Here’s How Often You Should Spray Scale (And What To Use)

Complete guide on using scale spray

Scale can affect many types of plants, and can be difficult to remove due to their short lives and multiple reproduction cycles per season. These insects are best sprayed for when they are young, during the part of their life cycle where they are mobile and haven’t yet formed their hard outer shells, which sometimes lasts only a few days!

Scale is easily treatable with natural remedies, including neem oil, isopropyl alcohol, dish soap, physical removal, and a combination of treatments. Because generations often overlap, you should continue treating scale with spray every couple of weeks.

Scale can be stubborn little creatures that are hard to completely eradicate, even with the best technologies, so keep reading to discover how, when, and how often you should spray scale.

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When And How Should You Spray For Scale?

Before we get into what treatments are effective for removing the scale, we should discuss when is the best time to remove them and how to apply sprays and other techniques.

Large infestations of scale can be very hard to remediate completely because scale can produce multiple generations in a single season. 

Knowing when and how will help to make your remediation methods work faster and more effectively. 

1. Start An Initial Spray Immediately When You Spot Them

You should begin remediation as soon as you recognize scale has made a home on your plants, and remember – scale can affect both indoor and outdoor plants!

There are two main varieties of scale: armored, and soft-bodied.

Armored scales are much more common in houseplants and produce multiple generations per season. 

Adult Scale

The University of California describes adult and immature scale as oval-shaped, wingless insects that do not have distinct body parts or separation between the head and body. 

Adult scales are also immobile, attaching themselves to a single place on your plant’s foliage. Females lay eggs where they are attached, and keep them underneath their bodies to protect them. 

Make sure you have correctly identified scale before you begin to treat your plants because other pests can be mistaken for scale such as aphids, mealybugs, and whitefly nymphs. 

And we mean it! Scale can be mistaken for mealybugs, head on over to our article about plants mealybugs love, if not for anything, but to see how easily confused they can be with scale!

2. Make Your First Spray Thorough

Don’t hold back when applying treatments to scale, making sure to thoroughly cover the infested leaves and branches with whatever spray you are using.

As well as being thorough, the University of California Integrated Pest Management advises that you should also make sure to wet the entirety of the infested branches, especially including the undersides of leaves and the terminals where leaves branch off. 

Scale have a waxy or armored coating on their bodies, so a thorough spray is essential to ensure that you are covering the scale enough to penetrate this outer layer and get rid of them for good!

3. Re-Apply Spray Every Two Weeks If Your Plant Is Still Affected

According to the University of South Dakota, after a thorough initial application, you should continue to treat scale at least every 2-5 weeks! This is due to the short life cycle of scale and the overlapping of generations that can occur. 

Treatment will be most effective on scale that are in the younger phase of their life cycle.

Additionally, warmer temperatures in indoor plant environments or greenhouses have been found to accelerate the rate of reproduction and life cycle. 

Scale is often found in large numbers of varying ages, and scale will reproduce at different times, and the thing is – these little insects are hard to get rid of because of this! Check out our other article about scale and how to get rid of them, for more in-depth tips following this article!

4. Avoid Spraying When It Is Too Hot

The best time to begin spraying is right after scale comes out of winter dormancy, when they are most active, and during the first reproduction cycle.

This will occur from late winter through spring, as temperatures begin to thaw and pests emerge and begin to reproduce. 

Part of this is due to the vulnerability of young scale, but part of it is to protect your plant during the hottest part of summer. 

Too Hot Temps Can Cause Harm To Plants!

Many horticultural sprays, soaps, and oils can actually be harmful to plants if applied when the temperatures are high and the sun’s rays are most intense and can dehydrate the plant!

In addition to dehydration, many of these products have ingredients that are photosensitive and can cause burns or injury to the plants when exposed to the sun. 

For these reasons, try to avoid spraying when temperatures rise about 85-90 degrees Fahrenheit, especially during drought or when plants are water stressed already, as corroborated by Clemson University. 

5. Spray When The Scale Are Young

The juvenile phase of the scale’s life cycle, otherwise known as “crawlers,” is when the creatures are most vulnerable to spray or other treatment methods.

This is because the scale have yet to form their hard outer shells, which protect them from most treatment methods. 

Keep a close eye on the scale to try to establish a base knowledge of when and how often they are reproducing.

By keeping track of their life cycles, you can pinpoint when these crawlers are most likely to be active and treat the plants then

What Are Some Natural Methods Of Removing Scale?

Macro Photography of Scale Insect - Coccidae on Green Leaf

While large infestations of scale can be difficult to remove, the pests are actually quite vulnerable to many natural removal methods.

Especially when treating indoor plants or food crops, you should opt for more natural remedies. 

Luckily, there are many options for treatment that have been proven very effective in removing scale. Read on to discover some safe and effective treatment options. 

Neem Oil Spray Can Be Simple And Effective

One of the simplest and most effective ways to remove scale is by using a neem oil spray such as this one from Natria Neem Oil that is specially formulated for indoor plants.

Neem oil works by coating the scale in oil and will act as an insecticide.

In addition to treating scale, neem oil will also get to work on other pests and mites as well as acting as a fungicide.

Neem oil will degrade after a few good waterings, so make sure to apply it often as the infestation persists. The best part is, neem oil is inexpensive and incredibly easy to find at garden stores or online, check out

Physically Removing Scale Can Work Well

Another remedy for scale is simply physically removing them. While scale affix themselves to the leaf when they mature, they are actually not very strong and can be removed with just a tiny amount of force. 

The University of Maryland recommends using your fingernail, a toothpick, or a toothbrush to gently remove the scale from the leaves and stems. 

Physical removal is a great way to ensure that you are reducing the number of scale that are on the plant, preventing them from reproducing and making it easier to recognize when their numbers begin to grow again. 

Even after you physically remove the scale, you should still treat the plant with neem oil or other methods. Physical removal will reduce the population size, but you are unlikely to get to all of them using this method, warranting continued treatment. 

Isopropyl Alcohol Works Great On Adults and Crawlers

Rubbing alcohol is another commonly used method of removing scale.

For this method, soak a cotton swab in isopropyl alcohol and gently rub the adult scale on infested leaves and branches. 

Continue to treat the small yellow spots left behind where the adults were, as these are most likely eggs or crawlers which have not yet emerged from underneath the mother scale. 

The concentration of isopropyl alcohol does not seem to matter, according to the University of South Dakota, and you can use any drugstore version!

Dish Soap Can Help 

Unscented and dye-free dish soap like this one from 365 Whole Foods Dish Soap can be an effective treatment for scale. Try diluting the soap in a spray bottle with water and saturate the leaves and affected areas. 

Dish soap contains glycerin and other plant oils that act in much the same way that neem oil does by suffocating the scale. 

Be careful to use soaps without fragrance or dyes, because these additives can cause damage to the foliage or interact with sunlight, burning or otherwise injuring the plant. 

Try A Natural Pest Removing Spray

If you already have a few of these products on hand, you can easily create a DIY mixture that will be extremely effective on scale.

To create this mixture, combine a small amount of dish soap, neem oil, and a one-to-one ratio of isopropyl alcohol and water in a clean spray bottle. 

This mixture creates the perfect combination to get the adults to release their grip on the plant and become coated in oils, while the soap helps to spread the product over the entire area.

If you are not inclined to DIY a solution, there are many natural pest sprays you can purchase premade, such as Earth Ally Insect Control.

Remove Leaves That Are Overrun By Scale

If you have an infestation that has gotten out of control, and there is already significant damage to the foliage including yellowed, wilting, or brown leaves, it is best to simply remove the worst of the leaves.

Scale is mobile during the crawler phase of its life, and there is a high chance that an overrun plant will transfer the pests to other plants you may have nearby.

Use these Vivosun Gardening Scissors to snip off affected leaves and dispose of them by bagging them and taking them to a closed trash receptacle outside, where they have less of a chance of transferring to other plants on their way out.

How Can You Prevent Scale From Getting On Your Plants?

Macro Photography of Scale Insect - Coccidae on Green Leaf

Speaking of spreading, if you have noticed a scale infestation in one or more of your plants, definitely take steps to prevent the scale from spreading to more plants.

The reality is, there are numerous ways to control and prevent scale from spreading – so, don’t fret just yet! Following these few tips, make sure to check out our in-depth article about why scale spread to other plants, and what you can do about it!

Isolate Affected Plants When Possible

If at all possible, you should take steps to isolate the affected plants during treatment. Move the affected plants to another room or at the very least, put several feet of space between them and the healthy plants.

You may even want to turn off nearby fans or your air conditioning, because crawlers do move from plant to plant on foot, but can also be transferred by the wind. 

Scale can also be transferred by people, attaching themselves to your clothing or gloves.

Be extra careful to use clean gloves and inspect your sleeves and the rest of your clothing carefully when moving between affected and healthy plants, and if you are unsure about removing the scale, we suggest contacting a local professional to assist you.

Isolate New Plants

When bringing home new plants from the nursery, you should isolate them before introducing them to the rest of your plant collection at home.

Place the new plants away from others in another room such as the bathroom or even outside. 

It can take time to notice an infestation, so keeping new additions isolated will prevent any issues including scale from spreading before you notice and treat them. 

Use Tape Traps To Capture Crawlers

Trapping crawlers while they are mobile is a good method to keep the juveniles from spreading throughout the plant or from finding new hosts on other plants.

Tape traps are sticky on one or both sides, and as their name suggests, capture small insects. 

Set up Hedoc Yellow Sticky Traps around affected plants, even using strips to encircle twigs and branches.

Wash Pots Before You Reuse Them

Washing new and old pots before repotting plants is an important step to prevent the transfer of scale and other pests.

Many of this scale can remain dormant for long periods of time, especially over the winter season. 

So, before you start your spring repotting project, give your pots a thorough wash to remove any critters that may be hiding in cracks and crevices, waiting for a new host plant to attack. 

Clean Repotted Plants And Their Roots With Hydrogen Peroxide

If you are repotting a badly affected plant, you should give the whole plant a cleaning using diluted hydrogen peroxide to remove any residual eggs as well as other fungi and pests that might be attacking the plant. 

Plants become more vulnerable when dealing with an infestation of scale, which eats away at the foliage and the nutrients within.

Hydrogen peroxide will take care of any bacteria or fungi while helping the plant to absorb more oxygen through the roots. 

This method will help to recover more quickly from a pest infestation while eliminating new scale and pests.

Let Plants Have Plenty Of Air And Light Circulation

Another good practice to maintain healthy, pest-free plants is to make sure your plants are getting plenty of light in an area with good ventilation. 

Pests such as scale thrive in moist, dark environments, crowding the dark inner parts of the plants near the stem.

Avoid contributing to this environment by keeping plants in a well-lit, well-ventilated area of the house. 

Regularly Check Your Plants For Scale

The final tip I will leave you with is simply to check on your plants thoroughly and often.

Scale will begin to emerge in early spring and will continue to reproduce throughout the summer.

Treatment is most effective early on in the life cycle of the scale, so it is important that you are catching infestations early to make it easier to treat as time goes on. 

Quick Recap! 

Hopefully, by now, you feel well-equipped to treat scale in your indoor plants or garden. Even though pest infestations can feel scary, there are many easy, natural methods to remove scale for good and keep them from returning. 

To recap what we learned, the best methods to remove scale are: 

  • Neem oil 
  • Physical removal using your fingernail, a toothpick, or a toothbrush
  • Isopropyl alcohol 
  • Dish soap
  • A DIY mixture or store-bought natural insect spray
  • Pruning affected leaves

Finally, try to treat the scale when they are young crawlers, and keep applying the treatment until they are all completely gone because they will continue to reproduce many generations in one season. Thanks for reading and good luck! 

References: 

  1. Nile, A.S., Kwon, Y.D. & Nile, S.H. (2019) Horticultural oils: possible alternatives to chemical pesticides and insecticides. Environ Sci Pollut Res 26, 21127–21139.
  2. Ogbuewu, I.P., et. al. (2011) The Growing Importance of Neem (Azadirachta indica A. Juss) in Agriculture, Industry, Medicine, and Environment: A Review. Research Journal of Medicinal Plant 5(3): 230-245. 
  3. Johnson, P.J. (2008) Scale Insects on Orchids. Insect Research Collection. South Dakota State University. 
  4. Bhise, K., et. al. (2018) Plant Virus: A Brief Review. International Journal for Research in Applied Science & Engineering Technology. 6(9): 147-149. 

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