How Long Does It Take For Ammonia to Kill Grass?

Many home products can have multiple uses, some of which are not necessarily recommended by the manufacturers. Common household ammonia or ammonia hydroxide is one of those solutions that can serve many purposes and help keep things clean around the home.

Other types of ammonia, like ammonium phosphate sulfate and ammonium sulfate, can even have lawn and garden applications.

When used in the lawn, ammonia can either help or hinder our turf. It is important to always consider the type of ammonia, the amount you will use, and the maturity of your lawn before attempting to use ammonia for grass improvement.

Likewise, you can consider using ammonia for weed control and other practical pest solutions; read on to find out if ammonia will kill grass and what to do to prevent ammonium toxicity. 

Will Ammonia Kill Grass?

Common ammonia found in homes, like ammonium hydroxide, will kill grass on contact and can kill soil microbes and harm aquatic wildlife. Damage ammonia causes are relative to the concentration and exposure time the grass has with the solution.

Other forms of ammonia, like ammonium sulfate, ammonium nitrate, and ammonia phosphate, can improve your turf or condition the soil to make your lawn more suitable for acidic soil-loving plants and will not kill grass if used correctly. 

Should I Spray Ammonia on My Grass to Fertilize it?

Only ammonium nitrate or ammonium phosphate sulfate should be sprayed or applied as crystals with ammonium to fertilize lawns. Ammonium sulfate and the common form of ammonia found in homes should not be used as a fertilizer and never be sprayed directly on grass unless you want to kill it or make the soil more acidic.

Ammonium sulfate effects are more subtle than household ammonia which will burn the turf immediately and lead to quick irreversible death. 

Are there Different Types of Ammonia?

Whether you want to nourish your grass or kill it, there is a type of ammonia for you. While it is better to get an appropriately formulated commercial herbicide or ammonium nitrate fertilizers, it is possible to treat your yard with common types of ammonia found around your home.

Every kind of ammonia will have a different effect and can act as a grass killer to eliminate common weeds or add a pound of nitrogen for rapid plant growth. Below are the most common types of ammonia and what they are for. 

Ammonium Nitrate

Used as a common fertilizer in home and agricultural plant feeding, it only takes about 3 pounds of ammonium nitrate to provide 1 pound of plant-ready nitrogen per 1000 square feet of soil. It is important to only use this fertilizer on mature lawns as young lawns that lack advanced photosynthetic abilities may not be able to handle the influx of nitrogen effectively. 

Ammonium Phosphate Sulfate

The most gentle form of ammonia, it can be added to younger lawns and is absorbed slowly and efficiently. it takes 5 lbs of ammonium phosphate to produce 1 lb of nitrogen per 1000 sqft, but the chances for ammonium phosphate to burn your turf are far lower than with ammonium nitrate. 

Ammonium Sulfate

This is used to make the soil more acidic to help plants like blueberries or azaleas thrive. A powder form of ammonium sulfate can be mixed into topsoil when you are preparing to plant something that likes a lower pH of 5.5 or so. Make sure to add carefully, as pH adjustments can be exponential and quickly kill plants instead of helping them. 

Ammonium Hydroxide

Household Ammonia is used for cleaning and sterilizing. Ammonia is always diluted, and the amount of dilution or specific concentration of ammonia changes depending on the brand. It is unwise to use this as a lawn fertilizer since knowing the exact ratio of water and ammonia is difficult, but it can be used as a weed killer if no better option exists or an immediate solution is needed. 

Uses for Ammonia

Ammonia, in its common form, can be used for several things. Though it is not advisable to use it for fertilizer or kill weeds, household ammonia can be used for these things if diluted with enough water and applied correctly.

Make sure to try the fertilizer mix on a small area of the lawn first to avoid big losses, and always apply weed killer when the weather is calm and not too sunny. Below are some formulas for effective ammonia solutions. 

Use	Formulation	Application
Cleaner	10 parts water 1 part ammonia	Place in a bucket and use a cloth (wear gloves) or mop to clean and sterilize surfaces around your home
Fertilizer	100 parts water 1 part ammonia	Place a tiny amount of ammonia in a sprayer with at least a gallon of water and spray gingerly throughout your lawn during the active growth season
Weed Killer	2 parts water 1 part ammonia	Spray directly on the foliage of the target weed and avoid spraying on windy days

Does Ammonia Kill Weeds?

Ammonium hydroxide can kill weeds, although it is not a good solution for annual lawn weed removal. The goal of ammonia is to clean and remove grease and tough stains, and the same chemicals that work for that will burn plants to the root.

It will kill lawn weeds fast but will also bioaccumulate and harm wildlife. Some herbicides with ammonia contain trace amounts of this chemical, but not too many use it as the main active ingredient due to its toxicity. 

What to Do If Ammonia Gets on Lawns?

The best thing to do if ammonia spills on the lawn are to water it deeply. Ammonia will break down naturally, but the more it is diluted, the less negative impact it will have, and the soon the lawn can start to recover. The longer ammonia spills sit on the lawn, the more it will seep into the soil and kill, so act quickly to reduce damage.

Pick up and set safely out of the way the container of ammonia that has spilled. Use a hose or other large-volume water source to flush the area without spreading the ammonia around too much.

Try to keep the spill localized and let the water run until there is no odor or frothiness. Monitor the area for several days to make sure the turf recovers. If brown spots appear, then remove the dead grass and re-sod or sow. 

Make sure to flush again if replanting seeds to make sure all the ammonia is gone and there are no residual chemicals to prevent seed growth. Grass that ammonia kills will die quickly within 24 hours, so make sure to do your best to clean and flush spills right away.