Blueberries

Berries, birds, and cicadas in 2021

Maryland Grows3 Comments

For me, at least, it’s been a bumper year for berries.

Black raspberries in my garden in mid-June

In some years, I harvest only sparsely from the various fruit plantings in my landscape. Black raspberries, in particular, get snatched by birds before I can get to them. Not this year. I had them all to myself until this week, and they’re now pretty much done anyway. My guess—and I haven’t seen any science to back this up, but it makes sense—is that the birds have been too busy scarfing down cicadas to bother with berries. Now that the cicadas are gone, they may turn their attention to my fruit-bearing bushes, but I’ve had a head start.

Periodical cicadas are not an unqualified blessing for fruit growers, of course. Female cicadas lay their eggs in branches of a certain diameter, which are abundant on a lot of fruiting plants. This can cause dieback at the ends of these branches. The affected branch tips will fall off naturally over time; you can prune them if they bother you, but remember that cicada eggs are inside slits in the branches, and won’t hatch until probably August. I’m just going to leave mine alone.

Below you can see dieback on blueberry and pawpaw plants caused by cicada laying.

I didn’t bother covering most of my fruit plants, but here in Germantown we didn’t have a huge number of cicadas, either, so the damage has been minimal and the plants will recover. Some growers used netting to keep the bugs out, which is of course really inconvenient if the plants fruit during the same period. I was startled a number of times while harvesting when I moved a branch and suddenly encountered staring red eyes. The cicadas found my blueberries early on, as you can see by this nymph exoskeleton still clinging to a berry that ripened underneath it.

But they are not competition for the fruit itself, and since the birds have been ignoring the berries for the most part, my freezer is full of blueberries, black raspberries, and blackcurrants. I’ve made blueberry chutney, blueberry syrup, and blueberry-lavender shrub (from this book). Shrubs are refreshing drinks made from fruit, sugar, and vinegar, ready in a week or less to be enjoyed mixed with sparkling water or in various alcoholic and nonalcoholic blends. I have plans for jam, cassis and other alcoholic infusions, baked goods, and more.

Fruit-bearing shrubs and trees fit into a home landscape very well. Raspberries and blueberries are great starter plants; I also recommend currants for a shadier spot, though you will not be eating them fresh off the plant, so add in some processing time in addition to harvesting time. (Also be sure that you buy varieties resistant to white pine blister rust, for which the currant family is a host.) Pawpaws are wonderful native trees that add dramatic flair to a landscape; you need at least two genetically-different trees for cross-pollination. They will take several years to start bearing, depending on the size of the trees you plant, and mature trees do sucker prolifically, so you will end up with a pawpaw grove that needs some maintenance to keep under control. But the fruit is not commonly available for sale commercially, and it has a great banana-mango flavor that’s unusual in our temperate climate. You can also try blackberries, gooseberries, and figs. All of these are easier to grow in our climate than tree fruits like apples, peaches, and pears, but if you like a challenge, those are possibilities as well. You can find advice on all sorts of fruit growing on the HGIC website.

I’m wondering how next year will go in my fruit-growing adventure. All these cicada-stuffed birds are laying more eggs and raising more youngsters this year, so the population will be higher in 2022, and there won’t be any periodical cicadas to fill their bellies. So I expect I’ll have to be more vigilant about protecting the plants I can protect in order to have much of a harvest. But I’ll probably still have some leftover blueberries in the freezer, and plenty of jars of jam and chutney. Every year is different in gardening, and 2021 will definitely stand out in my memory for noisy cicadas, happy birds, and plentiful berries.

By Erica Smith, Montgomery County Master Gardener. Read more posts by Erica.

Blueberry success is all in the soil

Maryland Grows4 Comments

Farmers and gardeners learn much by daily tending soils and plants. But the winter “off-season” affords us time to dig deeper into topics of interest and learn from co-cultivators and experts in the field. I spent some time in a variety of grower meetings, conferences, and webinars in January and February where research findings were shared. Many gardeners are interested in growing blueberry so in this article I’ll share tips for success including some insights I picked up from presentations by Oregon blueberry researchers David Bryla, Ph.D. (USDA) and Bernadine Strik, Ph.D. (Oregon State U.)

Blueberry background

Highbush blueberry plants evolved to grow in low pH, high organic matter sandy soils with high water tables. These soils contain more ammonium nitrogen than nitrate nitrogen, hence blueberry’s preference for the ammonium form of plant-available nitrogen. The shallow, fibrous root system grows almost entirely in the top 12 inches of soil. Most of the roots are very fine, the width of a human hair, and can’t penetrate or thrive in clayey, compacted soils. The key to success is create garden conditions that mimic those in blueberry’s natural environment.

Blueberry thrives in well-drained, porous soils, high in organic matter (4% – 20%). The soil pH should be in the 4.5-5.5 range.

Soil preparation starts in fall

  • Begin by testing the soil in the late summer or fall prior to spring planting. For gardeners, soil testing labs provide the most accurate pH measurement of your soil, as well as baseline information on organic matter and nutrient levels. pH probes sold to gardeners are generally inaccurate and pH color kits using litmus paper are only accurate to ½ of a pH unit (5.5, 6.0, 6.5, 7.0, etc.

Add organic matter

  • The top 12 inches of soil should be one-third to one-half organic matter by volume. Peat moss (3.0-4.5 pH), plant-based compost (7.0-7.5 pH), and lightweight potting soil, a.k.a. soilless growing media (5.5-6.5 pH) are the materials most often mixed into the soil. Research has shown that adding compost (especially animal manure compost) can increase soil pH.
  • Some Oregon growers incorporate 2-3 inches of aged softwood sawdust into topsoil prior to planting. The benefit is that sawdust has a low pH, decomposes slowly, and increases organic matter levels. For Maryland gardeners, large amounts of sawdust are difficult to come by, but bark fines are readily available. You would need to apply 1.0 lb. of additional ammonium sulfate (21-0-0) per 100 sq. ft. nitrogen for the soil microbes that slowly decompose the bark fines.

Lower soil pH

  • Elemental sulfur is applied (based on soil test results) in the fall prior to spring planting, and incorporated to a 6-8 inch depth.
  • Pelletized and prilled forms of sulfur are easier to apply than powdered sulfur but take longer to lower soil pH.
  • An oxidation process, driven by special soil bacteria, converts the sulfur to sulfuric acid, releasing hydrogen ions that lower soil pH. The bacteria are most active in warm, moist soils. The process takes 6-12 months. Iron sulfate can also be used to lower soil pH but 6 times as much is required, increasing the cost.
  • Re-test soil pH to monitor pH levels and apply sulfur as needed to maintain the 4.5-5.5 range.
  • For container blueberry plants, mix 3 TBS. of sulfur into the top few inches of growing media, for a 15-gallon container, to reduce the pH by one unit (e.g. from 7.0 to 6.0).

Bag of sulfur
Elemental sulfur is available in powdered and pelleted forms

Fertilizing

  • Ammonium sulfate fertilizer is recommended because it supplies nitrogen in the ammonium form and helps acidify the soil.
  • Fertilize at full bloom and again three weeks later.
  • Urea is another good nitrogen source, recommended when soil pH is below 5.0 because it is only one-half as acidifying as ammonium sulfate. The nitrogen in urea is converted to ammonia and then to ammonium.
  • Oregon research studies show that feathermeal (12-1-0.5) and soluble fish fertilizers (4-1-5) work well in organic blueberry production. Organic growers prefer to inject fertilizers into irrigation water, known as “fertigation.” Another interesting finding was that there were no significant yield differences between the lowest (20 lbs./acre) and highest (240 lbs./acre) nitrogen fertilization rates.
  • Organic matter and organic fertilizers release ammonium ions with relatively little oxidized to the nitrate form as long as soil pH is in the 4.5-5.5 range. When soil pH is >6.0 most of the nitrogen from decomposing organic matter will be converted to the nitrate form with negative effects on plant growth.
  • Oregon research indicates that organic acids (humic and fulvic) applied in liquid form, increase blueberry root growth while lowering soil pH.

Developing blueberries
Blueberry fruits developing

Watering

  • Blueberry root systems need to be kept moist. Plants can tolerate hot weather but not drought. Water your blueberry bed thoroughly and consistently when rainfall is lacking. Soaker hoses and drip irrigation work well.
  • Blueberry grows and produces best when the pH of irrigation water is <7.0. Commercial growers often acidify irrigation water to maintain low soil pH. The pH of municipal water in our region is typically 7.5-7.8 and has a high salts and bicarbonate content. Just be aware that your irrigation water can drive up soil pH.

Blueberry plants in large fabric bags
Blueberry plants in large fabric bags

Mulching

  • Blueberry roots cannot compete very well with weeds for nutrients and water. Mulch is essential to keep soil cool, improve water infiltration, conserve soil moisture, reduce weeds, and increase organic matter.
  • Use aged wood chips (never fresh), shredded bark, pine needles, or sawdust as a mulch. These materials are low in pH (4.5-5.2) and salts, and decompose slowly.
  • Interestingly, a recommended growing system in Oregon uses strips of heavy-duty weed barrier to cover beds after they have been mulched to further reduce weed growth and moisture loss.

A well-planned and maintained blueberry bed can produce well for 20+ years. Start yours in 2021!

Resources:

Lowering Soil pH for Horticulture Crops. Purdue Extension

Organic Blueberry Research– eorganic.org

Author: Jon Traunfeld, Extension Specialist

Kent’s blueberry cage

Maryland Grows9 Comments

a row of blueberry shrubs protected by homemade cages

Some people like to keep birds in cages. Kent Phillips, a Master Gardener in Howard County, likes to keep birds out of his cage.

Each June, Kent and two helpers assemble a 10’ high by 10’ wide by 60’ long cage around his blueberry patch so the Phillips family, not neighborhood birds, will feast on the 16 to 20 gallons of fruit that his nine high bush blueberry bushes produce from early June into early August.

kent with blueberries

The uprights of the cage consist of 10-foot lengths of ¾-inch PVC pipe. Each upright is strengthened by a 10’ piece of rebar. Cross-supports at the top link everything together with a system of PVC T’s and L’s. Some are glued permanently, while others aren’t, to facilitate assembling the cage in spring and taking it down in the fall. He pounds a 3-foot piece of one-inch iron pipe into the ground to make 12” to 18” holes into which he slips the PVC/rebar uprights. He then wraps the huge, rectangular PVC box in plastic bird netting.

“I started out 20 years ago with a wooden structure,” Kent explained, “but that was frustrating because the bird netting snagged on every splinter. After a couple of years, I switched to PVC pipe. I use plastic ties to attach the netting to the PVC pipes.”

Kent estimated it takes about 2 ½ hours to put up the structure. “But all the work is worth it,” he said. “I have six varieties of early, mid-season, and late blueberries that produce over 6 to 7 weeks. Harvest depends somewhat on the weather.”

Kent listed three important factors to keep in mind when raising blueberries—pH of the soil, water, and the every-hungry birds.

a handful of blueberries

“The cage takes care of the birds, of course” he said. “My drip irrigation system takes about 3 hours a week to put down an inch of water, without which the berries would be stunted and production would fall. The Home and Garden Information Center has outlined a program using ferrous sulfate and elemental sulfur to keep the pH of the soil between 4.5 and 5.5, the range for maximum fruiting.

“We’ve been picking since early June,” Kent added. “This morning my grandson and my two daughters picked a couple of gallons and cleaned me out.”

What does his family do with up to 20 gallons of blueberries?

“We eat about half fresh and freeze the rest for later use,” he said with a smile. “Our wintertime favorites are blueberry muffins, blueberry pancakes, and blueberry buckle. They’re hard to beat.”

“I’m sure,” I replied, salivating at the thought.