Planting Hardy Exotic Plants: A UK Garden Guide

Getting a new outdoor plant off to a strong start comes down to three key factors: choosing the right location, planting it in free-draining soil, and making sure it is planted at the correct depth. When these essentials are in place, hardy exotics will establish quickly and have a much better chance of thriving through a British winter. This guide explains everything you need to know about planting hardy exotic plants in UK gardens, from selecting the perfect spot to watering, mulching and caring for your plants during their first year.

What counts as a hardy exotic?

Hardy exotic plants bring a tropical look to the garden while being able to survive UK winters outdoors, either without protection or with a little seasonal care. The RHS classifies plants using hardiness ratings from H1, which require heated greenhouse conditions, through to H7, which are extremely hardy. Most plants in our hardy exotics range fall within the H3 to H5 categories, making them suitable for many UK gardens.

Some of the most reliable choices include:

• Windmill Palm (Trachycarpus fortunei) is rated RHS H5, making it hardy across most of the UK. It is one of the easiest palms to grow outdoors and forms the backbone of our hardy palms collection.
• Hardy Banana (Musa basjoo) is rated RHS H4. While its underground rhizomes are extremely hardy, the pseudostem benefits from winter protection if you want to preserve its height.
• Clumping Bamboo (Fargesia 'Jiuzhaigou') is also rated RHS H5. Unlike running bamboos, it grows in neat clumps and will not spread invasively.
• Tree Fern (Dicksonia antarctica) is generally rated around RHS H3 and usually requires its crown to be protected during winter.

As a guide, RHS H4 plants are hardy through most of the UK and can typically tolerate temperatures between around -10°C and -5°C, while H5 plants cope with temperatures between approximately -15°C and -10°C. Always check the hardiness rating for your specific plant rather than assuming all exotic-looking plants have the same tolerance. It is also best to avoid planting tender species in exposed frost pockets.

Choosing the right position

Choosing the right location is one of the most important parts of successful planting. Shelter is often more valuable than extra warmth. Large-leaved plants such as bananas and cannas can suffer badly in strong winds, while cold winds dry out the foliage of palms and tree ferns faster than the roots can replace lost moisture.

Look for a planting position that is protected by a fence, wall, hedge or established shrubs, which will reduce the impact of prevailing winds.

Most hardy exotics, including palms, bananas, agaves and bamboos, grow best in a position that receives at least half a day's direct sunshine. Tree ferns and many hardy ferns are the exception, preferring dappled shade or protection from the afternoon sun along with consistently moist soil. Planting near a south or west-facing wall can also provide extra warmth, as masonry absorbs heat during the day and slowly releases it overnight.

Preparing the soil and improving drainage

Poor drainage is responsible for far more losses than cold weather alone. Cold, waterlogged soil encourages root and crown rot, so taking the time to prepare the planting area properly will make a significant difference to long-term success.

Dig a hole approximately twice as wide as the rootball, keeping the depth the same. Loosen the sides and base of the hole with a garden fork so that new roots can spread easily into the surrounding soil.

If you have heavy clay soil, mix plenty of horticultural grit and garden compost into the excavated soil before backfilling. This improves drainage while maintaining healthy soil structure. If your soil is naturally sandy and free-draining, add compost instead to help retain moisture and nutrients during the growing season.

In gardens that remain wet throughout winter, consider planting slightly above ground level or building a shallow raised mound. Raising the crown even a few centimetres can significantly reduce the risk of winter rot.

How deep and how far apart to plant

Plant your hardy exotic at exactly the same depth as it was growing in its nursery pot. The top of the rootball should sit level with the surrounding soil, or very slightly above it if drainage is poor. Planting too deeply increases the risk of crown rot, particularly in palms and tree ferns.

Spacing should always be based on the mature size of the plant rather than the size of the pot it arrives in. While closer planting can create an instant jungle effect, leaving enough room for airflow helps reduce the risk of fungal diseases.

How to plant outdoors

Begin by watering the plant thoroughly while it is still in its pot around an hour before planting. This ensures the rootball is fully hydrated.

Dig and prepare your planting hole so that it is twice as wide as the rootball and the same depth.

Carefully remove the plant from its pot and gently loosen any tightly circling roots.

Place the plant into the hole and check that the top of the rootball sits level with the surrounding soil. On heavier soils, allowing it to sit slightly proud can improve drainage.

Backfill the hole gradually, gently firming the soil with your hands as you go. This removes large air pockets without compacting the soil excessively.

Finally, create a shallow watering basin around the plant by building a small rim of soil around the edge of the planting hole.

Staking and watering in

If your plant is tall or growing in an exposed position, it may benefit from being staked during its first year or two. Use a short stake with a soft, flexible tie that allows a little movement, as this encourages the plant to develop stronger roots. Remove the stake once the plant is well established.

Water thoroughly immediately after planting so that the soil settles around the roots. Continue watering regularly throughout the first growing season, particularly during dry weather. Even drought-tolerant plants such as agaves need consistent watering while they establish. Allowing a newly planted exotic to dry out during its first summer can slow its development considerably.

Mulching and the first winter

Once the plant has been watered in, apply a layer of bark, compost or leaf mould a few centimetres deep over the root area. Keep the mulch clear of the stem or crown to prevent excess moisture collecting around the plant.

Mulching helps retain moisture during summer, suppresses weeds and provides valuable insulation during winter. It is one of the simplest and most effective ways to support newly planted exotics.

During the first winter, it is worth following the four-degree rule by preparing winter protection when temperatures begin approaching 4°C. Wrap banana pseudostems with horticultural fleece and straw, fill tree fern crowns with dry straw or fleece, and apply additional mulch around the roots of more tender plants. Fully hardy plants such as windmill palms and Fargesia bamboo usually require little more than a generous mulch once established.

When is the best time to plant?

The ideal time to plant hardy exotics is from mid-spring through to early summer. At this time of year the soil is warming up, giving plants plenty of time to establish before winter arrives.

Planting throughout summer is also perfectly suitable, provided you keep plants well watered during dry spells.

Autumn planting can work well for the toughest species, including windmill palms and clumping bamboos. However, it is generally best to avoid planting more tender exotics from October onwards, as young plants have much less time to establish before cold, wet weather arrives. Waiting until spring usually gives these plants the strongest start.

Ready to grow your outdoor garden?

Browse our hardy exotics collection to discover plants suited to your garden conditions, or explore our hardy palms collection if you're looking for an easy way to create a tropical feel. Every plant is carefully packed and covered by our Live Arrival Guarantee, so it arrives in excellent condition and ready to thrive.