Can I combine grub killer with fertilizer?
Written by
Nguyen Minh
Reviewed by
Prof. Martin Thorne, Ph.D.Mixing grub kill with fertilizer requires foresight into the compatibility and timing of the treatment. This was learned the hard way when, in an early part of my career, I injured a client's lawn by mixing incompatible products. Unless the product label specifically says it is permissive to combine, do not. Granular preventative materials usually mix well with fertilizer. Still, for safety's sake and maximum effectiveness, it is better to apply liquid curatives separately.
Product Compatibility
- Check labels for explicit combination instructions
- Granular preventatives like GrubEx® blend with slow-release fertilizers
- Avoid mixing liquid curatives with any fertilizers
- Natural treatments combine with organic fertilizers only
Application Timing
- Spring applications: Combine preventatives with balanced fertilizers
- Fall applications: Apply fertilizers 2 weeks after curative treatments
- Never combine during drought or heat stress
- Apply at dawn/dusk to minimize pollinator exposure
Safety Protocols
- Prioritize bee-safe ingredients like chlorantraniliprole
- Water immediately with 0.5 inches irrigation
- Keep pets off until completely dry
- Store unused mixtures in original containers
Apply the spring combo with the calibrated broadcast spreader to ensure even coverage. I use the 50/50 method, applying half north-south, half east-west. Water immediately using 0.5 inches of irrigation to activate both products. Avoid windy days to minimize drift onto ornamentals.
Protect pollinators by choosing combinations using only products containing chlorantraniliprole. These kill grubs without harming the bees that are attracted to the flowers in clover. I exclusively use these in my lawns adjacent to my apiaries. Always mow before application, thereby removing the flowering weeds, which are beneficial attractants for insects.
Keep treatment records, combining them with results achieved. Keep records of all recovery responses and harmful reactions received. My log book shows a uniform success in securing prevention through the use of the granular form united with a fertilizer of 20-5-10. Liquid combinations were adopted, resulting in a spotty finish, and reapplications became necessary.
Be aware of symptoms of incompatibility, including fertilizer burn or lack of effect. Yellowing grass tips are indicative of chemical conflict. If damage occurs, immediately stop using the application. Flush the area with excess water and contact the manufacturers of the products used. Preventing problems is more effective than trying to correct them after they occur.
Read the full article: Effective Lawn Grub Treatment Guide
