Yes, glazed like the olla, and it goes back on after each refill to keep mosquitoes away.

Remove the olla when it empties noticeably more slowly than when first installed. Pour white vinegar into the reservoir and leave it to work. Rinse thoroughly with clean water. Wipe the glazed section with a damp cloth, without detergent. Replant it, pressing the compost firmly around the tip.

Grey planting olla – terracotta irrigation pot with grey finish for designer planters

Grey olla close-up – slow water diffusion for indoor and balcony potted plants

Terracotta planting olla – passive irrigation for vegetable garden and potted plants

Grey olla in situ – eco-friendly watering in the vegetable garden and planters

Olla for planting, grey glazed terracotta

20,90 €

Size	Price	Price per L	vs 15 cl
15 cl	20,90 €	139,33 €	—
30 cl	22,90 €	76,33 €	−45 %
50 cl	27,90 €	55,80 €	−60 %

This olla has a grey glaze on its visible section, while its tip remains bare terracotta to allow water to diffuse into the compost. It comes in 15, 30, and 50 cl, lid included, for an indoor pot or a balcony planter.

Olla irrigation

Size : 15 cl

15 cl

30 cl

50 cl

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Delivery within 2 to 15 business days

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The summary

The finish: grey enamel on the visible body, a bare terracotta tip.
The three sizes: 15, 30, or 50 cl — the 50 cl version is enamelled over the entire body.
Release rate: 24 to 36 hours of diffusion; one bottle for periods away from home.
How many per planter: one olla every 20 to 24 cm or so.
Winter: a frost-resistant clay — the olla stays in place.
Maintenance: white vinegar when the release rate slows noticeably.

Olla glazed in grey on its visible part, for pots and planters.

The Agrotonome grey glazed terracotta planting olla is an irrigation olla for pots and planters. Its grey glaze covers the visible part, while the tip is left as bare terracotta to release water into the compost. Available in 15, 30 and 50 cl, it empties in 24 to 36 hours.

Planted in an indoor pot or a balcony planter, an olla remains visible all year round. This model has a grey glaze on the section that sits above the compost, while the tip remains in bare terracotta to allow water to diffuse through it. Available in 15, 30 and 50 cl, lid included.

🎨 A glaze on the visible part

A glaze seals the pores of terracotta, so a glazed surface no longer allows water to pass through. On this model, the glaze covers the upper section, the part you see, while the buried section and the spike remain bare terracotta: it is through these that water travels through the clay into the compost, drawn by the tension of drying soil. The unglazed model is bare along its full height. On the 15 cl and 30 cl sizes, the glaze covers the upper half of the reservoir; on the 50 cl, it covers the entire body and only the spike remains bare. The glazed section loses no water to the air, so all the diffusion is directed into the compost.

🕒 How often to fill it

A full olla drains in approximately 24 hours for the 15 cl, between 24 and 36 hours for the 30 cl, and around 36 hours for the 50 cl. In the height of summer, on a sun-exposed window box, refilling becomes a daily task. These timings apply to the first fill: during the first week, the compost around the olla reaches equilibrium and the reservoir empties more quickly. Before the first use, soaking overnight in a bowl saturates the clay and slows diffusion, this matters most with the smallest size.

For an absence of a few days, the reservoir can be extended with a bottle of water, ideally glass, with the neck turned upside down and inserted into the opening of the olla. Place the planter in the shade while you are away, and lay a mulch over the compost around the neck so that the water diffusing through stays available to the roots for longer. Together, these measures noticeably extend the autonomy of a balcony planter.

The top-up bottle only stays stable when sheltered from the wind

A full bottle planted in a small olla sits tall and top-heavy, and a gust of wind is enough to knock it over and pull the olla clean out of the compost. Push the olla in deep before sliding the bottle in, and keep this method for pots and planters that are sheltered from the wind. On an exposed balcony, move the pots close to the wall when you are away.

Light potting compost around a planter olla

If you're planting up a new planter, fill it with a lightweight peat-free compost and press it gently by hand against the tip of the olla. Made from composted pine bark, coir fibre, wood fibre and perlite, it holds the moisture the olla delivers while remaining well aerated. Its light fertiliser content also gives you full control over any additional feeding, which is applied to the surface rather than inside the olla.

📐 Several ollas in one planter

The moistened zone around an olla is roughly twice its diameter. With an 8 cm diameter, a 15 cl olla moistens a volume approximately 16 cm wide, a 30 cl one approximately 20 cm, and a 50 cl one approximately 24 cm. In a planter, space the ollas that same distance apart to achieve evenly moist compost from end to end, and place the plants as close to them as possible, since their roots need to reach the wall.

40 cm planter

2 ollas of 30 cl, or 2 of 50 cl if the planter is deep enough.

60 cm planter

3 ollas of 30 cl, or 2 to 3 of 50 cl staggered between plants.

80 cm planter

3 ollas of 50 cl spaced evenly, one between each group of plants.

Indoor pot

1 olla per pot, from 15 cl up to 15 cm in diameter, from 30 cl beyond that.

Depth matters as much as length: the olla is buried almost entirely, with only its upper section above the compost, which requires at least 15 to 18 cm of growing medium depending on the size. In a shallow planter, the 30 cl size is often the largest that will fit. Dimensions vary by around 10% from one piece to the next, as with all terracotta, so it is worth measuring your planter with a little margin to spare.

🧽 Limescale, frost and cleaning

Minerals dissolved in tap water and rainwater alike settle into the pores of the unglazed surface and gradually block them, causing diffusion to slow over the seasons. When your olla empties noticeably more slowly than it did at first, remove it from the compost, pour white vinegar into it, leave it to act, then rinse thoroughly. The clay used is frost-resistant, and the olla can remain in a planter outdoors throughout winter. A mulch of dead leaves over the compost protects roots during hard frosts. The guide watering your plants with an olla expands on these tips.

Technical specifications

The essentials

Capacities: 15, 30 and 50 clThe 50 cl bottle is enamelled over the entire body, the other two over their upper half.
Dimensions: Ø 8 x 15 cm to Ø 12 x 18 cm30 cl: Ø 10 x 16 cm. Approximately 10% variation between individual pieces.
Diffusion duration: 24 to 36 hoursFor a full olla, from the 15 cl to the 50 cl, at the first filling.
Finish: Grey enamel, bare tipThe water passes through the bare terracotta, buried in the compost.
Weight: 0,25, 0,65 and 1,1 kgFor the 15, 30 and 50 cl sizes.
Manufacturing: Alsatian terracottaClay is frost-resistant: the olla stays in place through winter.

To budget for separately

A glass bottle: For periods of absenceIts neck folded back into the opening extends the reservoir by a few days.
A mulch: Around the neckIt keeps the diffused water available to the roots for longer.

In the box

1 olla with a grey glazed finish, in the chosen capacity.
1 matching lid

Capacities, dimensions, weights, diffusion times, finish and frost resistance: manufacturer's data, recorded on 07/10/2026. Humidified area: approximate figures from the agricultural extension services of the Universities of Arizona and North Dakota.

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delivery time

Fragile terracotta, packed piece by piece. If you order several to fit out an entire bed, they are shipped together in the same parcel. The exact shipping cost is shown in the basket once your address has been entered.

Frequently asked questions

8 questions

6 key questions, 8 in the detailed view

Does the enamel prevent the olla from working?

What is the difference from the bare model?

Feature	Grey	Raw
Visible surface	Glazed	Bare clay
Evaporation through visible surface	None	Slight
Capacities and duration	Identical	Identical

The raw model retains the natural clay colour.

How often does it need refilling?

How many ollas for one planter?

Planter	30 cl	50 cl
40 cm	2	2
60 cm	3	2 to 3
80 cm	4	3

Is the lid included?

Does it need bringing in for winter?

Can fertiliser be added to it?

How to maintain it?

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Olla for planting, grey glazed terracotta

The summary