Planter Drainage: Holes, Sizes and Setup

This is the one specification worth getting right before you order rather than after. Everything below comes from what Jay Scotts and Cosapots publish about their own planters, with their guidance linked so you can read it directly.

A note on these figures. This guide summarises what the two manufacturers currently publish. Specifications and warranty terms can change, and can vary by model. Check the documentation that comes with your planter, and where anything here differs from theirs, theirs is the one that counts.

Do outdoor planters need drainage holes?

Yes, if the planter will be outdoors. Jay Scotts put it plainly in their drainage guidance: if a planter is exposed to rain, snow or irrigation, drainage is necessary to prevent water accumulating. Cosapots specify drilled drainage for any outdoor use.

Jay Scotts give three reasons, and only the first is about the plant:

• It prevents water accumulating, which can damage the planter and affect plant health.
• It stops water freezing and expanding in colder climates, which they note can cause excessive expansion of the planter.
• It helps maintain the structural integrity of large planters, preventing warping.

Cosapots make the same cold-weather point, noting that draining sufficiently is notably important in regions that have freezing temperatures. Whether a planter can then be left out through the cold is a separate question, answered in our guide to fiberglass planters in winter. Indoors, or under permanent cover, an undrilled planter is perfectly usable and can hold a nursery pot as a cachepot instead.

One thing worth knowing before you decide. According to the Jay Scotts warranty, it is the purchaser's responsibility to ensure water can drain sufficiently from the container in outdoor use, and they note this matters particularly in regions subject to freezing. Drainage is not an upgrade, then. It is the condition their outdoor coverage assumes.

How many holes, and what size?

Jay Scotts publish an exact standard; Cosapots specify a bit size rather than a fixed count.

1–2 indrainage holes, every 12 inches of planter space. A 60 inch planter needs at least 4 to 5. Jay Scotts Drainage Hole Guidelines.

Cosapots publish the tool rather than the pattern: a 25 mm bit suitable for metal materials. The number of holes varies by model and size, so follow the guidance that comes with your planter, or simply have drainage added when you order.

Both figures come from the manufacturers' own guidance: the Jay Scotts drainage hole guidelines and the Cosapots warranty.

Drilled for you, or drilled by you?

Have it drilled at order. It is free from both brands, it is done to the manufacturer's own standard, and it is the only route that leaves nothing to interpretation.

Every planter on this site ships undrilled unless drainage is requested. The choice sits on the product page beside the size and finish, and you have to answer it before the planter can go in your cart, so nothing is decided silently. Choose yes and the holes are made to the manufacturer's specification at no extra cost.

The one irreversible part: a planter that arrives drilled is final sale, because drilling cannot be undone. That is the same for both brands. It is the reason the choice sits at the top of the product page rather than buried in the checkout.

Drilling later is allowed, and both brands publish guidance for it. But Jay Scotts state that they are not responsible for damage resulting from improper drainage if you create your own holes, and that failing to follow their recommended guidelines can lead to planter damage and is not covered by their warranty. If you drill it yourself, follow their published spec exactly.

Shop the collectionJay Scotts planters

Finished to order in 20 colors. Drainage drilled free on request, to their published 1 to 2 inch standard.

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Where to drill drainage holes

Across the base, spaced out, rather than one hole in the middle. Jay Scotts' self-drilling guidance is the same pattern they use themselves: 1 to 2 inch holes every 12 inches of planter space. On a 60 inch planter that means at least four or five holes, not one.

They add two conditions that are easy to skip. Account for environmental factors such as rainfall and irrigation, so a planter under a downspout or on an irrigated terrace needs the drainage sized for what actually reaches it. And for large or commercial installations they advise professional consultation rather than guessing.

Cosapots planters ship sealed, and their guidance specifies a 25 mm bit suitable for metal materials if drainage is drilled after delivery.

What if the planter has no drainage holes?

Use it as a cachepot, or have drainage added. Do not plant directly into an undrilled planter outdoors and hope the soil copes, because there is nowhere for the water to go.

The cachepot method is the reliable workaround: plant into a nursery pot that has its own drainage, sit it inside the decorative planter on a riser so it is not standing in runoff, and empty the outer planter after heavy rain. This keeps the planter undrilled and returnable, and it makes seasonal swaps easy.

It is a workaround rather than a fix. If the planter is staying outdoors permanently, drainage is the better answer.

Do you need gravel at the bottom?

No, and it makes drainage worse rather than better. This is the most persistent piece of bad advice in container gardening, and the reason it is wrong is physical rather than a matter of opinion.

Water does not move freely from a fine material into a coarse one. It has to saturate the fine layer first. Washington State University's work on container drainage describes the effect: gravitational water will not move from a finely textured soil into a coarser material until the finer soil is saturated. Adding gravel therefore lifts the saturated zone up into the root ball instead of draining it. The University of California's advice is the same: adding gravel to a planting container does not improve drainage.

What to do instead: potting mix all the way down, with a small square of landscape fabric over each hole to stop the mix washing out. That is the whole method.

One place the guidance differs, and it is worth being straight about. The Jay Scotts owner's guide sets out a layered method for planting: line the base with permeable landscape fabric, add a lightweight layer such as rinsed gravel or lava rock, separate that from the soil with a second layer of fabric, then fill with a well-draining potting mix. That is not the same as tipping gravel into the bottom and shovelling soil on top, because the fabric keeps the two from mixing. The research above is about the unseparated version.

So: if you are planting a Jay Scotts planter, follow their method. If you are simply wondering whether a handful of gravel in the bottom will help a pot drain, it will not.

Setting drainage up, step by step

1. Check the holes are clear. Look for packing tape, stickers or manufacturing debris over them.
2. Raise the planter off the surface. Feet or a riser let water escape sideways instead of pooling underneath, which is what stains a deck or terrace.
3. Cover each hole with landscape fabric, not gravel. A coffee filter cut to size does the same job.
4. Fill with potting mix all the way down. Jay Scotts specifically list heavy garden soil and fine sand among the materials not to use.
5. Water until you see runoff at the holes. That confirms the path is open and settles the mix around the root ball.

How to spot and fix root rot

Look at the roots. Utah State University Extension describes the difference plainly: infected roots become reddish-brown or black, whereas healthy roots are light brown or cream in color. Healthy roots are also firm; rotted ones are soft and the outer layer slips off easily.

The cause is standing water. USU note that the pathogen requires continually wet, warm soils to infect a plant, and that the prevention is planting in well-drained soil. In a container, that means the drainage was inadequate, blocked, or the planter was sitting in its own runoff.

To recover a plant: stop watering and let the mix dry, lift it out and cut away soft dark roots with clean tools, repot into fresh mix in a planter that drains, and fix whatever caused the water to sit. A mildly affected plant often recovers once the soil is allowed to dry out. A plant whose roots are mostly black will not.

Shop the collectionCosapots planters

Belgian-designed, in six stone finishes. Ships sealed; drainage drilled free on request.

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Frequently asked questions

Do all outdoor planters need drainage holes?

Yes. Jay Scotts state that a planter exposed to rain, snow or irrigation needs drainage to prevent water accumulating, and Cosapots specify drilled drainage for any outdoor use. Indoors, an undrilled planter is fine and works as a cachepot.

What size should drainage holes be?

As above: Jay Scotts specify 1 to 2 inch holes every 12 inches of planter space, at least four or five on a 60 inch planter. Cosapots specify a 25 mm bit suitable for metal materials.

Do large planters need more drainage holes?

Yes. The count scales with size rather than being fixed, so a larger planter simply gets more holes at the same spacing.

Can I drill drainage holes myself?

Yes, and both brands publish guidance for it. See the section above for what Jay Scotts say about responsibility and warranty coverage if you do. Having it drilled at order is free and avoids the question entirely.

Is a drilled planter returnable?

No. A planter that arrives with drainage holes added is final sale for both brands, because drilling cannot be undone. This does not affect your rights if a planter arrives damaged or defective.

Should I put gravel in the bottom of a planter?

No. Water will not move from fine potting mix into coarse gravel until the mix is already saturated, so a gravel layer raises the wet zone into the roots. Use potting mix all the way down with fabric over the holes.

Is it a problem if water sits under the planter?

Briefly, no. Persistently, yes: it keeps the base wet, stains the surface underneath and defeats the drainage. Raise the planter on feet or a riser so water can escape sideways.

Shop the collectionFiberglass planters

Planters from Jay Scotts and Cosapots, with the drainage choice on every product page.

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