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Growing Stalactites

Stalactites and Stalagmites are those impressive pillars you see growing in caves.  If you aren't sure which is which, just remember that stala'G'mites grow from the 'G'round.  Now that you know how to tell a stalactite from a stalagmite, find out how to grow your own.

Continue reading "Growing Stalactites"





Growing Stalactites

stalactite growing on cotton string


Epsom salts
2 identical glasses
string or paper towel
2 paperclips or weights
bowl or pot


  1. Fill the glass right to the top with water and dump it in the bowl or pot.  Do it again.
  2. Start adding Epsom salts and stir to dissolve.  Keep adding Epsom salts and stirring until they won't dissolve.  
  3. If you are using a pot, heat the pot on a stove.  You should be able to dissolve more Epsom salts in a hot solution.  Don't let the solution boil, but keep it on the stove until it is very hot.  Add more Epsom salts and keep stirring.
  4. Divide the solution into the two glasses.  
  5. Find a location where they won't be disturbed for a few days.  There will be some dripping.  If you are putting them on a wood table, be sure to put a tray or something else under the glasses to protect the table.
  6. Cut a string.  It needs to be long enough to cover the distance between the glasses and hang down to the bottom of both glass.  Or use a rolled up paper towel to connect the two glasses.
  7. Put the paperclip on each end of the string.  Put one end of the string in each of the glasses.  There should be a slight dip between the two glasses.
  8. Watch as your stalagmite and stalactites grow over the next few days.

stalactite growing on paper towel

I've read about this experiment many times over the years.  The directions always make it look simple.  When it works, it is easy.  But there are lots of variables you can change if you aren't getting results.



  • You need to dissolve a lot of Epsom salts in the water.  The stronger the solution, the faster you will see results.  If you need to grow something overnight, be sure to heat the solution and slowly dissolve as much Epsom salts as possible.
  • You can submerge the string in the solution first so that it is all damp before putting it in the two glasses.
  • Check the string.  If there is a dip below the height of the water, there will be a lot of dripping.  You can get a pool between the two glasses.  When the drips fall too quickly, there's no time for the stalactite to form.  Move the glasses slightly apart to raise the height of the string just a bit.  It should slow down the dripping.  Move the glasses closer together if there is no dripping and the string dries out.
  • Paper towel sucks up a lot of liquid and may be the fastest way to grow your stalactite.  
  • Your results will depend on the humidity in your home.  The results should be more dramatic in a home with a lower  humidity.
  • If your string keeps drying out, you can use an eye dropper to add one drop of the solution to each side of the string about once an hour.
  • If you aren't allowed to heat the solution over the stove, ask if you can boil some water.  Put the hot water in the bowl and add the Epsom salts directly to the hot water.  You can use hot water from the tap.  
  • I've dissolved a lot of chemicals in water to make solutions for growing crystals.  It takes a LOT of Epsom salts to get a super saturated solution.  
  • Use a natural fiber sting like cotton or wool. 



Learn more about Stalactites and cave features

How stalactites Form

What's a Speleotherm?


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