How Long Does It Take for Mold to Grow? It Depends!


Does a leak or humidity have you worried about mold growing in the home?

Don’t sweat it! You’ve come to the right place to get this issue fixed.

Mold takes between 24 and 48 hours to grow after the water has been left on a surface. This can quickly become a larger mold problem within a couple of weeks – depending on whether the conditions remain right for mold to grow. Mold spores are usually visible after 18-24 days.

Luckily, in this article, you’ll learn how to prevent mold from growing to keep your family and home safe. Moreover, you’ll also learn how to clean mold patches.

Keep reading to learn more about this!

Disclaimer – this article is focused on cleaning green or white mold. If you’re dealing with brown or black mold, don’t attempt to remove this as you may make the mold spores airborne. Instead, this is worth calling a professional to take care of this with specialist equipment.

How Long Does It Take for Mold to Grow?

One of the most frustrating problems to have to deal with around the home is a leak. Leaks present immediate problems, such as damaging your things.

They can also lead to staining and discoloration of your floors, ceiling, and walls. But one of the scariest dangers is the mold that could crop up later if you leave the area untreated.

But, of course, it’s not just a leak that could invite mold into your home.

Mold could also pop up for many other reasons, such as humidity, leaks, condensation, poor ventilation, wet clothing, and a damp foundation.

But, how long does it take for mold to grow on certain surfaces and become visible? Check out the table below to find out and learn how quickly it can start showing spores:

Location of the MoldHow Long It Takes for the Mold to GrowHow Long It Takes for the Mold Spores to Become Visible
Hidden Surfaces24 to 48 hours24 hours
Hard Surfaces24 to 48 hours14 to 21 days
Attic24 to 48 hours24 hours
Wet and Warm Areas24 to 48 hours24 hours
Open Areas24 to 48 hours30 days or more

4 Areas in Your Home Where Mold Grows The Most & Tips to Prevent It

Now that you know how long it takes for mold to grow, it’s time for us to take a look at the rooms that mold is most likely to affect.

This guide will also give you some simple solutions to help prevent the build-up of mold in the home.

#1 The Bathroom

It is common for mold to grow around the shower and bathtub, under the sink, on the walls and floor, and behind the toilet.

A very minor leak in the pipes under the bathroom sink could attract mold. A cupboard under the bathroom sink could also begin to harbor mold. It could do so if cleaning equipment isn’t dried properly before it is stored under the sink.

Mold can also find its way between tile grouting on the floor and walls around the shower and bathtub.

Mold growing on bathroom tiles
Mold growing on bathroom tiles in a damp environment

Luckily, you can easily prevent mold from appearing in your bathroom by fixing leaking faucets and pipes, drying surfaces after cleaning them (such as the floor after mopping), and installing an extractor fan.

For a more reliable fix, you can also paint the bathroom with mold-resistant paint. The paint has a moldicide that reduces mold growth.

#2 The Kitchen

The kitchen has a variety of surfaces. Some of its surfaces are warm and wet, such as the area near the sink. The kitchen is also made up of hard areas and open spaces, such as the tiling and floor.

This makes it easy for mold to grow in some parts of the kitchen and harder for it to grow in others.

It is common for mold to grow in the kitchen under or around the sink, in the refrigerator, or in the microwave.

You see, mold can quickly spread around the sink because it is always damp and spores usually begin to grow in the place where you leave your wet sponge. It is also common to find them under, around, and on your drying rack.

Moreover, food that has passed its use-by date is also likely to grow mold. This can quickly spread, even if the food is kept inside the fridge. Food that is left out in the open is also a target for mold. This is especially true if it is left in a warm, enclosed space such as the microwave.

Don’t worry, though. You can easily avoid this situation from happening by fixing leaking faucets and pipes, drying countertops after cleaning them, and removing old food from the refrigerator. Moreover, cleaning spills in the microwave immediately, drying the dishes, and installing an extractor hood could also help.

#3 The Bedroom

Condensation can also cause mold spores to grow.

You see, condensation is caused when humid air meets a cold surface like your windows. This is why it’s recommended to clear condensation off the windows to prevent the issue.

Cleaning condensation
Cleaning condensation can help prevent mold growth

Moreover, you can also prevent mold from growing in your bedroom by repairing any leaks in the air conditioning. I also recommend using a bed frame with slats that will air the mattress and ventilate the room regularly.

If you have single-glazed windows, replacing these with double paned glass works great because it insulates the warm, moist air in the home from the cold glass on the outside. This prevents the inner glass from becoming cold and forming condensation – which leads to mold.

#4 The Attic

The attic and your insulation are prime areas for mold to grow. These hidden areas are warm and in the case of the attic are being heated all day by the rest of the home.

Spores could appear in the attic and insulation faster than anywhere else in the house.

One of the most important things to check is that your attic vents are functioning properly. Generally, gutter clogs will not cause moisture in an attic because they should be the lowest point on the roof, but these are still worth clearing. Clogged gutters will rot out the fascia boards and soffits if they are made from wood and not protected by cladding or paint.

How to Clean Mold Patches: 6 Simple Steps

Mold spreads quickly. So if you’ve found a patch of mold in the home, you’ll need to clean it immediately. Make sure you get rid of it ASAP before it becomes a bigger problem!

If the patch of mold isn’t too big, you should be able to tackle it yourself without calling in a professional. But there is a method for cleaning mold that will help keep you and your family safe. Take a look at it below.

You will need:

  • Gloves
  • Protective eyewear
  • A mask
  • Disinfectants


  1. Put on the protective gear: gloves, eyewear, and mask.
  2. Ventilate the area. Keep the windows and doors open while you are cleaning.
  3. Conduct a test patch. Clean a small area that has been affected by mold. If your health is severely affected, call a professional to clean up the rest.
  4. Clean all surfaces with a disinfectant. Let the solution rest on the surface for 10 to 15 minutes before rinsing it away with hot water. For hard surfaces, you’ll need to clean the mold away with a stiff brush. But, for porous materials, please use a sponge. You can also mix a small amount of bleach with water to kill white or green mold (as long as you can smell the bleach, there’s enough there).
  5. Dry the surface thoroughly. Keep an eye on porous surfaces. If mold resurfaces after a few days, discard the item or seek professional help.
  6. Keep the area ventilated after you have finished cleaning. This will ensure that the mold spores clear the atmosphere.


Mold grows quickly and spreads fast. It doesn’t take much for it to begin to appear in your bathroom, bedroom, kitchen, and other rooms in the house. This article has mentioned the most common places in the house that attract mold. The practical suggestions that were listed could help you to eradicate the problem.

If this article has been helpful to you, then why not check out some of our other articles and free guides? You could also sign up to our email list!

Have a great day!


Hi there! I’m Craig, and I’m the founder of Appliance Analysts. When it comes to appliances and anything electrical, I’ve always loved opening things up, figuring out how they work, and fixing them. This website is where I share free advice from myself and our experts to help our readers solve their appliance/HVAC problems and save money. Read more