Vermont has maple syrup. Florida has oranges. Oregon has marionberries. Named for the Oregon county in which it was developed, marionberries are the result of cross-breeding ‘Chehalem’ and ‘Olallie’ blackberries. The final plant, which was released by the University of Oregon and the United States Department of Agriculture in the 1950’s, was the juicy, sweet-meets-tart ‘Marion’ blackberry, more commonly referred to as marionberry.
Oregon continues to champion the marionberry to this day, and as a result, this delicious caneberry is widely adored by commercial growers and home gardeners alike. In 2008, Oregon growers produced over 39 million pounds of blackberries, with marionberries accounting for two-thirds of that crop. The state of Oregon even designated marionberry pie as its official state pie in 2017.
The good news is that you don’t have to live in Oregon to enjoy growing (and consuming!) this beloved berry. Under the right conditions, marionberry is an easy-to-grow plant that thrives in the home garden.
Marionberry Overview
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What Is It?
Marionberries are a cane-producing perennial plant, along with raspberries and other blackberry hybrids. From their crown, they sprout thorn-covered, flexible, woody stems called canes, which will produce leaves, flowers, and fruit.
Marionberries, like other blackberries, have a unique growth habit. While the roots and crown are perennial, the leaf and fruit-bearing canes above are biennial.
Vegetative first-year canes (called “primocanes”) overwinter on the plant and then produce small white flowers, and subsequently, fruit in their second year. At this stage, they are called “floricanes”.
Floricanes flower in late spring, and the plump, aromatic berries that appear in mid July are highly sought after for their sweet, yet earthy-rich flavor. If not immediately gobbled up fresh, berries can be turned into jams, baked into pies and tarts, tossed into salads and cocktails, and even cooked into pork chops.
Planting
Marionberries are difficult to start from seed and are generally grown from a transplant or bare root. For both methods, wait until the threat of frost has passed in the spring, and the soil can be easily worked.
Transplanting
Planting a potted marionberry is easy! Dig a hole at least two times the size of the nursery pot. Carefully pop the plant out from its nursery pot and set it in the hole, ensuring that the root ball is level with the surrounding soil. Plants set too high in the ground may get heaved out during winter frost heaves, and plants buried too deeply may suffer from girdled stems and suffocation.
Now backfill. I prefer to push about half the soil back in the hole, water deeply with a hose to remove any hidden air pockets, then push the remaining soil in.
Give marionberries plenty of room to stretch their canes. Space individual plants 3-5 feet apart in rows that are at least 6 feet apart.
Bare Root Plants
Bare roots are just as they sound: a small section of stem or cane, with a clump of roots attached. They may not look like much, however, plenty of plants grow happily from a bare root planting, including fruit trees, roses, and yes, marionberries.
If you’ve received an order of bare root marionberries in the mail, you’ll want to unpack and plant them immediately. Store them somewhere cool and slightly humid – a refrigerator or basement will work – if you cannot plant them within a few days of their arrival. Soak the bare root in water for a few hours just prior to planting.
Time to dig! The hole should be wide enough to allow you to spread the roots out. Place the bare root in the planting hole, and then backfill, taking care to cover the roots evenly with soil. Roots exposed to air and sunlight will not survive for an extended period of time. Water the bare roots deeply to help settle the soil and push in any air pockets.
How to Grow
Marionberries are a little picky in terms of the proper growing environment, however they require very little maintenance aside from their yearly pruning. When planted in the proper location, these resilient cane-bearing plants will provide fresh fruit for years to come.
Light
Plant marionberries in full sun. These plants will tolerate partial shade, but gardeners will likely see fewer berries.
Water
Marionberries are thirsty plants, and gardeners should aim to give them 1-2 inches of water per week. These plants are decidedly not drought-tolerant, and they’ll need longer, more frequent watering during hot, dry periods. Overhead watering promotes fungal diseases, so consider installing drip irrigation to maximize efficiency and avoid soaking the upper leaves and stems.
Soil
Plant marionberries in loamy, well-drained soil that is high in organic matter. Add plenty of leaf mold or compost to the garden prior to planting. These plants also prefer slightly acidic soils, typically a pH of 5.6–6.5.
Marionberries can be grown in raised beds, which is a good choice if you have extremely poor native soil with little to no drainage. However, their expansive, trailing nature means they can take up space quickly. Plan ahead and make sure your raised bed is adequately sized.
Temperature and Humidity
Marionberries are particular when it comes to their growing climate. Hardy just in zones 6-9, these plants prefer mild, temperate conditions. They do not grow well in extreme heat or cold. True to their Pacific Northwest roots, marionberries will thrive in any region that has cool, wet winters and dry, mild, sunny summers.
Fertilizing
Marionberries are heavy feeders and require an annual dose of compost and fertilizer to stay healthy. Fertilize plants with a balanced, granular fertilizer in early spring, when new growth is just emerging.
Slow cane growth and pale, stunted leaves may be signs that the plant is nitrogen-deficient. Consider applying a nitrogen-based fertilizer about a month before harvest time if you notice these symptoms.
Trellising
As a type of trailing blackberry, marionberries can produce long canes that will drape on the ground if not properly supported. Train primocanes to a fence, a premade trellis, or even your own easy-to-build, DIY caneberry trellis.
Trellising this plant keeps canes off the ground, allows good airflow between the canes, and also provides a frame to throw a row cover over should exceptionally cold weather show up in the forecast.
Pruning
As with most cane fruits, marionberries will require regular pruning to encourage healthy air circulation and proper fruiting. In the first season after planting, no pruning is required, with the exception of any dead or diseased canes. Allow healthy canes to leaf out and the plant to generally get established.
The following year, and each year after, remove the spent floricanes in late summer or early fall, after fruits have been harvested. Prune floricanes at the very base of the plant; they will not produce another batch of berries. Take care not to accidentally cut the vegetative primocanes – remember, these will be covered in berries the following year!
After the spent floricanes are removed, you’ll have space on the trellis to gently ease this year’s primocanes up and off the ground. These will overwinter. It may seem confusing at first, but after a season or two, the cycle of trellising and pruning will come naturally.
Harvesting and Storage
Berries are typically ripe and ready for harvest in mid summer, between July and August. Marionberries will not continue to ripen once they’re off the plant, so be patient and wait for the berries to progress from a glossy black to a dull black color. Pick marionberries in the morning when the fruits are firm. Research suggests that you should avoid harvesting in the rain or when the fruits are wet, to prevent mold and rot.
Eat these sweet fruits fresh while you’re poking around the garden (which is my favorite way to eat berries!), or bring them inside. On the counter, marionberries will typically last just 1-2 days, while refrigerated berries may last 3-5 days. Do not wash berries until you are just about to eat them. Pop them in the fridge dry; moisture can cause mold to grow.
For tasty marionberries all year long, you’ll need to freeze them. I prefer to gently spread my berries across a cutting board and then place the cutting board in the freezer overnight. This helps to freeze each individual berry and prevents the giant lump of freezer-burned fruit that we’ve all experienced. Once individually frozen, berries can be stored in a freezer bag or storage container.
Common Problems
These vines are very resilient, but not totally immune to pests and diseases.
Pests
Birds and bugs are the biggest threats to ripening fruits.
Vertebrate Pests
Unfortunately for us, marionberries are as beloved by garden pests as they are by people. Birds, rabbits, and deer will happily harvest these berries before you’ve made it out to the garden. Physical barriers like netting or fencing are the best method of protection; no chemicals and no harm to the animal.
Cane Borers
Mature borers are clear-winged moths, however the immature larvae do most of the damage. Cane borers will tunnel through individual canes and part of the plant’s crown, severely weakening the plant. Prune and toss infected canes as soon as possible. Sawdust-like frass is a tell tale sign the larvae are present.
Japanese Beetles
These voracious foliage feeders will demolish the leaves off your roses, zinnias, raspberries, apple trees, and, yes—marionberries. If you catch them early, simply pick off the individual beetles and toss them into a bottle of soapy water. Again, a physical barrier may be the best protection here. Consider covering your berry canes with a row cover that will let in plenty of light and water but block the beetles.
If Japanese beetles have been a significant issue in the garden, prevent them with treatments of beneficial nematodes. For the most success, treat the soil ahead of the season in spring. Space two applications two weeks apart in temperatures between 50 and 80°F (10-27°C).
Aphids
Aphids are tiny sucking insects that feed on the undersides of leaves. They slowly drain the fluid from the plant, and leaves will curl and die. Aphids leave a sticky substance in their wake that attracts ants as well as different types of mold.
Start your treatment with a strong stream of water from a hose. Follow up with insecticidal soap sprayed on the infested leaves, or consider attracting beneficial predatory wasps or ladybeetles to keep the aphid population in check. Plant bonesets, yarrow, dill, and fennel nearby to host these insects. Many plants support beneficial predators. Do some research to see which are best for your garden.
Diseases
Pathogens thrive in humid areas with poor circulation.
Orange Rust
This fungus appears as a bright orange powder on the lower leaves, which eventually wither and die. Orange rust spores spread easily via the wind, and cool, wet conditions greatly exacerbate the infection. The fungus is systemic and will overwinter in the crown and canes of marionberries, so incidental pruning will not help.
Infected plants should be dug up and removed from the garden. Prevent orange rust by spacing individual plants at least 5-6 feet apart and thinning floricanes immediately after berry harvest to keep good air circulation between plants.
Cane Blight
Cane blight is caused by a common fungus that also causes stem canker on roses. Infected canes may have a dark brown infection line with dead shoots and leaves above that line. Cane blight is more prevalent on plants that are injured or improperly pruned.
Encourage adequate air circulation between plants by pruning and thinning regularly. Additionally, maintain healthy, nutrient-rich soil; underfed and under fertilized plants will produce weak canes that are more prone to breakage and less likely to fend off infection.
Anthracnose
Another fungal disease, anthracnose is characterized by brown spots with purple edges on infected leaves. Spots will eventually spread to stems and canes, causing dieback. Be sure to remove all infected marionberry leaves and stems from the garden to prevent this disease from overwintering. Do not compost the prunings. Instead, destroy them or throw them in the garbage.
Botrytis
Also known as gray mold, this fuzzy, pale gray layer will cover the berries themselves. Fruits are especially susceptible if there is overhead watering or long periods of warm, humid weather. Train trailing canes up off the ground and prune dead or old canes regularly to encourage adequate air circulation between fruits and leaves. Harvest ripe fruits as often as possible to prevent them from molding.
Frequently Asked Questions
Yes! Marionberries are a cultivated type of blackberry that you may also see written as ‘Marion’ blackberry.
No. Marionberry is a commercially cultivated type of berry that does not germinate easily from seed. Don’t confuse this plant with the Himalayan blackberry (Rubus armeniacus), a completely different species that arrived from Europe and spreads aggressively.
Nope! Marionberries are self-pollinating, meaning that just one plant alone will produce fruit.
