I recently wrote an article on raspberry plants with curled leaves and I was surprised that there wasn’t a lot of information out there for yellow leaves as well. Since there’s some overlap, I thought I’d made a quick article on yellow leaves and how to fix it too. Here’s what I found.
Raspberry plant leaves turn yellow (chlorosis) from over-watering, a lack of nutrients, transplant shock, and leaf curl disease. To avoid these, only water when the top 2-4 inches of soil is dry, apply compost and mulch, and apply fertilizer if desired. Manage aphids by spraying water or neem oil, or with ladybugs.
Let’s take a closer look at how to identify which condition your raspberry plant might have, and how to fix it.
Raspberry plants are deciduous, so it’s normal for their leaves to naturally turn red, yellow, and brown before dropping in the fall and winter. This is a survival strategy many plants adapted to successfully live in cooler, more temperate climates.
By shedding their leaves, the plants enter a dormant state—similar to a bear hibernating.
Typically, deciduous plants require chill hours to stay in dormancy (under 45ºF). Raspberry plants require around 800-1200 chill hours for proper dormancy, leading to better flowering and fruiting in the spring.
On the other hand, evergreen plants (such as citrus trees) keep their leaves year-round. These plants either developed other ways to survive the cold, or live in tropical climates (with little to no frost).
If your raspberry plant has yellow or brown leaves in the fall or winter, know that this is normal. However, leaves with yellow or brown spots are different and can indicate disease (more on this later).
However, what happens if your raspberry plant has yellow leaves in the spring or summer?
Over-watering is the most common reason raspberry plants get yellow leaves, and there are two types (depending on the soil’s drainage).
|Soil Drainage||Caused By||What It Does|
|Fast||Too sandy or rocky soil||Leaches nutrients from the soil|
|Poor||Clay or compacted soil||Pools water and drowns the plant’s roots (waterlogged)|
Too much water in fast-draining soil strips the nutrients from the soil by pushing them further down (also called leaching). On the other hand, over-watering with poor drainage creates waterlogged soil and stresses the plant. Both lead to yellow leaves.
Before addressing the soil’s drainage, let’s start with the ideal way to water raspberry plants.
The best way to water raspberry plants is to only water when the first 2-4 inches of soil is dry. I check this by pushing a finger into the soil. Make sure to soak the soil down to at least 2 feet as 90% of the roots are found at this depth.
If you’re unsure if your soil is draining too fast or too slow, consider doing a percolation test.
Here’s how to do a percolation test:
- Dig a 1-foot by 1-foot hole
- Put a yardstick in it and fill it with water
- After an hour, measure the amount of water drained on the yardstick
When digging a hole, make sure to dig outside of the drip line (canopy) of your plants to avoid damaging their shallow roots. Also, consider digging up to 3 holes around your property as there can be vastly different soil types depending on the location.
Ideally, the soil should drain at a rate of around 2 inches per hour. However, this is a guideline and not a rule, so don’t worry if yours is off. This test is primarily to determine if your soil drainage is excessively too fast or slow.
How To Fix Soil Drainage
Fortunately, the solution for poor and fast-draining soil is the same. Increase the organic matter (compost) of the soil! This is because organic matter both breaks up larger clumps of soil and retains the proper amount of moisture.
For example, every 1% increase in the soil’s richness leads to an additional 20,000 gallons of water held per acre.
I recommend applying 2 inches of compost every 1-2 months under your raspberry plant’s drip line.
Once your soil has proper drainage, apply 4-12 inches of mulch to reduce evaporation, regulate soil temperature, and prevent soil erosion. This also helps feed the raspberry plant.
If you’ve checked your watering and drainage, and it seems right, what do we look for next?
3. Lack of Nutrients
|Nutrient Deficiency||Leaf Symptom|
|Nitrogen||Entire leaf is pale or yellow|
|Iron||Dark green veins, rest of the leaf is yellowing|
|Manganese||Broadly pale leaves, foliage color looks mottled or smeared|
Raspberry plants that lack nutrients often get yellow leaves, with the most common deficiencies being nitrogen and iron.
Yellow leaves are often called Chlorosis, which is the lack of production of chlorophyll. Without the green pigment from chlorophyll, the plant has a harder time photosynthesizing and creating the energy (sugars) it needs to survive.
So, what’s the best way to fertilize raspberry plants?
Provide raspberries with either chemical fertilizers or compost. Apply fertilizer as directed or 2 inches of compost every 1-2 months.
While chemical fertilizers are good in the short-term, they often have long-term effects such as drying out the soil and killing off soil life, making it more difficult for the plant to survive.
Alternatively, compost provides more than enough nutrients for plants and builds the soil’s health—bringing other benefits such as increased nutrient uptake, water retention, and erosion prevention.
For this reason, many gardeners are finding that compost is replacing fertilizers.
Either one you choose, you can see which fertilizers and compost I recommend on my recommended fertilizer page.
Imbalanced Soil pH
Raspberry plants prefer a soil pH of 5.6-6.2.
While nutrients are essential, a balanced soil pH is needed for proper uptake. And like most plants, raspberries prefer a slightly acidic soil pH. This is because an acidic pH is required to dissolve the nutrient solids and make them accessible to the plant’s finer roots.
Fourteen of the seventeen essential plant nutrients are obtained from the soil. Before a nutrient can be used by plants it must be dissolved in the soil solution. Most minerals and nutrients are more soluble or available in acid soils than in neutral or slightly alkaline soils.Donald Bickelhaupt, SUNY College of Environmental Science and Forestry
The best ways to check your soil’s pH are with pH strips or a meter. I prefer using a pH meter since they’re easy to use and affordable. To see which pH meter I use and recommend, check out my recommended tools page.
If you find your raspberry’s soil pH is too acidic (below 5.6), apply alkaline amendments such as wood ash, biochar, or lime.
For soil that’s too alkaline (above 6.2), apply acidic amendments such as sand, peat moss, and coffee grounds.
4. Transplant Shock
If your raspberry plant was recently planted or repotted, and its leaves are starting to curl, yellow, or brown, it’s likely due to transplant shock. Transplant shock occurs when a plant is exposed to a new environment and has to establish a new root system.
Avoid transplanting raspberry plants unless necessary as it can take up to 1 year for recovery.
To help avoid transplant shock, I like to plant with the following steps in mind:
- Have the new ground (or pot) prepared
- Remove as much of the plant’s current topsoil as possible, without damaging the shallow roots
- Grab the base of the plant’s stem and wiggle lightly
- Using your other hand, scoop up and support the rootball
- Lightly place the plant in the new ground (or pot) and fill it in
- Make sure the soil is at the same level on the plant as before
- Apply 2 inches of compost and 4-12 inches of mulch to the top of the soil
- Water generously and add more soil as needed
5. Leaf Curl Disease (Aphids)
Aphids are small bugs that suck the sap from underneath the raspberry plant’s leaves. This loss of sugar and moisture causes the leaves to curl, yellow, and drop. They also cause raspberry leaf curl virus.
When aphids suck the plant’s sap, they deposit honeydew—which attracts ants. If left unchecked, aphids can damage the plant’s health and potentially stunt or kill it.
These bugs come in multiple colors including white, yellow, or black, and usually are found hiding underneath the leaves. Typically, aphids won’t cause damage to the fruit, but because they suck sap from the plant, they can compromise its health and therefore reduce fruit size and yield.
The best ways to get rid of aphids (and mites) on raspberry plants is by spraying the infected leaves with water or neem oil, or releasing ladybugs (a natural predator of aphids and mites). Most often, a jet of water is enough to knock them off and kill them, but neem oil is a good second option.
For example, when my potted Kaffir lime tree had aphids, I found that a jet of water was sufficient to blast them off and prevent them from coming back. All I did was remove the hose nozzle and used my thumb to increase the pressure. Just keep in mind that too strong of a blast can damage the leaves.
Other bugs can also cause leaf curl on raspberries, including:
To learn more about raspberry leaf virus, and the pests that cause raspberry leaves to curl, check out this Berry Diagnostic Tool by Cornell University.
Need More Help?
You can always ask us here at Couch to Homestead, but you should know the other resources available to you! Here are the resources we recommend.
- Local Cooperative Extension Services: While we do our best with these articles, sometimes knowledge from a local expert is needed! The USDA partnered with Universities to create these free agriculture extension services. Check out this list to see your local services.
- Permaculture Consultation: Need help with a bigger project? Send us a message.