Fertilizing Phlox

When planting phlox add a balanced 10-10-10 fertilizer blend or compost to the backfill soil. Fertilize annually with compost or a balanced slow-release granular formulated fertilizer when flower buds begin forming. Lightly fertilize after the flowers fade, and the phlox may rebloom. Perennial phlox should grow a little wider every year.


How To Fertilize Phlox

Always follow the directions on the fertilizer package to avoid over-fertilizing. Over-fertilizing is often more detrimental than under-fertilizing. Over-fertilizing is likely to burn the plant’s roots resulting in death. Avoid getting fertilizer on the plant stem and leaves unless it is formulated as a foliar feed. 

Always water after applying granular or powder-based fertilizers. Wear a mask when using powder fertilizers, and don’t fertilize on windy days. Carefully measure when diluting a concentrated liquid fertilizer. Stop applying fertilizer if your plant becomes leggy.

Best Time To Fertilize Phlox

The best time to fertilize an established phlox plant is when flower buds form. This may range in time from mid-spring to mid-summer depending on the variety. Spreading phlox varieties tend to bloom earlier than tall cultivars. Fertilizing phlox once a year is adequate. Applying a second dose of fertilizer after the blossoms die may result in a second flush of flowers.


Best Fertilizer For Phlox

Phlox will benefit most from a balanced fertilizer blend like 10-10-10 or similar. Top dressing with compost can be done instead of applying fertilizer with good results too. It’s more convenient and easier to use granular fertilizers on garden plants and liquid fertilizers on container-grown plants.

Phlox Fertilizing Tips

  • · Wear gloves when handling fertilizer.
  • · Always follow the directions and precautions listed on the package.
  • · Store fertilizers in their original packaging to retain the instructions.
  • · Water after applying powder or granular fertilizers.
  • · Do not apply powder fertilizers on windy days.


-Always wear protective gloves and a face mask when handling chemical fertilizers.

-Closely follow all directions and storage guidelines that are on the fertilizer label.

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 Author Maureen Farmer - Published 02-22-2022