Fiesta Vs Killex Weed Control

The main difference between Fiesta and Killex is that Fiesta uses an iron-based active ingredient while Killex contains synthetic herbicides. Fiesta is a Selective contact weed killer that dehydrates weeds, while Killex is a systemic weed killer that disrupts plant growth.


Fiesta Vs Killex

This table compares Fiesta and Killex weed control products, highlighting their differences.



Active Ingredients of Ortho Killex is 2,4-D, Mecoprop-P, and Dicamba

Active Ingredients Iron HEDTA (FeHEDTA)

Wipe Out Lawn Weeds Effectively!

You Get Visible Results In 3 Hours

Killex is safe to use around pets and children when used as directed

Fiesta is safe to use around pets and children when used as directed

Mix Ortho Killex of 6 ml per gallon of water to treat 50 square feet

Fiesta Weed Killer has a mixing ratio of 5 oz. Per gallon of water

Simply Mix The Concentrate With Water And Apply With A Hand-held Tank 

Fiesta can be used on lawns, turf, golf courses, parks, playgrounds, cemeteries, and athletic fields.

Ortho Killex is a selective herbicide, meaning it will only kill the weeds that you target.

It's a non-selective herbicide, which means it will kill any plant with which it comes in contact

It can control more than 50 types of lawn weeds includes dandelions, plantain, chickweed, clover, bedstraw, knotweed, ragweed, shepherd's-purse, and more.

Fiesta can kill dandelions, plantains, clover, foxtail, quack grasses, barnyard grasses, curly dock, annual blue grasses, orchard grasses, catch weeds, and many more.


Fiesta Weed Killer is an OMRI-listed, iron-based herbicide concentrate made by Ferti-lome. It is selective, meaning it targets only broadleaf weeds and not grass.

Ortho makes Killex Lawn Weed Killer Concentrate and contains three active synthetic herbicides: 2,4-D, Mecoprop-P, and Dicamba. It is also selective in killing broadleaf weeds without harming lawns.

Visual Results

Regarding the speed of visual results, Fiesta works very quickly, with weed control visible on the same day as the application. Ortho Killex takes a bit longer to show effects, with results in 2 days, but optimal control is reached in 2 weeks.

Active Ingredient

The active ingredient in Fiesta is iron HEDTA, which works by dehydrating weed tissues. Killex contains three active ingredients: 2,4-D, Mecoprop-P, and Dicamba. These synthetic auxins disrupt average plant growth leading to death.

What It Kills

Both weed killers target common broadleaf weeds like dandelions, clover, and plantain. Fiesta can also kill crabgrass and foxtails, while Killex is not effective on grasses.

Neither work on sedges or bentgrass. Killex is effective on a broader range of weeds with over 50 types controlled.

Mixing Ratio

The mixing ratio differs quite a bit between the two weed killers. For concentrated Killex, you mix 6 mL per liter of water to cover 50 square meters. The mixing rate for Fiesta is 5 oz per gallon of water, covering 250 square feet.

Tank Sprayer

Killex and Fiesta can both be applied with a tank sprayer or hose-end sprayer. However, Fiesta is not compatible with hose end sprayers. Use a coarse nozzle tip for best Fiesta coverage.

Pet Safe

An important consideration for weed control is pets. Both Fiesta and Killex are considered safe for use around pets when applied as directed and allowed to dry before pets are allowed in the treated area. Fiesta is non-toxic, while Killex contains synthetic herbicides.

Not Effective

While broad-spectrum, neither weed killer is 100% effective on every weed type. Killex does not control sedges, buttercups, bindweed, bentgrass, or creeping bellflower. Fiesta is also not effective on bentgrass.

Where to Use

Killex can be used on lawns as well as paved areas like patios, walkways, and gravel. Fiesta can be applied to lawns and turf areas like parks, golf courses, and sports fields. Both should not be used in vegetable gardens.


Once dry, Killex is rainproof within 6 hours of application, while Fiesta requires 3 hours to become rainproof. Reapplication may be needed after heavy rains.

When to Apply

The best time to apply either weed killer is when weeds are young and actively growing. For cool-season grasses, early fall is ideal, while spring is best for warm-season grasses. Avoid mowing for a few days before and after application.

How Often to Apply

Depending on the severity of your weed problem, you may need more than one application. Killex states to reapply every 3-4 weeks if needed.

For best results, Fiesta recommends reapplying every 3-4 weeks. Spot treatment may be needed for persistent weeds.

Our Observation
Based on our observation, Fiesta appears to be the better choice for an organic, non-toxic weed control option, while Killex offers more comprehensive weed control with synthetic herbicides.

Fiesta provides effective broadleaf control with faster visual results. However, Killex controls a wider range of weed types and offers longer-lasting effects with its systemic action.

For a natural herbicide option safe for pets, Fiesta would be our top recommendation, but for the most thorough weed control in lawn areas, Killex is likely the superior product. Overall, for broad-spectrum weed control with synthetic ingredients, we would recommend Ortho Killex.

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