Ollas, also known as oyas, are irrigation systems that have been used for thousands of years. Eco-friendly, economical and efficient, this watering technique offers numerous advantages.
The olla system provides gentle watering through capillary action, directly to plant roots, without any waste. It can be used in vegetable gardens, ornamental gardens, greenhouses, or even in pots.
Ollas are becoming increasingly available in garden centres or online. But it's also possible to make your own watering pot quickly, without a potter's wheel or advanced DIY skills!
Follow our tutorial to create small and large homemade ollas at low cost, and watch Olivier's video on watering with the oya technique
Choosing the right pottery in advance
The material used for making ollas must be porous, unglazed, untreated and not waterproof. Standard terracotta pots found in garden centres for a few euros are perfect. You can also use reclaimed pots.
The size of the pot should match the water needs of the plant. For 1-2 tomato, aubergine or pepper plants, a 15cm diameter olla works well (holding about 1L of water). Choose a larger container for shrubs, smaller for potted plants.
Making a small olla
The small olla is particularly suitable for potted plants or annuals in vegetable or ornamental gardens.
Materials needed
- A terracotta pot
- A saucer or plate matching the pot's top diameter
- Optionally: a terracotta shard, tile fragment or aluminium washer
- Optionally: silicone, filler paste, tile adhesive or mortar
Construction steps
- Seal the drainage hole at the bottom to prevent water leakage: fix the shard or washer inside the pot using your chosen sealing material. You can also use repair putty moulded to fit the drainage hole.
- Let it dry for a few hours.
- Check for leaks: place the pot on the saucer, fill with a few centimetres of water, wait 1-2 hours and ensure no water escapes through the drainage hole. If leaking occurs, repeat step 1.
Your small olla is ready!
Making a large olla
The large olla is better suited for perennials or larger plants (shrubs, fruit trees...) in the garden.
Materials needed
- 2 terracotta pots of the same size
- A saucer or plate matching the pot's base diameter
- Optionally: a terracotta shard, tile fragment or aluminium washer
- Optionally: silicone, filler paste, tile adhesive or mortar
Construction steps
- Seal one drainage hole at the bottom of one pot to prevent water leakage. The second hole must remain open for filling.
- Invert the pot with the open hole and place it on top of the sealed pot, with openings aligned.
- Join the two pots together using your chosen sealing material.
- Let dry for a few hours.
- Check for leaks: fill through the hole with a few centimetres of water, wait 1-2 hours and ensure no leakage occurs. If leaking occurs, repeat step 1 or 3.
Your large olla is ready!
Installing a homemade olla in the garden
Installation should be done either:
- Before planting
- After planting, close to the plant while taking care not to damage roots when burying it
An olla typically waters plants within 1.5 times its diameter (a 15cm olla irrigates about 22cm diameter).
Don't hesitate to install multiple ollas in vegetable rows or around shrubs.
Avoid placing them in pathways to prevent damage.
- Dig a hole matching the olla's height and diameter.
- Bury the olla leaving 2cm above ground (about the saucer's height for stability). Ensure it's level with no air pockets.
- Firm the soil around the pot.
- Fill with water using a watering can or hose.
- Cover with the lid (saucer or plate).
- Mulch to retain moisture and reduce evaporation.
Installing an olla during planting: the sealed terracotta pot is placed in soil, filled with water and covered with a saucer. Plants are planted around the olla. (photo steveilott)
Check water levels easily by lifting the lid. Refill when empty. Typically lasts 5-7 days depending on weather.
Tip: for large ollas, use a straw or stick inserted in the hole to check water levels.
In winter, remove ollas from soil, clean with water and black soap, and store until next season. Ollas left in place should be protected with thick mulch. Never fill when temperatures are below freezing to avoid cracking.
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