Everything About Marionberries: The Complete Guide

Marionberries or Marion blackberries, sometimes also known as “Cabernet of Blackberries,” are one of the best blackberries used in almost everything, including jam, juices, baked goods, and even in yogurt, due to their attractive deep reddish purple coloration, rich flavor and a texture that is superior to other blackberry varieties.

Since marionberries are so intense in taste, attractive to look at, and so highly prolific, it's rather hard to resist the temptation of growing one's own marionberries.

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What are Marionberries?

Marionberry plants are actually crossbreeds of two hybrids – the small yet delicious Chehalem blackberry (which itself is based on blackberry, Loganberry, and raspberry) and the larger, highly productive Ollalieberry.

Marionberries obtain the very best of the two crossed varieties with plump juiciness, intense flavor, and high amounts of nutrients in the form of vitamin C, rutin, and gallic acid, antioxidants that aid in circulation and are supposed to be great anti-cancer agents.

Marionberries also have a high fiber content and low-calorie count, i.e., only 65 to 80 calories per cup. The efforts for producing this berry started in 1945 by Oregon State University researcher George F. Waldo from the U.S. Department of Agriculture under its Agricultural Research Service program, and it was tested in the Willamette Valley.

Later it was released for cultivation in 1956 and was named after Marion County in Oregon.

The Willamette Valley in Oregon is considered the Marionberry Capitol of the world because of its perfect climatic conditions to grow these plants and fruits.

The warm daytime weather and cool nights are ideal for producing sweet, plump berries. 90% of the world’s production of marionberries takes place near Salem, Oregon. Marionberries are the single most cultivated blackberry in Oregon, with up to thirty million pounds of berries produced yearly.

Marionberry plants are extremely prolific and can produce up to 6 tons of berries per acre.

When compared to other blackberry cultivars, marionberries are medium-sized, around an inch in length, and conical in shape.

They are formed of clusters of drupelets or single seed-filled sacks surrounding a solid core.

Marionberries have a complex, slightly tart flavor - they are larger in size, sweeter, and juicier than the Evergreen blackberry or Himalayan blackberry.

More than 95% of berries are processed into frozen fruit, juice, and puree.

Ice creams, jams, and other products made using marionberries are popular in Oregon and also across North America.

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Marionberry Pedigree: Marionberries vs. Blackberries

Out of the two hybrid parents of Marionberries, the Chehalem berry is a cross between the Santiam blackberry and the Himalayan blackberry. The Santiam is a cross between a Loganberry and a native pacific blackberry.

On the other hand, Olallieberry is a cross between Loganberry and Youngberry, both of which are again caneberry hybrids.

While Loganberry is a cross between the raspberry and the native blackberry, the Youngberry is a cross between Loganberry and the native pacific blackberry.

Marionberry contains 44% Rubus ursinus (the only native blackberry in Oregon, known for its exceptional flavor), 25% R. armeniacus (the Himalaya, a weed that arrived in the late 1800s from Europe), and 6% R. idaeus (the red raspberry).

Generally, one can say that Marionberries are a variety of Blackberries, but Marionberries:

  • have much longer canes/vines,
  • don't have as  deep-black color as Blackberries,
  • have a firmer texture,
  • personally, Marionberries have better taste than typical Blackberry - slightly sweeter and slightly less tart flavor.

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Marionberry Plant

Marion is a vigorously growing, thorny plant that is characteristically trained to a two-wire trellis.

The plant is sensitive to winter cold, and yield may vary every year as per the severity of the weather. Marion is typically harvested in July by machines that shake the ripe fruit gently off the plants.

Do Marionberries have thorns?

Although Marion produces fruit of exceptional quality for processing, the plant is thorny, and when it is machine-harvested, thorns can enter the product, which can result in poor product quality.

Therefore, a basic priority of the breeding program has been to develop cultivars that don’t have thorns, are machine-harvestable, and still retain the outstanding processing qualities of Marion.

Thus, three thornless blackberry cultivars having these characteristics have been developed so far - they are Black Diamond, Black Pearl, and Nightfall.

Getting Marionberry Plants

Marionberries can be grown from seeds, but that requires time and effort, and in the end, one never knows exactly how the new plant will look like. Not to mention the size and flavor of the berries.

This can happen very often when Marionberries come from small gardens where they were grown near other plants from the same family.

Thus, if You really want to grow Marionberries, consider getting certified, disease-free, Marionberry plants from local garden centers or online shops.

Marionberries can also be grown using cuttings, air-layering, or by rooting the bent branch directly in the soil - unlike growing from the seeds, these methods ensure genetically the same plant.

How to Grow Marionberries?

Since marionberries are so intense in taste, attractive to look at, and so highly prolific, it's rather hard to resist the temptation of growing their own marionberries.

Marionberries, unlike most blackberries, is not bush but trailing vine, with most plantings producing only a few vines or canes. Marionberry canes can grow very long, up to 20 feet, producing many fruiting branches along their length.

Technically marionberries belong to the rose family, and they feature thorns that are much sharper and more densely packed than the rose thorns.

Therefore one should wear a long-sleeved shirt, leather gloves, and long pants while working with the plants.

It’s important to note that marionberries ripen through spring and early summer. Production reaches a peak during July and ends in early August. While growing for home use, the berries should be hand-picked, preferably early in the morning.

Planting the Marionberries

Marionberries should be grown on a site that receives full exposure to the sun without any standing water. The plants can tolerate shade but thrive best in full sun, at least for 7-8 hours per day. The soil should be well-drained, and its pH should be slightly acidic.

Before planting, one should prepare the bed by digging in and turning the soil to a depth of 10-12 inches. Any debris should be removed, and the ground should be as level as possible.

Adding good organic manure, peat moss, potting soil, worm castings, or compost in the soil during the autumn benefits the crop by improving soil texture and drainage.

If the soil is very heavy or has bad water drainage, marionberries should be grown in raised beds or even large containers.

The Marionberry plants should be planted in the early spring, an inch up from the base, but the crown of the plant should not be covered. The hole should be at least double the size of the root ball. The soil should be tamped around the plant firmly, and the plant should be watered well.

There should be a distance of 3-4 feet between plants and 6 feet between rows.

The plants must be supported with a stake and wire trellises to protect them from wind damage and for easy harvest. Each pair of stakes should be placed 4-5 feet apart with 2-3 stiff wires looped between. One of the wires should hang 5 feet high and the other 18 inches lower than the first one.

Watering the Marionberries

The plant should be thoroughly watered so that any air pockets around the root ball are filled.

Then the soil may be mulched with 2-3 inches of compost of pine needles which will retain moisture and prevent weed growth.

All through the growing season, the plants should be watered well, particularly during dry periods.

During this season, the plants require around 1-2 inches of water per week. It’s ideal to water with a water dripping system that delivers water at the soil level at low pressure.

If overhead sprinklers are used for watering, watering should be done early in the day so that the foliage gets time to dry off before evening to minimize the spread of disease. The soil should be kept moist but not saturated.

If red raspberries are planted in the garden, marionberries should be planted 100 feet away from them to prevent or at least minimize cross-pollination.

Fertilizing the Marionberries

When growing marionberries at home, it is recommended to fertilize the plants with dry manure pellets, worm castings and/or organic compost, which will decompose for months, gradually releasing the nutrients and keeping optimal pH levels. Such manure is added early in the spring and in the late autumn.

Balanced NPK fertilizers with gradual release may be added early in the spring and again during summer.

Marionberries require sufficient amounts of nitrogen fertilizer to grow well.

If required, 2 pounds of urea fertilizer should be spread per 100 feet of row in spring as new growth emerges. Most new growth will emerge from the plant’s crown below the soil.

A second application of 2 pounds of urea fertilizer should be added in June. A lot of energy is used by plants in spring when growth starts, so the plants should not be let dry out. Small yellow or pale leaves typically indicate a nitrogen deficiency.

How to Prune the Marionberries

Pruning should never be done during the first year except removing wood that is damaged, dead or diseased.

Every spring, depending on the plant's strength, growing conditions, and Marionberry variety, 5-10 of the most vigorous new canes should be chosen, and all other new canes should be removed - these one-year-old canes will bear fruit next year.

After canes fruit in their second summer, they should be immediately removed since they will never bear fruits again.

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Controlling The Weeds

During the growing season of marionberries, weeds should be kept under control because they will compete with the plants for water, nutrients, and space. Weeds can be controlled by using mulch to prevent their seeds from sprouting.

Mulch should be added every year as required.

Harvest and Preservation

The fruiting season of Marionberries is in summer, i.e., July, August, or September.

When berries are on the plant, they are very glossy and have dark, dark-red, black color.

Fruit will not ripen once it’s picked, so one should wait before picking until it’s fully ripe. Although upon ripening, the red fruit will turn black, it should not be picked immediately after it turns black.

One should wait for 3-4 days and should pick the berries when the color becomes a bit dull. Such fruit will be the sweetest. It should be picked in the morning or evening when the temperature is the coolest.

Home-grown berries should be stored in the refrigerator in a shallow container immediately after picking. Before storing, they should be washed and allowed to dry on a clean paper towel.

Fresh Marionberries can last for a day or two. But they may be frozen or used for pies, jams, syrups, and similar.

Harvest can be expected to be at least twice per week for many weeks.

Marionberry plants can be damaged easily, so they should be handled carefully. Plants should be protected from strong winds, and the plants should be winterized by covering them with straw or similar material to protect them from frost damage.

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Protection from Pests and Diseases

Marionberries plant is easy and vigorous plants to grow and, as mentioned earlier, yield an excellent harvest. But, they are also susceptible to leaf and cane spotting. So, fungicide treatment should be given.

Certified, disease-free plants should be bought from a reputable nursery. The plants should not be planted near strawberries, raspberries, peppers, and tomatoes because these plants can have and spread the same diseases.

Also, growing wild or any similar berries near Marionberries is not recommended, as they all share the same diseases and compete for water and nutrients.

Note: growing several Marionberries next to other berries in home gardens is totally another story ...

Common Pests and Diseases

Orange Rust

This is a fungus that causes plants to become weak and stunted with poor fruit production. Just after new growth is seen in spring, new shoots are gangly and weak, and leaves are pale green to yellow. Just in a few weeks, leaves’ lower surfaces are covered by powdery spores, which are bright orange in color.

Affected leaves wane and die by early summer. This disease is systemic and spreads throughout the plant. Hence only removing leaves cannot improve the plant’s health.

In this case, the infected plants should be dug up and removed and the adjacent wild brambles should be destroyed. If possible, the plants should be removed before the spores are discharged.

Crown Gall

In this disease, wart-like rough growths or galls are seen on the crown at or just below the soil surface. They can also appear on canes or stems, and then plants can be stunted and are subject to wind damage and drought stress. If the galls are large enough, they may cause girdling, which leads to plant death.

The canes should be carefully examined before planting to check if there is any sign of galls. An injury to the plant should be avoided. A small enough gall can be removed by cutting around it till healthy wood and allowing that area to dry out. If the plant is severely infected, it should be removed.

Anthracnose

Anthracnose is a fungus that causes spots on the canes with purple borders. The spots can spread and cover the stem. They may be seen on young leaves in the form of yellow spots with purple borders and may cause holes in the leaves. Due to this, canes and stems may die. In such a case, the infected canes and any leaf debris should be removed and destroyed.

Aphids

Aphids are peach-colored, black, red, or greenish-sucking insects that can spread disease while feeding on the undersides of leaves. They leave a sticky residue behind on the leaves that attracts ants.

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In such a condition, natural predators should be introduced in one’s garden, such as wasps or ladybugs who feed on aphids. They can also be washed off with a strong spray or an insecticidal soap.

Powdery Mildew

This appears in humid weather conditions on the top of the leaves. Leaves in such a condition have a greyish or whitish surface and may curl. Powdery mildew can be avoided by providing good air circulation to plants through decent spacing and pruning.

Phytophthora Root Rot

This is a soil-borne disease that arises in poorly drained soils and can live there for years. Its above-ground symptoms include small leaves, pale or reddish leaves, dying branches, defoliation, stunting, and ultimately death. In this case, the infected plant should be removed.

Leafhoppers

Leafhoppers occur in various shades of brown, yellow, and green and are extremely active, slender, and wedge-shaped. They can cause leaves to turn pale and curled and leave secretions behind on plants and fruit and can spread disease.

Japanese Beetles

These should be handpicked early in the morning into a bucket of soapy water.

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Borers

Larvae of borers are 1-inch-long worms with whitish bodies and brown heads, while adults are clear-winged moths with yellow and black bands on their bodies.

Larvae tunnel in canes and destroy lateral growth and cause canes to die. In such a case, the infested canes should be pruned and destroyed.

Spider Mites

These are very small spider-like pests that are about the size of a grain of pepper. They may be yellow, brown, black, or red and suck on plant juices, remove chlorophyll and inject toxins that cause white spots on leaves.

Their webbing is often visible on plants. They make the foliage turn yellow and become dry and flecked.

They flourish in dry conditions and multiply quickly. Spider mites can be controlled with a strong spray every other day. An insecticidal soap or hot pepper wax should be tried.

Birds

Marionberries are delicious and great tasting, not only to humans but also to birds. During harvesting season, the biggest issue may be birds - in such situations, the best option is to protect the plants with protective nets that will prevent the birds from reaching your berries.


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Long Story Short: Marionberries are easy to grow and take care of, and highly recommended for home gardens, just don't forget that they grow one year canes up to 20 feet in length. Thornless varieties are highly recommended, although common varieties can even be used for fences and walls.

Marionberries bear very tasty fruits, but they are also very decorative plants, especially during the flowering season. During a long harvest, feel free to enjoy fresh Marionberries.

Also, Marionberries can be frozen and used later, or they can be processed in jams, syrups, or one can make pies, etc.


For more information about Marionberries, feel free to check the following:

Growing Marionberries in Pots and Containers

marionberries in pot mMarionberries can be grown in pots and containers easily, but managing their long canes can be challenging.

Nonetheless, if You wish to grow Marionberries in a pot or container in your own garden, give them a try. They are easy to grow, have a long harvesting season, and fruits are sweeter and less tart than the fruits of classic blackberries.

Published: February 1, 2023.