The Difference Between Mold & Mildew

empty room in a new apartment with wooden floors and white walls and a serious mildew and mold problem

Have you ever walked into a home only to be hit by a strong musty smell that nearly sent you reeling backward out the door? Have you ever left a load of laundry in the washer for a few hours only to have them come out smelling like they’ve been in a swamp after they’ve gone through the dryer? These are telltale odors of mold and mildew.

It’s easy to confuse mold and mildew, and many use the terms interchangeably. While they are both types of fungi, there is a stark difference between the two. Here, we’ll discuss the differences between mold and mildew, how to spot them, their effects and how you can be rid of them for good.

Mold Types

You might be saying, ” Mold is mold.” However, there are several species of mold with various origins, appearances and effects. The following are more common types you might encounter.


This plant-based mold spore causes human allergies. It grows on plant leaves and spores become airborne, which causes hay fever and can even lead to asthma.


There are about 180 species of aspergillus, and most of them aren’t harmful to humans. This mold species thrives in soil, on plants and in air vents. While it’s not typically dangerous to healthy people, it can make anyone with a weakened immune system, allergies or lung diseases sick and cause Aspergillosis.


Some people can develop allergies and asthma when they’re exposed to this mold. It grows indoors and outdoors. You can find it on living and dead plants.

Stachybotrys Chartarum

This type of mold is known as black mold or toxic mold. If you live in a home where this type of mold grows, you’ll need to perform a search and destroy it immediately. This mold is dangerous and can lead to serious health complications, including death.


Imagine coming home to find a black spot growing in the corner just below the ceiling. You ignore it thinking it’s nothing, until one day, it’s the size of a golf ball. Upon closer inspection, you find it’s fuzzy and giving off a musty odor. Suddenly you realize, it’s mold!

Mold is an eyesore. It is green, blue, or black in color and has a fuzzy or slimy texture. When it grows on organic material, mold is typically green and powdery. But, when it grows on walls and in damp or moist areas, it appears black or green and slimy. As its water source dries up, it becomes black and powdery. When mold isn’t visible, you may still detect it by the telltale musty odor it produces.


Mold grows underneath wet surfaces indoors and outdoors. It prefers dark, damp areas, but can grow just about anywhere water can touch. For example, you can find aspergillus in compost piles, on decaying vegetables, and in grain. Outdoor spaces that remain wet are likely to harbor mold spores and allow mold to flourish. Certain types of mold prefer specific environments, while others can grow almost any place with the right conditions. Some types of aspergillus grows on fruit and vegetables, such as oranges, strawberries and cucumbers. You can even find it on fruits and vegetables forgotten in produce bags in the refrigerator.

Where It Grows

Mold grows where leaks are present in homes, like around windows, pipes, and under roofs. If your bathroom has flooded or a pipe burst in your kitchen, the area may have developed mold. These conditions are extremely hospitable to black mold.

Mold can appear as spots on walls where moisture is constant. It develops in the dark, damp space behind the wall, and as it grows, the spores snake their way through drywall and present as tiny spots, which will grow in size. It can also grow on paper, in dust, cardboard, carpet, and upholstery. If it can get wet, it can grow mold. Not only that, but mold spores become airborne and can lead to a whole host of other problems.


Mold can cause serious damage to structures when left untreated. It feeds on wet wood and seeps into porous surfaces. When it grows in the walls, it destroys wood and drywall, causing them to break down and compromise structural integrity. In severe cases, it can cause roofs and floors to collapse. Untreated mold can result in buildings being deemed up uninhabitable and condemned.

Aerosolized mold spores get into your ventilation system and take a negative toll on household members’ health. People in the house breathe in the spores, and respiratory issues, such as asthma and mold-specific conditions like Aspergillosis, begin. People who have underlying health conditions can suffer detrimental health conditions such as pneumonia and recurring lung infections.

How Difficult is Mold to Remove?

It’s easier to rid your hard surfaces of mold than porous or cloth and fabric surfaces. Tile and grout are easy to clean. The four primary cleaners that can get rid of mold are:

  • Soap
  • Water
  • Bleach
  • Ammonia

Before you tackle mold removal, remember to never combine ammonia and bleach. In fact, it’s better to store them in separate places to limit the chances they come into contact with each other. The combination will cause toxic fumes, which can be deadly in areas with poor ventilation.

Protect your skin and eyes with rubber gloves and plastic goggles when cleaning up mold. Combine soap and water to clean mold from hard surfaces. Soap and water won’t kill remaining mold spores, but it’s a start. To kill remnant spores, you’ll want to use bleach or ammonia. Dilute one cup of bleach in one gallon of water and spray the affected area. For ammonia, use a 50/50 solution of water and ammonia and spray the area. Ammonia isn’t as fast-acting as bleach, so you’ll want to let it sit for about 5 to 10 minutes before scrubbing away the offending fungus.

Black mold can only be removed by professionals. It requires specialized equipment and safety precautions homeowners don’t generally have access to.

Mold infestation can get out of hand. At that point, you need a professional to eliminate the mold for good. They will use specialized equipment and protective gear to permanently remove the mold.

However, after you’ve removed the mold, you have to be vigilant to prevent it from returning.

How to Prevent Mold

Mold is a preventable household problem. The best way to keep it out of your home is to ensure wet areas, like the kitchen and bathrooms, stay dry. A bathroom exhaust fan can help. However, this can be tricky in more humid areas or locations where humidity and moisture are the norm.

A dehumidifier can help bring down the humidity in your home. Humidity levels should be below 50% indoors. When cleaning in damp areas, you should use mold-killing products, like bleach or ammonia, and allow the area to completely dry. Should a room in your home flood, be sure to dry the space as soon as possible. Remove baseboards and pull up carpeting to prevent mold from taking root. Portable floor fans and dehumidifiers work miracles for mold prevention after a flood.

If you paint your home, you can add a mold inhibitor to decrease the chances of mold growth. You can usually buy mold inhibitors wherever you buy paint.


Mildew is a type of mold, but unlike its cousin, it doesn’t invade and wreak havoc on building structures. It can, however, effect farmers and crop growers if left to its own devices.

Powdery Mildew

Powdery mildew is a plant disease sapping plants of nutrients. It thrives in warm, dry areas and doesn’t require much moisture or humidity. It’s caused by a fungus similar to mold. If you’ve ever noticed powdery white spots on your houseplant with dead spots soon after, you can blame powdery mildew.

Downy Mildew

Despite the name, downy mildew is not a true fungus. It’s a plant parasite, which destroys crops like kale, grapes, and vegetables. It does not grow in home environments, as it prefers warm, dry environments like gardens in the springtime.


Mildew is white, grey, or sometimes yellow in color and has a fluffy or powdery texture. It usually appears on plants and vegetables, but it can grow on paper, cardboard and other organic materials.


Unlike mold, which requires cool, damp environments, mildew thrives elsewhere — warm, dry climates. If the environment is usually wet, the culprit is probably mold.

Where It Grows

Powdery mildew grows on a wide range of fruits, vegetables, and plants in warm, dry climates. It’s unlikely to grow on indoor surfaces unless it’s a houseplant.


Mildew destroys flowering plants and vegetation. It can decimate crops and lead to poor production seasons for farmers as it saps them of nutrition.

Inhaling mildew spores can cause sinus congestion, watery eyes, throat irritation, and headaches. The effects are usually less severe than those of mold due to mildew remaining mostly outdoors.

How Difficult is Mildew to Remove?

If you suspect mildew is growing on surfaces in your home, you can use a solution of vinegar and water to remove it. Don’t spray vinegar on plants, as the acidity can kill them.

To remove powdery mildew from your houseplants, you can spray milk or a solution of milk and water directly on plants. To prevent it on plants, spray them with a solution of baking soda, liquid soap, and water.

Testing for Mold

There are a few methods for testing mold in your home:

  • Air sample
  • Surface sample
  • Bulk sample

An air test collects samples from the air in strategic places in your home. Then, a professional examines the sample under a microscope to determine if mold is present or pervasive in the area. This can help when you don’t see evidence of mold.

A surface test requires a swab of an affected surface, such as a shower or countertop. You can do this with a cotton swab or lifting a sample with tape.

For a bulk sample, a tester cuts off a piece of the sample area (a countertop, a slab of drywall, etc.) and carts it off to a laboratory for testing.

Professional Testing

When it’s behind walls or in air vents, it can be hard to detect if there’s a mold issue. Professional testing can help you learn if it’s in your home and pinpoint its location by perfomring a mold test via air, surface or bulk sampling. The service you use will determine the best method. They send the samples off to the label and can usually deliver results in 24 hours.

Home Testing

If cost is a concern, there are home test kits on the market for DIY mold testing. Although these don’t compare to professional inspection, they can give you an indication of whether you have a mold problem. It’s good to remember most in-home mold tests will show positive results because most houses, especially older ones, show signs of mold, even when there’s no infestation.

A home test kit utilizes a Petri dish and a growth medium. The homeowner prepares the Petri dish and sets it in an area where it can collect a sample of falling debris. Any airborne mold spores fall onto the Petri dish and mold forms. Collection can take an extended amount of time.


You can tell mold from mildew by their colors and their locations. And while in many forums the terms are used interchangeably, they are two distinct types of fungi.

If you find fuzzy, black spots growing on your walls or in the corners of your shower tile and grout, more than likely, it’s mold. If you see something white and powdery on your house plants, it’s probably mildew. Mildew is typically white or grey and occasionally yellow. Mold is green, blue and black. While mold and mildew are different types of fungi, each can have negative effects on their environments and the people living in them.

Mildew can be a nuisance. Mold can be deadly. If you suspect you have mold in your house, you need to locate and eradicate it immediately. Cleaning products, dehumidifiers, and different types of fans can help maintain your home and get rid of mildew and mold.

Your physical health and the health of your home could be at stake. If the mold problem is too large to tackle on your own, it’s best to hire a professional and ensure it’s done right.


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