistened, and good drainage.

The very important fact is not to fertilize the lilac plant while the flower, leaves, and stem are wet. Fertilize only the base. In the first year, once a week is ok and the regular fertilization should start in the second.

Further Reading

For other plants, check out a buying guide and how to fertilize azalea. Also here are the frequency and approaches to fertilizing new sod and lastly, you have a full guide on fertilizing arborvitae. You’re welcome.


Aurora Hansen

About Us

FlowerPictures is a website dedicated to the most beautiful things in life - PLANTS!

Its run by enthusiast gardeners that have years of experience.