Posted by Brent Wilson on 10/26/2016 to Fertilizing & Watering Tips
Raspberry bushes will benefit from fertilization, however, be careful not to over fertilize them.
How To Fertilize Raspberry Bushes
When to Fertilize Raspberry Bushes
At planting time, I mix composted organic matter in with the native soil removed from the planting hole and then mulch with compost, so there's no need for fertilizer. That said, you can fertilize plants 4-6 weeks after planting, with a timed- or slow-release fertilizer or organic plant food.
Beginning the second spring, I feed my established raspberry bushes before new growth begins to emerge in late winter or very early spring. Some gardeners like to apply a second dose of fertilizer after harvest to stimulate growth of new canes. Cease fertilization after June.
What Type of Fertilizer?
When it comes to feeding raspberry bushes you have several choices. Commercial fertilizers, organic plant foods, or compost. I feed mine with an organic plant food and also mulch around plants with compost.
If you're not concerned about organics, you can feed raspberry plants with a well-balanced commercial fertilizer such as 10-10-10 at a rate of 4 to 5 pounds of fertilizer per 100 feet of row. Uniformly broadcast the fertilizer in a 2 foot band. If you have just a few plants apply about 2 ounces of 10-10-10 spread uniformly around the plant.
If you don't want to use 10-10-10, you can feed raspberry plants with a water-soluble liquid fertilizer such as 20-20-20 or an organic plant food such as 10-2-8. Follow instructions on product label for application rates.
Note: No matter which fertilizer you choose, adding 1-2 inches of compost or well-rotted manure as a side dressing around each plant in spring will add nutrients your plants will appreciate.
Boron deficiency in raspberries can produce lower yields and smaller fruits. If you suspect your raspberry plants are suffering from a boron deficiency, a tissue test of your plants must be conducted. Find the nearest lab by contacting your local extension office or the agricultural department of a local university. If tests determine that your plants are suffering from a boron deficiency, boron additives are available at nurseries as a foliar spray. An application of boron when none is needed is detrimental to crop production. You must not add this nutrient to your plant unless you have first conducted a tissue test.
Soil pH is Important!
Raspberry plants grow best in a moderately acid to neutral soil ranging between 5.5 to 6.5 on the pH scale. Most average garden soils fall between a pH range of 6.0 to 7.0.
Testing Soil pH
Soil pH is a measurement of the alkalinity or acidity of soil and is measured on a scale of 1-14, with 7 as the neutral mark. Any measurement below 7 indicates acid soil conditions, and anything above 7 indicates alkaline. If you're unsure about the pH of your soil, or whether or not it is suitable for growing Raspberry plants, it's a good idea to test the pH in the planting area. You can quickly test soil pH with an inexpensive soil pH tester probe. To raise the pH (make more alkaline) you can add pelletized limestone to the soil. To lower the pH (make more acid) you can apply Soil Sulfur, Aluminum Sulfate, or Chelated Iron. Adding organic compost to the soil or using compost as mulch can also help to increase acidity and maintain acid soil conditions.
Learn More: What is Soil pH and How To Adjust It?
How To Water Raspberry Bushes
Raspberry plants prefer a consistently moist, but well-drained soil. Constantly soggy or wet soil can be problematic.
If you have just a few or several plants, hand watering is probably best. If you're growing a large number of plants in a row(s) consider installing a drip irrigation system.
Note: When fruits are on the plants, it's best to avoid splashing the foliage and berries with water, which can cause berries to rot. Avoid watering plants in the evening or at night. Water during the morning hours.
Immediately after planting deep soak the soil in the planting area, including the rootball, to a depth of at least 6 inches or equal to the height of the root ball.
During the First Active Growth Season
In average garden soil you should not have to water your new raspberry plants every day. More often than not, this causes soggy or wet soil conditions that can lead to root rot and other plant diseases. In the absence of sufficient rainfall, water only as needed to keep the root ball and surrounding soil moist. Keep in mind that deep soaking less frequently is much better than splashing just a little water on the plants every day. Plants planted during the winter dormant season, when plants are not actively growing and evaporation is much slower, will require much less water. So, be careful not to overwater during winter!
Tip: Apply a 1 to 2-inch layer of cured, shredded wood mulch or pine straw to help retain moisture and reduce hand watering. Avoid the use of freshly chipped wood mulch until it has cured in a pile for at least 6 months, a year is better.
When established, raspberry plants are fairly drought tolerant and will require less water, however will prefer a consistently moist soil when there is fruit on the plant. Lack of sufficient water just prior to and during the harvest season will seriously reduce yields and quality of fruit. This will not only affect the current year's harvest but also the following year's crop as the water shortage will limit the production of desirable fruiting canes called "primocanes." Keep plants mulched well to help retain moisture.
Plant Long & Prosper!™
Questions? Contact Us!