Growing Eucalyptus in the UK
- Jane Westoby
- 3 days ago
- 5 min read
Understanding Eucalyptus (What Actually Matters)
Eucalyptus species are evergreen trees or large shrubs that are widely grown for their fast growth, aromatic foliage, and ornamental value. When grown from seed, their germination behaviour can vary depending on the species, seed provenance, and seed freshness, which is why understanding eucalyptus dormancy is key to successful propagation.
Eucalyptus plants are sun-loving and require full light from an early stage to grow strongly and develop sturdy stems. Low light levels result in weak, stretched growth, particularly in seedlings. Once established, eucalyptus are fast-growing plants, but they are sensitive during their early stages and do not tolerate poor conditions well.
Although eucalyptus are evergreen and not deeply winter-dormant, they are highly responsive to seasonal temperature changes, particularly during germination. Young eucalyptus seedlings are especially sensitive to waterlogged compost, which can quickly lead to root problems or failure. Free-draining conditions are essential, especially in cooler weather.
Crucially, eucalyptus seed dormancy is conditional rather than absolute. Some seeds may germinate without cold treatment, while others require a period of chilling to break dormancy. This variability explains why germination can appear inconsistent if seed is sown without preparation. Pre-stratifying eucalyptus seed before sowing removes this uncertainty and leads to more reliable and even germination.
Do Eucalyptus Seeds Need Cold Stratification?
Eucalyptus seeds do not always require cold stratification to germinate, but in some cases it can be critical for reliable results. This is also where much of the confusion and misinformation around eucalyptus seed sowing comes from.
Many eucalyptus seeds will germinate without any cold treatment when surface sown and kept at a steady temperature of around 18–22 °C. Under these conditions, germination can occur naturally, particularly with fresh seed or certain species. However, if seeds fail to germinate within four to six weeks, a period of cold often helps to break dormancy and trigger growth.
This behaviour is known as secondary dormancy and is common in woody plants. It explains why germination results can vary so widely between growers. Some will see fast, successful germination with warmth alone, while others experience much more reliable and even results after exposing seed to a period of chilling. Both outcomes are biologically correct and depend on the individual seed lot rather than grower error.
Reputable seed suppliers recognise this variability and account for it in their guidance. This is why cold stratification is often recommended as a precautionary step when sowing eucalyptus seed, as it removes uncertainty and improves consistency across different growing conditions.
How I Germinate Eucalyptus (The No-Heartache Method)
Eucalyptus seed can be unpredictable. Sometimes it germinates without cold, sometimes it doesn’t — and going back and forth moving seed trays into the fridge is frustrating and unnecessary. To avoid that entirely, I always pre-stratify the seed first, regardless of when I’m sowing.
Cold stratifying the seed before sowing removes dormancy in advance, meaning once it’s sown, it can stay put and get on with growing.
Step 1: Pre-Stratify the Seed (Always)
Before sowing, place the seed in the fridge for at least two weeks. This can be done dry in the packet or in a small sealed container. I do this even for autumn sowings — for example, chilling seed in September and sowing in October, November, or December. The same applies in spring: chilling the seed first avoids unreliable germination and saves time overall.
( We do this with our seeds for sale as much as possible so look out for the pink pre stratified stickers if you order from us)
Step 2: Sowing (Any Season)
Once pre-stratified, sow the seed as normal.
Surface sow the seed — do not bury it deeply — using a free-draining compost. Lightly cover with a fine layer of compost or vermiculite and keep the surface just moist. Place the pots somewhere bright and mild, a greenhouse or cold frame is ideal, and allow time for germination. Because the seed has already been chilled, they should germinate without the need to move trays in and out of cold conditions later.
This approach works whether you’re sowing in autumn for overwintering, or in late winter and spring under cover.
Light Requirements (Non-Negotiable)
Once germinated:
Seedlings require very bright light
Low light causes weak, leggy growth
A bright windowsill, greenhouse, or grow light is ideal
Eucalyptus does not tolerate shade well at any stage. Consistent, strong light is critical for developing sturdy plants with good form and vigour.
Temperature After Germination
After germination, eucalyptus seedlings grow most strongly when temperatures are kept above around 10–12 °C. Below this range, growth slows significantly, even if plants remain otherwise healthy.
While established eucalyptus can tolerate cooler conditions, young plants are noticeably more sensitive and should be protected from frost during their early stages.
Cold temperatures alone rarely kill healthy eucalyptus seedlings, but problems arise when cold is combined with excess moisture. Wet compost in cool conditions dramatically increases the risk of root damage and plant failure. Maintaining moderate warmth alongside free-draining compost is therefore essential for steady, reliable growth after germination.
Potting On & Root Sensitivity
Eucalyptus seedlings dislike root disturbance and perform best when sown into individual pots from the outset. This allows roots to develop without interruption and helps plants establish more quickly.
Potting on should only be done when necessary, rather than as a routine step. Repeated handling and unnecessary disturbance can slow growth and stress young plants. A steady progression into larger pots, only when roots have filled the available space, produces stronger, more resilient plants than frequent moving or fiddling.
Soil & Drainage (Critical)
Free-draining soil is essential when growing eucalyptus, particularly during the early stages of growth.
Eucalyptus plants tolerate poor or low-nutrient soils far better than wet or waterlogged conditions. Roots sitting in heavy, moisture-retentive compost are prone to failure, especially in cooler weather.
If you are working with heavy clay or dense composts, improving drainage with added grit or sharp sand is strongly recommended. Waterlogged roots are the most common cause of eucalyptus growing problems, and ensuring excess water can drain freely is far more important than feeding or enriching the soil.
Planting Out
Eucalyptus plants should be planted out by mid-summer to give them enough time to establish before cooler weather arrives. Choose a position in full sun, as light is essential for strong growth and good structure. Young plants benefit from shelter during their first season, particularly from strong or drying winds, which can stress newly planted roots.
A light mulch around the base of the plant can help protect roots and moderate soil conditions, especially during the first winter. Mulching should be kept shallow and free-draining, as eucalyptus prefers protection from cold rather than excess moisture around the roots.
Pruning & Growth Control
Eucalyptus is a fast-growing plant, and without management it can become large very quickly. Regular pruning or coppicing is the most effective way to keep plants compact and under control, particularly in gardens or smaller spaces.
One of the advantages of eucalyptus is that juvenile foliage regrows strongly after cutting, making it well suited to this kind of management.
Pruning is best carried out in late winter or early spring, before strong new growth begins. This timing encourages healthy regrowth and helps maintain the desired size and shape of the plant throughout the growing season.
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