Tuesday, November 11, 2014

A Terrific Terrarium

'The weather outside is frightful' across much of America with early snow and record cold temperatures. It's due to arrive in my backyard before the weekend. It is time, therefore, to plan some indoor gardening activities -- can't go too long without getting dirt under the fingernails.

How about making a terrarium?

Back in March this year, I attended the Home Gardeners' School at Rutgers' University, New Jersey. One of the classes was 'Terrarium Fundamentals' where I was able to make my very first one. This is what I learned:

Container choices:

Wardian cases (click for info) are lovely, but expensive. The Wardian case was popular in the nineteenth century and I love the antique look. You don't have to spend a lot of money on a suitable container, however. You can use a fish bowl, brandy sniffer, mason jar, spice jar, vase, candle holder, a cloche cover -- the possibilities are endless. Look for containers at the Dollar Store, floral supply store, garage sales, and maybe you have something around your house. The mouth size will determine if you use your hands or tweezers. You have to decide whether you want a covered or open container. My first attempt (pictured above) was open.

You may want to choose your plants first and that will help you decide your container type.

Plant selection:

Succulents work with an open container where they can receive more light. Ferns of all types, miniature orchids, miniature begonias, miniature African violets, and Soleirolii (Baby Tears) are some examples. In my terrarium I used Hypoestes (Polka dot plant), Sagina (Irish moss), Selaginella (Club moss), and Isolepsis (Fibre optic grass). Tillandsia (air plants) are suitable, too -- they don't need soil and love the humidity. Miniature begonias also like the humidity, but don't like wet feet, so add pearlite to the growing mix.

Materials and step-by-step instructions:

You will need a stick or planting item and a spray bottle.
  • Place a layer of coarse sand on the bottom to hold water. 
  • Add pea gravel.
  • Place a coffee filter over the gravel (to separate it from the potting mix.)
  • Add potting mix (if planting succulents use a specially formulated mix.)
  • A small amount of activated charcoal will help prevent algae.
From bottom to top: sand, gravel, filter, and potting mix.
My container is like a small goldfish bowl.

  • Use your stick to make holes in the potting mix as you plant. 
  • Water your finished creation utilizing a spray bottle.

Sagina Irish moss
Selaginella Club moss
Isolepsis Fibre optic grass
Hypoestes Polka dot

Accessories are optional, but it is fun to create a theme such as animals, the beach, or Asian. I chose a simple nature theme and accessorized with small cones and rocks.

Care for your new terrarium:

Heat - Excessive heat is a main cause of death in terrariums. Closed glass containers trap and hold heat, so it is important that you don't place it above radiators or in direct sunlight.

Light - Place your newly planted terrarium in shade for about a week, then adjust the light according to the plants' requirements. Most terrariums prefer diffused or filtered light. If they receive too much sun the leaves will wilt and develop burned spots. In too little light, plants develop tall, thin stems that are weak and unable to hold up leaves. Increase the amount of light slowly.

Water - With an open terrarium test the potting mix before watering. For plants that like moist soil the top earth should feel barely moist before you add water. For cacti and succulents, touch below the surface layer where it should be only slightly damp. Closed terrariums rarely if ever need water.

Troubleshooting - Excessive water encourages the growth of molds and causes plant decay. If the walls of the terrarium have more than 25 percent condensation, remove the cover until the walls clear. In a closed terrarium there should be only occasional clouding. The presence of mold or mildew indicates that something is wrong. The terrarium may contain too much water and have poor air circulation. Correct this by opening/removing the lid, providing air circulation and allowing the soil to dry out.

I left the class with my terrarium and with the added bonus of a small pot of sedum plugs donated by the presenter. I used the plugs when I made my first fairy gardens.

Sedum plugs for my next venture.

Making a terrarium is a great indoor activity for the winter months. I have one of those Warden cases on my Christmas wishlist ... hint, hint (H.H. reads all my postings.)

Have you made a terrarium yet? If not, do give it a try.

Pamela x

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I look forward to visiting your blog in return.


  1. It's lovely. Who says gardening has to stop in winter?

  2. The kids and I made some terrariums a couple years ago before we moved, and it was so much fun! This winter I'll have to make a new one. An added bonus of terrariums vs. houseplants - my cat can't eat the plants out of the closed terrarium!

  3. Great instructions. I'll be looking out for suitable containers every time I go near a shop now!

  4. Nice instructions. I remember in the 70's when these were really popular. I made them for a florist shop and they sold very well. Do you sell the ones you design? You should.

    1. Thanks, Donna. I don't sell them, but I'm developing a new workshop, "Designing Miniature Gardens and Terrariums." I teach gardening classes for older adult learners at the university, and I think they will like this. Fairy gardens and terrariums can be made by the elderly who do not have a garden, or can no longer maintain one.

  5. that polka dot plant was one of the nameless new to me ones I found in the new garden. It confuses me as our usual indigenous Hypoestes are tough tall garden shrubs.

  6. That is really interesting! Thanks for sharing the inspiration and great lesson.

  7. What a great idea for the coming months when we're stuck inside! Your terrarium is pretty and I also like the colorful primrose on your counter. Thanks for the informative article. -Beth

  8. This is beautiful. What a talent you have. I love the addition of the polka dot plant for colour. Do you just trim the plants back as they grow to keep things in proportion?

    1. I haven't needed to trim them back, Marguerite, but I don't feed them, or they would soon grow too big.

  9. These are a fab idea Pam...wonder where I could squeeze one of these indoors?
    Hmmmmm....maybe I could convert the bath tub?

  10. I think your class on this will go over well at the university, it's a perfect activity for winter when the snow and ice seems relentless and spring so far away.

  11. I have wanted to make a terrarium for a couple of years now so now with time indoors it is perfect...And Pam I love the directions you give and will hopefully give this a try for the holidays and winter.