By Sheryl Normandeau
Illustration by Carol Trumbley
Goji berry (also called wolfberry) is a member of the Solanaceae family, which includes tender tomatoes and eggplants. Its medium green, lanceolate leaves grow in an alternating pattern, with each leaf about seven cm (3 in.) long. Attractive purple and white trumpet-shaped flowers appear in early summer, followed by fruit about four to six weeks later. Small (1.25 cm/0.5 in.) oblong berries appear in mid-summer. They must be left on the shrub to ripen to a bright red colour before harvesting, usually beginning in mid to late August. If the weather is damp and cool, fruit yield and quality will suffer—hot, arid conditions are ideal for a good harvest.
Goji shrubs are self-fertile and do not require cross-pollination: you’ll get fruit on a single plant. Depending on the cultivar, fruit production does not occur until the second or third year of growth, and then peaks around the fourth or fifth year.
Shrubs produce flowers over a long period of time, so the berries do not all appear at once. This makes for a less rushed harvest. The shrubs typically bear fruit up until frost. Handpicking is best for harvesting, but be gentle, as the berries are soft and may bruise if handled roughly.
Spring planting is ideal for goji shrubs, although the job can also be undertaken in early autumn. Do not plant if temperatures are too high, since it can result in transplant shock. Ensure the planting hole is at least two to three times the width of the root ball. There is no need to amend the planting hole. Mulching with an organic mulch, such as straw, leaves or a layer of compost, will help with moisture retention and stabilize soil temperatures.
To start goji berry shrubs from seed, use a dampened potting soil mix that contains perlite. Plant one seed per container, at a depth of about 1.25 cm (0.5 in.). Cover the container with a plastic dome lid or bag. The seeds should germinate in approximately three weeks. Do not overwater; it may increase the risk of rot or damping off.
Goji berry seedlings do not transplant easily and must be allowed to establish a strong root system before they are moved.
Training your goji
Goji shrubs reach a height and spread of 2.5–3 metres (8–10 ft.), but the upper limit of that size range can (and should) be controlled by a regular pruning schedule. Without a yearly trimming, goji shrubs have an unkempt, rambling habit. Your efforts will not only tidy the shrub’s flexible arching branches, but flower and fruit production will increase.
Since goji produces fruit on new wood, it is best to prune the shrubs in late winter while they are still dormant (diseased or dead branches can be removed at any time). Time your work so that the plants have not yet experienced bud break.
Do not prune your goji shrub in the first year. In the second year, single out the largest, strongest and healthiest branch as the main trunk. Trim off the lower lateral (horizontal side) branches. Keep in mind that the branches of your goji have thinly-spaced thorns, so be sure to wear gloves and protective clothes. As the shrub grows, you’ll want to leave the lower 35 cm (14 in.) of the trunk bare, so keep trimming those branches away. Prune annually by removing any branches that cross, then remove the growing tips of the side branches. Take out at least 15 cm (6 in.) of growth each time. You can remove more if the plant has grown too large to easily harvest fruit.
It sounds drastic, but pruning so much material from the tips of the branches will lead to a denser growth habit and potentially better fruit production—and you will be surprised at how quickly those lateral branches grow!
You can also grow goji shrubs along a trellis. It may be necessary to help the shrub climb by tying or pushing young branches through the trellis. An alternative is to gather together several strong stems and affix them to a stake. You’ll still need to prune your trellised or staked goji to keep the shrub to a manageable size.
Bear in mind that goji shrubs may sucker and reseed as they mature. If this is not desirable, be prepared to dig up or mow the suckers and seedlings down when they appear. Above all, locate shrubs appropriately. If you allow the suckering habit, goji shrubs make excellent fillers for large spaces and are effective on hillsides. They can also serve as hedging material, with edibility as a huge bonus. If you keep them under control, goji shrubs are ideal in most small spaces in your garden, as long as they have enough sunlight and air circulation (and you can easily reach to harvest fruit and prune).
Sun, soil and water
Allow a full sun location for maximum fruit production. Partial shade is acceptable, but yield may be affected. Goji shrubs are adaptable to most soil types, including clay, but cannot tolerate boggy conditions. They will not perform well in acidic soils; keep soil pH between 6.8 and 8.1.
While they do not require rich, fertile soil, a side dressing of compost or liquid kelp every spring is beneficial. Too much nitrogen will cause lush foliage growth, which will actually reduce the amount of sunlight getting through the crown to the fruit, minimizing yield and encouraging fungal diseases such as powdery mildew. This is one plant that doesn’t mind a little neglect!
Although they are tolerant of drought, ensuring the plants receive enough moisture within the first year or two of planting is critical to the establishment of a healthy root system. A drip irrigation system is ideal, but a good deep soaking at the base of the shrubs with a garden hose will work as well. Do not use a sprinkler system, as this will throw water into the foliage or onto the trunk.
The quality of drainage around the shrub will help dictate how often you irrigate: sandy soils may require more frequent additions of water, while clay soils will not.
Water new plantings once per week if conditions require it, and bear in mind that overwatering can contribute to fungal diseases and root rot. In years when rainfall is insufficient, some supplemental irrigation for mature shrubs may be beneficial, particularly during fruit production.
Weeds can inhibit the growth and success of your goji shrubs, so keep up with this part of your garden maintenance. Turfgrass may also compete unfavourably, so keep it out of planting wells.
A few common pests and diseases can affect your goji shrubs. Aphids are a possible problem. While they usually will not do significant damage to the shrub, aphids can reduce the leaf surface area, which affects photosynthesis and may diminish the plant’s overall health and production. Insecticidal soap can be effective against aphids if you find the balance tipped too far in their favour; if it’s only a mild infestation, treatment is not likely necessary.
Voles and mice sometimes chew on the base of trunks; installing a wire mesh tree guard, available at most garden centres, will address this problem.
Powdery mildew is another potential issue. It is best treated by ensuring the shrubs have proper air circulation (achieved through judicious pruning), as well as watering the base of the shrub instead of allowing the foliage to become wet. Much like their close kin, tomatoes, goji berry shrubs can be affected by blossom end rot, which causes a watery spot on the end of the fruit. This may not be entirely preventable, as it tends to occur with extreme changes in soil moisture brought on by weather. Monitor supplemental irrigation to ensure you are not overwatering.
Finally, birds love to eat ripe berries. You may need to use netting or time your harvest to beat them to the punch!
It can be difficult to track down different named cultivars of goji in Canadian nurseries, but availability is improving as demand increases. ‘Crimson Star’ is probably the most readily available cultivar for home gardeners, but other selections to look for are ‘Phoenix Tears’ and ‘Bountiful.’
Sheryl Normandeau is a Master Gardener and frequent contributor to The Gardener. Her articles and stories have appeared in several international publications. Follow her blog at FloweryProse.com.