Eucalyptus is a perennial: a woody evergreen tree or shrub that keeps its leaves all year and can live for decades where winters are mild. Many gardeners in cold regions still grow it as an annual and replace it each spring, because a hard winter kills it, not because its life naturally ends. The cold a eucalyptus can take varies so much between species that the right choice can mean a plant that comes back year after year.
What Kind of Plant Eucalyptus Is
Eucalyptus is a large group of more than 700 species in the myrtle family, the same family as myrtle and guava.1Wikipedia. Eucalyptus Most species are trees, many grow as mallees (several stems from one base), and a few are shrubs.2Wikipedia. Eucalyptus They grow upright and open, with long stems that branch only modestly.3NC State Extension Plants Database. Eucalyptus
The three words gardeners hear most are easy to mix up. A perennial lives more than two years, while an annual sprouts, flowers and dies in one season. Evergreen means the plant keeps its leaves through winter, which is a separate matter from lifespan. Eucalyptus is both, so widespread browning of leaves in winter signals stress, not normal rest.
A garden-centre eucalyptus looks nothing like a tree because it is a young plant that has not reached its mature size. Given years in a mild climate, many of these seedlings would grow into tall trees, which is why plant tags may list a height far greater than the pot suggests. A pot can hold a plant to a modest size for a few years by restricting its roots, but it does not turn a tree into a short-lived plant.
Will Eucalyptus Survive Winter Outdoors
Cold hardiness differs sharply between species. Roughly from least to most frost-hardy, the order runs mountain ash and flooded gum, then blue gum, then snow gum, then shining gum, with some alpine ash strains toughest.4Canadian Journal of Forest Research. Frost hardiness of commercial <i>Eucalyptus</i> species at different elevations Even within one species, trees from colder origins can handle more frost than others.5Canadian Journal of Forest Research. Frost hardiness of commercial <i>Eucalyptus</i> species at different elevations Blue gum, a common garden and cut-foliage type, sits in the middle of that range.6Canadian Journal of Forest Research. Frost hardiness of commercial <i>Eucalyptus</i> species at different elevations Cider gum, Eucalyptus gunnii, is widely sold as a hardier type for cooler gardens.7New York Botanical Garden LibAnswers. How do I care for a eucalyptus plant indoors?
Age matters too. A young plant with soft, unhardened growth is more vulnerable than an older one with woody stems, and a plant that has not had time to toughen up in autumn is at more risk from an early hard frost than one hardened by gradually cooling weather.
A frosted plant is not always dead. Many eucalypts recover by resprouting from a woody swelling at the base of the stem.8Forest Ecology and Management. Survival and recovery of Eucalyptus globulus seedlings from severe defoliation That swelling holds dormant buds and stored food reserves,9Forest Ecology and Management. Survival and recovery of Eucalyptus globulus seedlings from severe defoliation so a plant whose top dies in frost may send up new shoots from the base in spring. Plants grown from seed for one season may be too young to have built up much of that reserve.
Reading the damage takes patience. Browned or blackened leaves right after frost do not by themselves prove the stems or roots are dead. Damage often shows up days later, so wait before judging. Stems that stay flexible and green inside are alive, while brittle, dry stems that snap cleanly are likely dead, though the plant may still resprout from the base.
Wait until late spring before deciding the plant is lost, since new shoots can come late. Scratch the bark near the base: green tissue underneath means that part is alive. Once new growth shows, cut dead upper stems back to live wood or to the base. If no shoots appear by early summer, the plant has likely died.
To give an outdoor plant a better chance, plant it in a sheltered, sunny spot out of cold, drying winds. Choose a hardy species such as cider gum or snow gum rather than a tender one, and check your local hardiness zone against the species on the label before buying. Plant out early enough that the roots establish before the first frost.
Growing Eucalyptus as an Annual
Growers in cold zones such as 5B often treat eucalyptus as an annual, provided it is started early enough in the year.10Two Sisters Flower Farm. Can You Overwinter Eucalyptus Inside? How We Grow Eucalyptus in Zone 5B A seedling needs a long head start indoors to reach a useful size before autumn frost. Young eucalyptus leaves are usually rounder and broader than mature ones, and some types keep their young leaves longer.11Australian Journal of Botany. Leaf morphological and anatomical characteristics of heteroblastic Eucalyptus globulus ssp. globulus (Myrtaceae) The round, silvery foliage prized by florists and gardeners is often a feature of young plants, which suits a one-season crop.
Cut-foliage growers get a lot from this approach. Young plants supply those round, silvery leaves in quantity, and cutting stems through the season encourages branching, so regular harvesting can give you a fuller plant. Treating the plant as disposable also removes the hardest part of growing it in cold areas: keeping it alive over winter.
The timeline is simple. Sow seeds indoors in late winter so plants have months to grow. Indoor seedlings need strong light from a bright window or grow light, or they stretch and turn weak. Move seedlings outside after the last frost into full sun. Harvest stems through summer and early autumn for arrangements, and before the first hard frost, cut the remaining stems or bring the plant indoors.
If you want foliage for one summer, buying or sowing fresh each year is simplest. If you want a larger plant, overwinter it indoors or choose a hardy species.
Keeping Eucalyptus Alive Indoors Over Winter
Indoor eucalyptus needs strong direct light, ideally at least 6 hours of full sun from a south-facing window.12New York Botanical Garden LibAnswers. How do I care for a eucalyptus plant indoors? From November through February, keep it cooler, around 45 to 50°F (about 7 to 10°C).13New York Botanical Garden LibAnswers. How do I care for a eucalyptus plant indoors? During that rest, give very little water and no fertilizer.14New York Botanical Garden LibAnswers. How do I care for a eucalyptus plant indoors? Without this rest period, hardy types like cider gum lose their vigor.15New York Botanical Garden LibAnswers. How do I care for a eucalyptus plant indoors?
An unheated sunroom, enclosed porch or cool bright room often works. A warm living room near a radiator is usually too warm for the rest period. If a window gives less than 6 hours of sun, grow lights can make up the difference. Move the pot back outside in spring once frost danger passes.
Pot choice affects root health. Smooth-walled pots can make eucalyptus roots circle, which is bad news if you plan to plant it out later.16Hardy Eucalyptus Blog. How to grow Eucalyptus in a pot and keep it alive Pots designed to air-prune roots stop them at the edge and push new ones to form, which helps keep the plant healthy.17Hardy Eucalyptus Blog. How to grow Eucalyptus in a pot and keep it alive Use a well-draining potting mix.18The Spruce. How to Grow and Care for Eucalyptus
Bring the plant in before the first hard frost, but expect it to drop some leaves as it adjusts from outdoor to indoor light. Check leaves and stems for insects first so pests do not spread to your other houseplants. Cutting back on watering gradually as autumn cools helps the plant ease into its rest instead of being stopped abruptly.
Pale, stretched, leggy growth usually means too little light. Dropping or crisp leaves can mean dry heat or erratic watering, and yellowing with wet soil points to overwatering during the rest period.
Soil, Water and Feeding
Eucalyptus tolerates most soil types but needs good drainage.19The Spruce. How to Grow and Care for Eucalyptus Most species dislike waterlogged soil,20RHS Growing Guide. How to grow eucalyptus and a slightly acidic to neutral soil is best.21The Spruce. How to Grow and Care for Eucalyptus To test a spot before planting, dig a hole and fill it with water. If water is still standing after several hours, drainage is poor, and a raised bed or container is the safer choice in heavy, wet soil.
Roots go deep to find water. Young garden plants benefit from deep, occasional watering that encourages roots downward.
Right after planting, water deeply to settle the soil around the roots. After that, soak the soil less often rather than sprinkling daily. Once established, many plants need water only in long dry spells. Potted plants dry out faster and need checking more often.
Too much fertilizer can hurt. Young eucalyptus is sensitive to both too little and too much phosphorus, and either reduces growth.22PubMed Central. Silicon attenuates nutritional disorder of phosphorus in seedlings of Eucalyptus grandis × Eucalyptus urophylla Avoid heavy feeding with high-phosphorus fertilizers.
Where Not to Plant a Eucalyptus
Fire risk comes mainly from bark and litter. The shedding bark of gum species catches fire easily and carries flames up into the canopy, throwing embers.23National Park Service. Eucalyptus: A Complex Challenge Green blue gum leaves are only moderately flammable, and young leaves resist flaming well.24National Park Service. Eucalyptus: A Complex Challenge It is the buildup of dead, dry, oily leaves and debris that is especially flammable.25National Park Service. Eucalyptus: A Complex Challenge In wildfire areas, keep trees away from the house and clear litter regularly.
Roots can invade pipes. Eucalyptus over 4 m tall within 6 m of sewers were a common factor in root blockages, especially in older clay pipes.26Acta Horticulturae. Root Invasion of Sewer Pipes in Suburban Melbourne Roots seek moisture, so leaking or damaged pipes attract them, and the joints in old clay pipes are the usual weak point. If you don’t know where your sewer line runs, find out before planting a species that will become a large tree. Growing in a container avoids the underground problem entirely.
Leaf litter can hold back other plants. Eucalyptus leaves and litter release compounds that can stop seeds germinating and slow seedling growth,27American Midland Naturalist. The Allelopathic Effects of Eucalyptus camaldulensis and leaf extracts reduced the growth and yield of wheat in tests.28PubMed Central. Allelopathic effects of leaf extracts of Eucalyptus camaldulensis Dehnh. on morphological, physiological, and yield traits of Ethiopian wheat (Triticum durum L.) cultivars Seeds and seedlings may struggle in thick eucalyptus litter.
A seedling that looks harmless in a pot may be a species that grows into a large tree, so judge its eventual size before planting. Removing a big mature tree is costly and difficult, so choose the spot carefully.
There are hundreds of species, from big trees to small, compact forms. For small gardens and spots near buildings, choose a smaller or shrubby type. Varieties such as silver dollar and baby blue are popular for foliage. Read the mature height on the label, not just the pot size.
Is Eucalyptus Safe Around Pets
Risk depends on dose and form. Eucalyptus contains eucalyptol, a fragrant oil, and is listed as toxic to cats.29Pet Poison Helpline. Eucalyptus Is Toxic To Cats A few leaves or weak oil usually cause only mild nausea.30Pet Poison Helpline. Eucalyptus Is Toxic To Cats Concentrated essential oil, swallowed or on the skin, can cause severe nervous-system signs and, rarely, kidney harm.31Pet Poison Helpline. Eucalyptus Is Toxic To Cats Keep essential oils well away from pets, and call a vet or poison line if exposure happens.
A cat that chews a leaf may drool, vomit or seem unwell, usually soon after eating. A large amount of plant, or any amount eaten by a small animal, is more worrying than a nibble. To reduce risk, place potted plants where cats cannot chew them, pick up fallen leaves from indoor plants, and never apply eucalyptus oil to a pet’s fur or skin.
If your pet has eaten some, note how much and when, and take a sample of the plant or the product label to help the vet. Call a vet or animal poison line promptly rather than waiting for signs, especially if oil was involved. Don’t try to make the pet vomit unless a professional tells you to.
Preserving Cut Eucalyptus Stems
Fresh stems absorb glycerin through their cut ends.32HortTechnology. Optimizing Glycerin-to-water Ratios for Preserving Eucalyptus Foliage A solution of 25% glycerin and 75% water for 2 weeks worked best, and treated stems stayed more pliable than untreated ones.33HortTechnology. Optimizing Glycerin-to-water Ratios for Preserving Eucalyptus Foliage Preserved eucalyptus can last months or even years in arrangements.34American Floral Endowment. Discovering the Best Way to Preserve Eucalyptus Foliage
To do it at home, cut healthy stems and recut the ends before soaking. Mix one part glycerin with three parts warm water, and keep the stems standing in it for about 2 weeks.
Pick stems that look fresh and healthy, since glycerin preserves what is there and cannot revive tired foliage. Strip lower leaves that would sit under the liquid, because they may rot and spoil the solution. Recutting the ends at an angle gives the stem more surface to absorb it.