Silver Drop is a forgiving plant once it has lots of sun, fast-draining soil, and a light hand with fertilizer. The round silver leaves that make it so popular, though, belong to a young plant, and the tree swaps them for long ones as it ages.1Plant Lust. Eucalyptus gunnii Good care is therefore less about keeping it alive than about keeping it young-looking, through pruning and the right winter plan.
Light, Soil and Water for a Healthy Silver Drop
Young plants carry small, round, waxy silver-blue leaves on upright stems. As the plant matures, the leaves lengthen into blue-green lance or egg shapes.2Plant Lust. Eucalyptus gunnii Some stems may carry a mix of round and longer leaves as the plant ages, an early sign it is heading toward its adult form.
Silver Drop grows best in full sun.3Plant Lust. Eucalyptus gunnii Pick the sunniest spot you have, since shade leads to leggy, less silver growth. Avoid low spots where water pools after rain, and leave room for a fast-growing plant even if you plan to cut it back.
For soil, eucalyptus seedlings grow better in slightly acidic potting mix, around pH 5.1 to 5.6, than in alkaline mix.4Scientia Horticulturae. Response of ornamental Eucalyptus from acidic and alkaline habitats to potting medium pH That holds even for species that grow wild on alkaline soils.5Scientia Horticulturae. Response of ornamental Eucalyptus from acidic and alkaline habitats to potting medium pH An ericaceous or standard peat-based mix works well, and there’s no need to add lime.
For its first one or two growing seasons, a new eucalyptus depends entirely on you for water.6Hardy Eucalyptus Blog. How to water a newly planted Eucalyptus correctly! Water deeply so the whole root area is soaked, not just with a quick splash. Push a finger into the soil, and water when it feels dry a finger’s depth down. Expect to water more often in hot, windy or dry spells. Drooping or crisping leaves tell you that you have fallen behind.
Once its roots are established, the plant becomes very drought tolerant, and established Silver Drop prefers to stay fairly dry in summer.7Hardy Eucalyptus Blog. How to water a newly planted Eucalyptus correctly!8Plant Lust. Eucalyptus gunnii Constantly wet soil invites root rot, covered below, so good drainage matters as much as the amount of water you give.
Will Silver Drop Survive Your Winter
Silver Drop is reliably hardy only to about USDA zone 9, where winter lows rarely drop below about 20°F (-7°C).9Pinetree Garden Seeds. Silver Drop Eucalyptus In most of the US, that means pots need to come indoors for winter, or you treat the plant as an annual and start fresh each year.10Pinetree Garden Seeds. Silver Drop Eucalyptus Garden plants can sometimes outlast their rating, but that’s a gamble rather than a plan.
To work out whether your winter is a problem, look up your USDA zone from your postal code and compare it with zone 9, rather than guessing from how cold a typical winter feels. A single unusually cold night can matter more than the average winter, so check the coldest temperatures you have seen in recent years. If your zone is colder than 9, plan from the start for a pot or a yearly restart.
To bring a pot indoors, move it in before the first hard frost. Give it the brightest window you have, ideally a south-facing one. Water less in winter, letting the top of the mix dry out between drinks. Some leaf drop as it adjusts is normal.
In borderline areas, a sheltered spot near a wall gives extra protection, and mulch around the base protects the roots through cold snaps. A plant killed back to the ground may resprout from the base in spring.
Growing Silver Drop in a Pot
In a pot, Silver Drop typically reaches about 3 feet tall.11Pinetree Garden Seeds. Silver Drop Eucalyptus Eucalyptus roots circle badly in smooth-walled pots and grow bags, so air-pruning pots, with holes in the sides, are better. They keep roots branching and foliage healthy.12Hardy Eucalyptus Blog. How to grow Eucalyptus in a pot and keep it alive This matters most if you plan to plant it in the ground later, since circled roots don’t anchor well.
Choose a pot only a size or two larger than the root ball, and make sure it has drainage holes. Disturb the roots as little as possible when moving the plant, and repot in spring when growth starts.
Pots dry out faster than ground, especially in summer sun. Water until it runs from the bottom, then let the excess drain. Never leave the pot standing in a saucer of water.
How Much to Feed Silver Drop
Eucalyptus are low-fertility plants that are sensitive to high phosphorus. Use a balanced, low-strength fertilizer only once or twice in spring and summer.13Bountiful Gardens. Eucalyptus cinerea
On the label, look for an even or low-phosphorus formula (the middle number is phosphorus). Dilute it to half strength or less, and skip bloom boosters, which are high in phosphorus.
Overfeeding shows up as soft, floppy, fast growth, leaf tip burn, or a crust on the potting mix. If you’ve overdone it, flush the pot with plain water.
Pruning to Keep It Small and Silver
Coppicing means cutting every stem down to a short permanent stump and letting the plant regrow from the base.14Gadenin. Pruning Eucalyptus: Coppicing for Silver Leaves and Controlling Size It produces a multi-stemmed bush with fresh new stems and the round juvenile leaves.15RHS Advice. Eucalyptus Pruning Guide Eucalyptus gunnii is one of the species that responds especially well.16RHS Advice. Eucalyptus Pruning Guide Cutting every year gives the smallest plant and the most reliably round leaves.17Gadenin. Pruning Eucalyptus: Coppicing for Silver Leaves and Controlling Size A two-year cycle gives longer stems for cutting, with some leaves starting to lengthen.18Gadenin. Pruning Eucalyptus: Coppicing for Silver Leaves and Controlling Size So choose yearly for a neat silver shrub, and every two years if you want long stems for vases.
Wait until the plant is established before the first hard cut. Cut in spring as growth begins, not before hard frost, using clean, sharp loppers or a saw. Cut each stem to a few inches above ground and leave the stump to resprout. New shoots appear from the stump within weeks in growing weather. Pollarding is the alternative: it stops the plant at a chosen height by cutting it back there.19RHS Advice. Eucalyptus Pruning Guide
Growing Silver Drop From Seed
Start seeds indoors 10 to 12 weeks before your last frost.20Pinetree Garden Seeds. Silver Drop Eucalyptus Use a shallow tray or small pots with drainage holes so excess water can escape. A fine, light seed-starting mix works better than heavy garden soil, which packs down and holds too much water. Moisten the mix before sowing rather than watering heavily afterward, which can wash the tiny seeds together. Some growers chill moist seed for weeks before sowing to improve germination, though it isn’t proven necessary.21University of Hawaiʻi at Mānoa College of Tropical Agriculture and Human Resources. Growing Eucalyptus from Seed
Sprinkle the seeds on the surface of the tray rather than burying them,22University of Hawaiʻi at Mānoa College of Tropical Agriculture and Human Resources. Growing Eucalyptus from Seed because they need light to germinate.23Pinetree Garden Seeds. Silver Drop Eucalyptus A very light covering of mix is acceptable and helps keep seed moist.24University of Hawaiʻi at Mānoa College of Tropical Agriculture and Human Resources. Growing Eucalyptus from Seed
Seeds sprout in about 14 to 21 days at 65 to 75°F.25Pinetree Garden Seeds. Silver Drop Eucalyptus They can sprout in 7 to 10 days at 75 to 80°F,26Johnny’s Selected Seeds. How to Grow Eucalyptus from Seed so a seedling heat mat speeds things up. Keep the mix consistently moist but not wet, and high humidity helps.27University of Hawaiʻi at Mānoa College of Tropical Agriculture and Human Resources. Growing Eucalyptus from Seed Water from below or mist, so seeds aren’t washed out of place.28Johnny’s Selected Seeds. How to Grow Eucalyptus from Seed
To keep humidity up, cover the tray with a clear lid or plastic. Lift the cover daily for air, and remove it once most seeds have sprouted.
Give seedlings bright light so they don’t stretch. Move them to individual pots when they have a few true leaves. Before planting out after frost, harden them off outdoors gradually over a week or so.
Pests and Diseases to Watch For
Psyllids are small sap-feeding insects whose young leave white waxy crusts or fluff on leaves.29Center for Invasive Species Research. Red Gum Lerp Psyllid Heavy infestations produce sticky honeydew that grows black sooty mold and causes distorted new leaves.30California Agriculture. Parasitoid wasp controls blue gum psyllid Severe feeding causes leaf drop, and repeated loss of leaves weakens trees.31Center for Invasive Species Research. Red Gum Lerp Psyllid
Inspect leaf undersides and new shoots regularly. Rub off or prune small infestations, and rinse honeydew and sooty mold off with water. Indoor plants are easier to keep clean by hand.
Root rot shows as wilting, yellowing leaves, stunted growth and reddish-brown cankers on stems.32Gardening Know How. Eucalyptus Tree Diseases: Tips On Treating Disease In Eucalyptus Well-drained soil and not overwatering are the best protection. Rot is hard to cure, so if you suspect it, repot into fresh mix and cut back watering. Powdery mildew shows as white powder on leaves and stems.33Gardening Know How. Eucalyptus Tree Diseases: Tips On Treating Disease In Eucalyptus Improve airflow and sun to discourage it, and remove badly affected stems.
Using and Preserving Cut Stems
Cut stems in the morning, when they are full of water. Strip lower leaves that would sit in liquid, and recut the stem ends at an angle before soaking. A coppiced plant gives a steady supply of fresh stems.
Fresh stems can go in plain water and will last a good while in a vase. Change the water when it clouds, and recut the ends occasionally to keep water uptake going.
Eucalyptus stems can be preserved by standing them in a glycerin and water solution, which they draw up.34HortTechnology. Optimizing Glycerin-to-water Ratios for Preserving Eucalyptus Foliage A mix of 1 part glycerin to 3 parts water, left for about 2 weeks, works best. Stronger solutions don’t give better results, and treated stems stay more flexible than untreated ones.35HortTechnology. Optimizing Glycerin-to-water Ratios for Preserving Eucalyptus Foliage
The leaves are aromatic, which is part of their appeal. Eucalyptus leaves and oil are toxic to pets, so keep oils and leaves out of their reach.