Root rot is one of the most common issues gardeners face when growing plants in outdoor planters. It can affect everything from bedding plants to shrubs and even small trees. Thankfully, with the right planter setup and a few simple care habits, root rot is entirely preventable.

If you’ve ever had a plant suddenly wilt, yellow, or collapse despite what seems like good care, root rot may be the underlying cause. In this guide, we explain what root rot is, how to avoid it, and why choosing the right planter—especially one with proper drainage—is the best defence.

What Is Root Rot?

Root rot occurs when plant roots sit in overly wet, oxygen-poor soil for too long. Without airflow, roots begin to suffocate and decay, and fungal pathogens quickly take advantage. When rot sets in, plants struggle to absorb water and nutrients, eventually showing visible decline.

In planters, root rot is almost always linked to:

• Poor or blocked drainage
• Overwatering
• Soil that holds too much moisture
• Planters without drainage holes

Fortunately, root rot is easy to avoid with the right planter choice and good watering habits.

1. Start With the Right Planter (Drainage Is Essential)

At Planters.co.uk, the majority of our planters are designed specifically to reduce the risk of root rot by allowing excess water to escape freely.

Most of our planters include:

• Drainage holes & bungs (in Zinc and Corten planters) to allow you to control drainage depending on where the planter is placed
• Integrated drainage systems in wooden designs to ensure water does not pool around roots

This makes our planters ideal for outdoor use where healthy drainage is crucial.

The exceptions?

Our barrel planters and some round planters, which are also popular for use as container ponds. For customers using them strictly as planters, drainage holes can easily be drilled—a quick solution that immediately improves airflow and prevents waterlogging.

Always check the product pages for the correct information on drainage about each product.

2. Use the Right Compost for Drainage

Even with excellent drainage holes, your compost must allow water to pass through freely.

Choose breathable, well-draining mixes such as:

• Multi-purpose compost for general planting
• Soil-based composts like John Innes No. 3 for shrubs and trees

Improve drainage further by mixing in:

• Perlite
• Horticultural grit
• Bark chips

Avoid compact, heavy garden soil in planters—it holds too much water and increases the risk of rot.

3. Water the Right Way

Plants in outdoor planters need consistent watering, but not constant moisture. The trick is to water deeply but allow the soil to dry slightly between waterings.

Healthy watering habits:

• Water until you see moisture draining from the base
• Allow the top 2–5 cm of compost to dry before watering again
• Never leave planters sitting in full water trays or saucers
• Reduce watering during cooler months

If your planter from Planters.co.uk includes bungs, you can remove them during rainy periods to increase drainage.

4. Raise Your Planters for Better Drainage

Even planters with drainage holes can suffer if these holes sit flat against hard paving.

Use pot feet or risers to:

• Improve airflow under the planter
• Prevent blockages
• Help water flow away freely

This is especially important for larger, heavier planters like Corten steel, fibreclay, and wood.

5. Choose Suitable Plants for Containers

Some plants tolerate consistently moist conditions; others require fast-draining soil. Matching the right plant to the right drainage environment will protect against root rot from the start.

Good choices for well-draining outdoor planters:

• Lavender
• Rosemary
• Olive trees
• Bay trees
• Hebes
• Ornamental grasses

Plants that prefer moisture:

• Ferns
• Hostas
• Japanese iris

These should only be planted in moisture-retentive composts or in planters designed to hold more water.

6. Refresh the Soil and Repot When Needed

Over time, compost naturally compresses and becomes less free-draining. Roots may also fill the pot completely, restricting airflow.

Every 2–3 years:

• Repot into a slightly larger container
• Refresh the compost
• Trim away any mushy or damaged roots

Even long-term container trees benefit from fresh soil around their rootball annually.

7. Know the Early Signs of Root Rot

Catching the symptoms early can save your plant.

Warning signs include:

• Yellowing leaves despite moist soil
• Wilting even when the compost is damp
• A foul smell when you inspect the roots
• Mushy, brown, or blackened roots
• Soil that stays wet for days

If root rot is spotted, repot immediately using fresh compost and ensure drainage is improved.

Final Thoughts: Healthy Roots Start With the Right Planter

Root rot is almost always preventable—and choosing a planter with proper drainage is the most important step of all. At Planters.co.uk, the vast majority of our planters come ready with drainage holes, bungs, or integrated drainage systems, giving your plants the best chance to thrive.

For barrel and round planters used for ponds, drainage holes can be drilled easily when needed for planting—giving you full flexibility.

With the right planter, good-quality compost, and sensible watering habits, your plants will remain vibrant, healthy, and beautifully displayed year-round.