Jesmonite® Plant Pots: How to Make Indoor & Outdoor

Not sure how much to mix? Use our free Jesmonite® calculator — enter the water weight of your mould and it gives you the exact liquid and base amounts.

Which Jesmonite® for plant pots (indoor vs outdoor)

The single most important decision is the material, and it depends on where the pot will live.

For indoor decorative pots, reach for AC100. It is the beginner-friendly, water-based variant for indoor homeware like trays, vases and pots. It is non-toxic and solvent-free, demoulds after about 30 minutes, and is fully cured after 24 hours. AC100 is porous, so seal it (and add a drainage hole) if you want to plant straight in, or use it as a decorative cover pot around a plant.

For outdoor planters that face rain, frost and sun, do not use AC100. Choose AC730, a tough, cement-based variant that gives a lovely stone or textured look and is rated for indoor and outdoor use. Alternatively, AC84 is a versatile, weather-resistant cement-based option that also works indoors and outdoors and is easy to pour.

Whichever outdoor material you pick, Jesmonite® is porous by nature, so an outdoor piece must be sealed with a penetrating or Flexiguard sealer before it goes outside. That invisible barrier keeps water out without changing the look.

What you will need

• Your chosen material: AC100 for indoor, or AC730 / AC84 for outdoor
• A silicone pot mould
• Accurate digital scales (weighing is the whole game)
• Mixing tubs and a stirrer, or a high-shear mixer on a drill
• Optional pigments to colour the mix; for a terrazzo effect fold in small Jesmonite® chips you make yourself, or use ready-made StoneRoxx as an alternative for a similar speckled look
• A penetrating sealer for outdoor pots, plus P150 sandpaper and a sanding block for finishing

New to casting? An AC100 starter kit bundles the essentials so you can get straight to making.

Step-by-step: casting a pot

1. Work out how much you need. For AC100, measure the volume of water needed to fill the empty mould, and add about 10% spare since some mix stays in the cup. Divide that water amount by 2 to get your Jesmonite® liquid, then multiply the liquid by 2.5 to get your Jesmonite® base. For AC84 or AC730, use an online Jesmonite® calculation tool or the Jesmonite® app to work out quantities. See our full guide on how much Jesmonite® you need.
2. Weigh and mix. Use the correct ratio for your material: AC100 is 1:2.5 Jesmonite® liquid to base, while AC84 and AC730 are 1:5. Add the Jesmonite® base to the Jesmonite® liquid and mix thoroughly until smooth and lump-free; a high-shear mixer helps. Too much liquid gives a soft, chalky result and too little sets thick and fast, so accurate scales matter.
3. Colour it (optional). A little pigment goes a long way and gives a solid, opaque colour. Stir it in fully, or fold in stone chips for a speckled finish.
4. Beat the bubbles. Pour slowly in a thin stream from about 10 cm up, then gently tap and vibrate the mould so trapped air rises to the surface, and pop any surface bubbles with a toothpick, tapping is the main way to keep your cast bubble-free. Only for moulds with a lot of fine detail, you can first brush a thin layer into the cavity, but for most pieces this isn’t needed. For larger pieces or very detailed moulds, a vibration plate makes releasing bubbles even easier.
5. Demould at the right moment. AC100 is usually ready to release after about 30 minutes. Do not leave the cast in too long, as it can sweat and pick up surface marks; around 30 minutes is a safe window.
6. Sand, then cure and seal. Sand any edges with a block and P150 sandpaper as soon as possible after demoulding, while the cast is still relatively soft and easier to work. Then let the pot cure for 24 hours as it reaches full strength before sealing or planting.

Making it safe for live plants (drainage and sealing)

Jesmonite® is porous, so plan for water before you plant anything. You have two easy routes, pick whichever suits your plant.

Plant straight into your pot. You don’t need a plastic liner. Add a drainage hole (the simplest way is to drill one once the pot is fully cured) so water isn’t left standing against the walls, and seal the pot so moisture can’t soak in. Stand the finished planter on a saucer.

Or use it as a decorative cover pot. If you’d rather not seal or drill, keep the plant in the pot it came in and drop that inside your Jesmonite® pot. Your cast becomes a decorative cover, and you can lift the plant out to water it at the sink.

Outdoor planters. Any pot that lives outside should be cast in AC730 or AC84, then sealed with a penetrating or Flexiguard sealer once fully cured. This gives invisible water protection so rain and frost cannot soak into the material, which keeps an outdoor planter looking good season after season. See our guide to sealing Jesmonite® for the method.

Ready to cast your first planter? Pick a shape from the moulds collection, choose AC100 for indoor or AC730 for outdoor, and start making pots you will actually want to display.