2, 4-D, (2,4-Dichlorophenoxyacetic acid) is a selective herbicide that controls and kills a wide range of broadleaf weeds. 2,4-D is often combined as a 2-way, 3-way, or 4-way herbicide, generally mixed with dicamba, MCPP, triclopyr, MCPA, MCPP, or Carfentrazone. When trying to eradicate weeds, you’ll probably wonder how long does it take for 2,4-d to kill weeds…
How long does 2,4-d take to work?
2,4-d takes about 7-14 days to kill weeds. Visible evidence can be seen as early as the first 48 hours after application – under ideal conditions and when applied according to the label instructions. Signs of dying include weeds wilting and discoloration (brown, yellow, orange).
Under ideal conditions and when applied according to the labeled instructions, 2,4-D will begin to show visible evidence on broadleaf weeds as early as the first 48 hours after application on labeled weeds.
The plant or weed should be dead in about 7-14 days. If needed, a second round of 2,4-d can be applied 2-3 weeks after the first application (21-30 days). We found it very effective against horseweed.
What is 2,4d?
Dimethylamine salt of 2,4-Dichlorophenoxyacetic acid (2,4-d) is a selective herbicide and broadleaf weed killer originally made by Dow AgroSciences
2,4-d will control weeds post emergently but is not a pre-emergent herbicide.
Popular broadleaf weed killers are “3-way herbicides” which means they contain three Active Ingredients (3 AI). Traditionally they combine 2,4-D, Dicamba, and MCPP. My favorite 3-way herbicide is EndRun.
SpeedZone, one of the best-selling selective herbicides on the market, is a 4-way herbicide. This is a “3-way” with the addition carfentrazone (4 AI).
Lastly, OnDeck is a 2-way herbicide that contains 2,4-D and Dicamba (2 AI) (read more Lawn Care Acronyms).
How to use 2,4-d
Always refer to the manufactures label before applying any weed killers, including 2,4-d.
- Fill sprayer with half the amount of total desired application
- Add enough herbicide, 2,4-d and non-ionic surfactant for measured area to the tank/backpack sprayer
- Fill the tank with the remaining half of water
- Mix/agitate to ensure the chemicals are evenly dispersed and suspended
- Spray actively growing weeds according to the labels
Some other useful tips
- Do not spray on stressed turf – this includes grass that is under heat, drought, fungus, or insect damage or stress
- Do not spray when outside temperatures are over 85 degrees
- Do not apply to a wet lawn or damp weeds
- Use an adjuvant such as a non-ionic surfactant for the 2,4-d to better stick to the weeds
- Weeds tend to turn color and wilt in 1-2 days after application
- Kills plants usually in two applications (between 10-14 days)
- Do not spray on newly seeded grass for at least 6 weeks post germination
- Do not apply less than 4 weeks before seeding or overseeding
Selective Weed Killer
2,4-d is a selective weed killer – meaning it will only kill the grasses and weeds that are labeled. For example, when applied according to the instructions, it will kill broadleaf weeds such as clover and other perennial weeds, but will not harm most grasses.
The opposite is a non-selective herbicide – such as glyphosate – which will kill everything it comes in contact with.
Our recommended broadleaf weed killers with 2,4-d:
Labeled Broadleaf Weeds
2,4-d Herbicide FAQs
How long before 2,4-d is rainfast?
The rainfast timing for 2,4-d is 4-6 hours after the application has dried. Some herbicides such as TZone – which also contains Dicamba, Sulfentrazone, Triclopyr – are rainfast in three hours after the application has dried, so always refer to the product and manufacturer labels.
How long after you spray 2,4-D Can you mow?
Like most weed killers, do not mow two days before or two days after (72 hours) a 2,4-d application. For example, mow on Monday, spray 2,4-d on Thursday, and mow again on Sunday.
How long does 2,4-D need to be on before rain?
2,4-d and most selective herbicides should allow to dry and penetrate the plant 4-6 hours before rainfall or irrigation.
How long after you spray 2,4-D can you water?
Always check the manufacturer’s labels. But in general: If dry conditions exist, you should irrigate 24 hours after applying 2,4-d. Otherwise, wait 4-6 hours after applying 2,4-d.
Can 2,4-D be mixed with other weed killers?
Yes, 2,4-d is generally mixed as a 3-way or 4-way herbicide – meaning it is one of 3 or 4 Active Ingredients (AI). Products that contain 2,4-d like SpeedZone and TZone can be mixed with Tenacity herbicide (mesotrione) and Drive XLR8 (quinclorac) respectively, to kill broadleaf weeds and grassy weeds including crabgrass.
2,4-d is an organic compound – which is a chemical compound that has carbon in its chemical structure.