If you want an uncommon, versatile fruit for your kitchen that’s practically impossible to find at the market, consider growing thimbleberries.
It’s easy to pass over thimbleberries as a growing option; they’re far from a common choice. They grow wild throughout parts of the United States, though you rarely see them in the grocery store or nursery.
But they’re delicious, packed with nutrients, and simple to grow.
What Are Thimbleberries?
Thimbleberries – Rubus parviflorus – are a native deciduous, thornless shrub that grows in the wild, typically found in disturbed sites along wooded hills and near streams. They pop up after brush fires, adapting and growing well in various soil types and sunlight availability.
Thimbleberry plants are relatives of blackberries and raspberries and grow in the Northwestern US from Alaska to California and even into Mexico’s northern range.
Thimbleberries are edible to humans as well as animals and provide habitats and food for wild animals.
The shrubs produce pretty white flowers followed by bright red, juicy fruits that pull from the plant, leaving behind the core. That gives the fruit the appearance of a thimble, which is how it received the name.
While resembling one, thimbleberries aren’t a berry but rather a drupe, coming from a group of druplets. The fruits fall apart easy, making it hard for commercial cultivation. That’s why you usually won’t see these in your local grocery store.
But despite the difficulty in harvesting, they’re wonderfully delicious, with a tart flavor, perfect for jams or as a topping for fish or chicken.
As more gardeners turn to permaculture practices, they discover all of the amazing edible fruit bushes that grow wild in the United States.
Instead of foraging them, try growing thimbleberries on your property to add more edible fruits that grow year after year.
Planting Thimbleberries in Your Garden
Let’s look at how you can grow these wild Rubus bushes in your backyard.
First, find a location that works best for a thimbleberry plant. They prefer to grow in full sunlight to partial shade. That means they need between four to eight hours of sunlight, with the latter providing optimal for growth.
Thimbleberry plants grow in a range of environments in the wild, so they handle almost any soil type. The most important requirement is to ensure the soil is well-draining; soggy roots kill Rubus bushes easily.
The best practice is to spread compost or composted manure where you’ll plant the bushes. Make sure to mix it well into the soil.
Starting Thimbleberries From Seed
While most gardeners prefer to buy bare-roots or potted thimbleberries, it’s possible to grow them from seeds.
Birds spread the seeds in the wild, so to start thimbleberry seeds, it’s essential to mimic this and use cold stratification and scarification to germinate the seeds.
When the seeds go through the bird’s digestive system, it damages the seed’s outer coating. To replicate this effect, use sandpaper or a small knife to damage the outer coat of the seeds.
We have a whole guide on this process, which is known as scarification, if you’ve never done it before.
Then, place them in a bag or jar and put them in the freezer for several months before planting outside. After that, it’s time to plant the seeds in six-inch containers. Put them in the ground when they’re 3-inches tall.
The process can be a bit of a pain, so most opt not to use this method. But if you’re up for the challenge, it’s a cheap and effective way to plant.
Plant with Plenty of Space
Assuming that you provide the bushes with nutrients and optimal lighting, these shrubs will grow large. They need – at least – three feet between each cane in a row. The rows should be spaced eight feet apart for proper air circulation.
After amending the soil, dig a hole that is two feet deep and three feet wide to accommodate roots. Small, bare-root plants need a much smaller hole.
Place the thimbleberry plant in the soil, gently spreading out the roots. Make sure the roots go in different directions to encourage proper root growth and establishment.
Fill the hole back in with loose dirt, cover the entire root ball, and press the soil down around the plant’s base firmly. Then, water thoroughly, saturating the soil. Doing so helps encourage the establishment of the roots.
Caring for Thimbleberry Plants
Once established, thimbleberries require little maintenance. They’re a wild plant that thrives in a range of conditions; little help is needed.
The soil needs to stay moist, especially during the months after planting, to encourage establishment. Drip irrigation is highly recommended during the fruit-bearing season, when dry soil could cause a lack of fruit production.
Mulch Around The Plant
Mulching is an essential step because it helps to retain moisture in the soil, which reduces how often you need to water the plants. Mulch also keeps the soil temperature even and keeps competing weeds away.
Spread an organic mulch around the bushes, keeping it off of the main trunk. Compost or grass clippings are fantastic options; grass clippings will decompose and provide a boost of nitrogen, which thimbleberries appreciate.
Prune for Ideal Production
An important practice to remember is to prune off the canes that have already fruited after the berry harvest. Doing so encourages more sunlight and air to reach the new canes that will form the following year.
Companion Plants for Thimbleberries
Since thimbleberries belong to the same family as raspberries and many other Rubus species, it’s safe to pick companion plants that work with those bushes.
Here are a few options:
Pests & Diseases That Might Cause Problems
Since most thimbleberries grow in the wild, they’re hardy against most pests and diseases. Here are a few that might cause problems.
Aphids are one of the most common garden pests; nearly everyone will encounter them. These tiny pests like to stick to the underside of leaves and suck out the sap while leaving a sticky residue called honeydew behind.
Most infestations are mild. Knock the aphids off of the plants with water. Bad infestations can be treated with insecticidal soap or an insecticide.
Crown borers have stout bodies, clear wings, and resemble a yellow jacket. They like to infest raspberries, but thimbleberries can be a victim as well. The larvae tunnel through the lower cane and cause the cane to wilt and break off.
Unfortunately, crown borers are hard to get rid of, so it’s recommended that you remove the plants to prevent the spread to other hosts in the area.
Yellow-Banded Sphinx Moth
Yellow-banded sphinx months look like adult bumblebees. They aren’t as common as other pests, but the larvae like to feed on thimbleberries.
It’s hard to control these because the larvae dig into the plants. The best route is to use an insecticide that’s formulated for moth larvae. If you see them, make sure to handpick them off and kill them in hot, soapy water.
Anthracnose is a fungal disease that causes dark lesions on the leaves. It can even lead to sunken lesions and cankers on the twigs and stems.
Prune off the infected branches to control the early stages of this disease. You also can use fungicides, but they’re not entirely effective. In bad cases, you might have to remove the plant because anthracnose can’t always be completely controlled.
To prevent, make sure to keep water off of the leaves. You can do this by watering at the soil level, and keeping plants well spaced and pruned.
One of the most widespread plant diseases is powdery mildew. It appears as patches or spots of white to grey, talcum-powder like growth that thrives in warm, dry climates.
Avoid applying fertilizer late in the season, because it encourages this disease. You can use chemicals to control an infestation if combined with control methods to reduce the spread.
Raspberry Leaf Spot
Raspberry leaf spot impacts most of the plants in the Rubus genus. It causes red or brown spots to form all over the leaves, which eventually turn gray. Eventually, the leaves curl and become dry.
Keep plants well spaced and appropriately pruned to help prevent the disease. Copper based fungicide can eliminate it.
It takes the new shoots two to three years to bear fruit. The fruit starts to ripen in late summer to early fall. They produce best in areas with cooler summers because hot temperatures stunt their growth.
It’s essential that you harvest thimbleberries quickly when they reach their peak ripeness. They attract a lot of wildlife who want to feed on the fruits. You’ll know when they’re ready because they’ll be plump and juicy, but the fruits are soft, so be careful while harvesting.
Don’t toss them into buckets; be gentle. Damaged fruits spoil quickly. While the best way to enjoy thimbleberries is fresh, try turning large crops into thimbleberry jam.
Because they have a tart flavor, they are delicious sweetened or used as an accent in savory dishes such as on fish, chicken, or pork.