Citrus japonica
Kumquat
Common names: Dwarf Orange, Oval Kumquat
At a glance
- Light
- Full sun
- Hardiness
- Cold damage below −6 °C
- Harvest
- Jan, Feb, Dec
- Spacing
- 200 cm, rows 200 cm
- Water need
- Medium
Photo: Public Domain · Source
This description was machine-translated.
Description
The kumquat is the most frost‑hardy citrus plant and remains a small ornamental tree especially suitable for balconies. Its small, oval fruits are eaten whole, including the sweet, aromatic rind, while the flesh is slightly tart. It blooms in summer and bears fruit abundantly through winter. In the DACH region it overwinters in a bright, cool location and tolerates brief, mild frosts.
Care instructions
Plant the kumquat outdoors in full sun and sheltered from wind from mid‑May (week 20). Water evenly with low‑alkalinity water and fertilize with citrus fertilizer from April to September. Overwinter it in a bright spot at 5 to 12 °C and water sparingly thereafter. Prune lightly in spring (March, week 11) to keep the tree bushy and compact.
The care notes were machine-translated from German.
Garden year
HarvestJan–Feb, Dec
Soil & site
Soil pH
Soil type
humus-rich, well-drained, sandy, lime-avoiding
Give the kumquat a slightly acidic, low-lime substrate: humus-rich, free-draining container plant compost into which you mix plenty of coarse sand or pumice so that water drains quickly. It cannot tolerate waterlogging at all. In the long term, water with low-lime water, otherwise the pH rises over the years and leaves turn yellow.
Feeding
Heavy feeder
Months
Apr–Sep
Feed in spring, when the plant comes out of winter quarters and sprouts anew: work mature compost and horn shavings shallowly into the top layer of soil. As a heavy feeder, the kumquat needs regular top-ups during the growing season from April to August via organic liquid feed in the water. From September, cut feeding back markedly and stop entirely before moving it into winter quarters.
Overwintering
From October, bring the kumquat into winter quarters before the first frost, bright and cool at about 5 to 10 °C, for example a stairwell, an unheated conservatory or a frost-free garage with a window. Water only sparingly in winter, gradually acclimatise it to the outdoors again from mid-April, and put it fully in the sun only after the Ice Saints.
Propagation
Methods
- From seed
- Cuttings
- Grafting
- Layering
Kumquats can be propagated in four ways, with grafting being the most reliable method for true-to-type fruit.
Grafting (spring): Cut a healthy scion from the variety you want and graft it onto a vigorous citrus rootstock (e.g. Poncirus trifoliata or bitter orange) with a cleft or bark graft. Bind the cut surfaces airtight with grafting tape. This gives you true-to-type fruit and the first flowers after only about two years.
Air layering (spring to early summer): Choose a one-year-old branch at least as thick as a pencil. Remove a ring of bark about 2 to 3 cm wide, lay moist sphagnum moss over it and wrap everything airtight in cling film. Keep the moss moist; after about 4 to 8 weeks, roots are visible. Then cut the branch off below the roots and pot it.
Cuttings (early summer, June to July): Cut semi-hardwood shoots 10 to 15 cm long with at least two pairs of leaves. Insert them in a mix of sand and seed compost, keep the soil evenly moist and put the pots in a bright but not sunny place at a warm temperature (around 22 to 25 °C) and high humidity (e.g. a polytunnel or cling film as a dome). Rooting takes several weeks to months and does not always succeed.
Sowing (March to April): Take fresh seeds from ripe fruits, let them dry for a day or two and sow them about 2 cm deep in seed compost. Keep them moist at 20 to 25 °C. Note: plants raised from seed are often not true to type and only flower after about 4 to 5 years.
Companion planting
Companion planting is partly traditional gardening lore. Where the reason is known, it is given.
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