Fertilizing Beardtongue

Beardtongue plants are not heavy feeders, but they still benefit from some nutritional assistance. Depending on the cultivar, these flowering perennials can grow very tall and large, without needing rich soil or fertilizer to reach their full potential. Too much fertilizer can actually cause lanky and floppy growth. Similarly, manure is too rich for penstemon and should not be added to the soil. If you choose to feed Beardtongue, only fertilize lightly once a year with a formula low in nitrogen and higher in potash to support blooming. Older plants and long bloomers may benefit the most from a light feeding. 


How to Fertilize Beardtongue

These plants naturally grow in sandy conditions without many nutrients, so they are accustomed to poor soil quality. When feeding Beardtongue, choose a slow-release formula without excess nitrogen to support the roots and bloom cycle. Test the soil prior to feeding, as many garden soils are rich enough to support Beardtongue without any supplements. Neutral to acidic soil is ideal for Beardtongue, so be sure to test the pH level as well.  

Water the plant when applying fertilizer so the roots can absorb the nutrients. Saturating the ground before applying fertilizer also prevents fertilizer burn.

Best Time To Fertilize Beardtongue

Amend the soil with organic compost and pumice when planting to support growth for the first growing season and improve drainage. Fertilize Beardtongue once each year. The best time of year to fertilize Beardtongue is in the fall. Cap off the growing season by fertilizing the plant to help it prepare for the following spring. Feeding Beardtongue in the spring can have a reverse impact and cause too much growth. These plants are not heavy feeders, and fertilizing in the spring can promote too much growth too quickly, causing the plant to fade part way through the growing season. Fertilizing Beardtongue in the fall allows the plant to make better use of the nutrients when new growth emerges in the spring. 


Best Fertilizer For Beardtongue

Feed Beardtongue using organic fertilizer that is low in nitrogen. A plant food with a ratio of 5-10-10 or something similar will be best for Beardtongue. Use a slow-release fertilizer so the nutrients can slowly be absorbed into the roots.

Beardtongue Fertilizing Tips

  • Do not fertilize newly planted Beardtongue 
  • Use a slow-release granular fertilizer low in nitrogen
  • Apply fertilizer once per year in the fall
  • Water thoroughly to help dissolve the fertilizer


-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.


 Alison Cotsonas Profile Pic

Author Alison Cotsonas - Published 05-03-2023