Pint-size citrus; gardeners everywhere can find room for these dwarf trees - Garden and Outdoor Living

Sunset, Dec, 2003 by Lauren Bonar Swezey

For nearly 300 years, the mild-winter West has had a love affair with citrus. Orchards carpet the land in parts of California, and oranges, lemons, limes, and other citrus are familiar trees in home gardens.

Until fairly recently, most of these trees were robust growers, reaching 20 to 30 feet tall and as wide--too big for small gardens and certainly too big for most pots. Even semidwarf trees, introduced in the mid-1900s, grow 10 to 15 feet tall.

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Now dwarf citrus trees that grow slower than standards--reaching 5 to 7 feet tall in 13 years in the ground and staying even shorter in containers--are becoming more widely available. What makes them so compact are their roots. Sold as "dwarf" or "genetic dwarf," these citrus trees are grafted onto a rootstock called Flying Dragon--a naturally dwarf, contorted form of trifoliate orange (Poncirus trifoliata)--which reduces their height by 75 percent. But fruits are standard size, all within easy reach at harvest time.

Nurseries now offer an array of citrus trees on this dwarfing rootstock, from 'Washington' navel orange and 'Lisbon' lemon to 'Pixie' mandarin and 'Oroblanco' grapefruit-pummelo hybrid. In the mildest climates, shop for trees this month; in slightly colder climates, your best selection is in spring. In Sunset Western Garden Book climate zones 1-7, which are outside the citrus-growing range, you can buy a tree by mail and keep it indoors until after last frost. A good mail-order source is Clifton's Nursery (www.buyplantsonline.com or 888/209-4356; does not deliver to Arizona).

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Is it really a dwarf?

Nursery labels can be confusing. Some trees marked "true dwarf" are actually semidwarfs. But citrus grown on Flying Dragon rootstock are labeled as such by Monrovia and C & M wholesale nurseries; Willits & Newcomb wholesale nursery identifies its Flying Dragon citrus with a sticker on the label that just says "dwarf." If in doubt, ask your nursery whether the plant is growing on Flying Dragon.

Citrus care

Location: Choose a site that gets at least six hours of full sun per day and is protected from wind. In cool or foggy climates, locate the tree where it gets reflected heat from a sunny south-facing wall or driveway.

Drainage: Before planting citrus in the ground, make sure the soil is well drained. If your soil is compacted or of heavy clay and drains slowly, plant citrus in raised beds or containers. To improve water retention in sandy soils, dig in a 4- to 6- inch layer of compost to a depth of about 1 foot.

Mulch: Citrus tend to have shallow roots; adding a layer of mulch on top of the soil helps keep them cooler and reduces moisture loss from the soil. Apply a 2- to 3-inch layer of compost or other organic amendment under the tree's canopy, keeping it away from the trunk.

Fertilizer: Citrus grown on Flying Dragon rootstock are sensitive to highly alkaline soils (pH 7 and above). As long as the tree is fed regularly, such soils shouldn't be a problem. Use a fertilizer labeled for citrus; besides nitrogen, phosphorous, and potassium, it should contain the minor nutrients iron, manganese, and zinc. Follow package directions for application rate. If the foliage turns chlorotic (indicated by yellow leaves with green veins), spray it with a foliar food containing chelated iron and the minor nutrients listed above. Withhold fertilizer from fall through midwinter.

Watering: Drip irrigation is the most reliable way to keep citrus watered, particularly if it's growing in a container. Run the system often enough to keep the soil moist but not soggy. (For plants in the ground, water when the soil is starting to dry out 5 to 6 inches below the surface; in containers, when it's starting to dry 1 to 2 inches down.) Whether you water by drip or by hose, water long enough to moisten the entire root area. Consistent irrigation is key; fluctuating soil moisture can cause fruit splitting, especially of navel oranges.

Frost protection: When frost is predicted, make sure trees are well watered ahead of time. Wrap the tree with a string of Christmas lights, then cover it with a frost blanket or floating row cover (available from Harmony Farm Supply & Nursery, www.harmonyfarm.com or 707/823-9125).

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Pruning: Prune in late spring or summer to shape trees. Remove suckers that form below the graft union (denoted by a scar on the lower trunk). In the desert, fruit and trunks are susceptible to sunburn; allow tree canopies to grow low and full to provide shade.

Harvest: Most citrus fruits ripen from late fall into winter; exceptions are 'Valencia' orange, which ripens into spring and summer, and lemons and limes, which can bear year-round. Allow fruits to ripen on the tree. To determine whether sweet fruits like oranges are ready to harvest, pluck, slice, and taste one first. Pick lemons and other tart fruits before they become puffy.

Pest control: Aphids, scale, or spider mites may infest a tree, especially if it's weak from poor growing conditions. To control them, spray thoroughly (including cracks and crevices) with horticultural oil or insecticidal soap. (Scale are most susceptible to pesticides at the crawler stage, in midspring and mid- to late summer.)