(Almost) Anyone Can Grow Blueberries!


You probably already buy blueberries, so why not grow your own? Photo: http://www.almanac.com

Blueberries (Vaccinium spp.) are a fruit of North American origin, but are becoming more and more popular around the world. In addition to being delicious and sweet, blueberry fruits are excellent for your health. The blueberry is one of the temperate fruits richest in antioxidants thanks to the abundant anthocyanins it contains. It is also rich in vitamins C and K, not to mention a host of other minerals and vitamins.

Blueberry muffins are a favorite coffee shop snack. Photo: http://www.averiecooks.com

Blueberries were once very much a seasonal crop, but now, with blueberry farms being found in both hemispheres over a wide range of different climatic conditions, you can find fresh blueberries in supermarkets most of the year. If not, you can certainly find frozen blueberries in any season and also a wide range of blueberry products: muffins, yoghurt, jams, jellies, chocolate-covered blueberries and much more. 

And many people from Eastern North America, where blueberries are particularly numerous in nature, can fondly recall family trips into the wild to harvest blueberries as a child.

Finally, if you garden, there’s a very good chance you already grow your own blueberries, but if not, you can certainly do so. In fact, it’s not even particularly difficult.

In Which Garden?

Blueberries offer great fall color. Photo: garden.org

The classical way to grow blueberries is to plant them in the vegetable garden. After all, they are edible plants and fairly compact, right? But I’d like to encourage you to think of them in a new light: as edible plants that are also ornamental and to move them from the veggie bed into your home landscape. This fits in with the foodscaping trend that is all the rage these days and is so easy to do. 

A blueberry hedge. Photo: tcpermaculture.blogspot.com

The blueberry is the ideal plant for foodscaping. With its dense, shiny, dark green leaves, its beautiful little white to pinkish bell-shaped flowers in the spring, its attractive summer berries and its flamboyant red leaves in the fall, it has everything a landscape plant needs. And if planted in a row, it even makes an excellent privacy hedge.

Which Blueberry Should You Grow?

There are actually many species of blueberries, but there’s only one, the highbush blueberry (Vaccinium corymbosum), that is really widely grown and easy to find in almost any nursery. And it’s probably also the easiest one for most gardeners to grow.

Highbush blueberries have the largest fruit of any blueberry. Photo: http://www.amazon.com

The highbush blueberry is a medium-sized shrub, reaching 6 to 10 feet (1.8 to 3 m) if you let it grow on its own, but is usually kept to 3 to 4 feet (90 to 120 cm) high and wide in landscape situations with the help of a bit of judicious pruning. This is the blueberry you see in supermarkets, with big bluish berries. It’s best adapted to moderate climates: hardiness zones 4 to 8.

Lowbush blueberry. Photo: Σ64, Wikimedia Commons

The lowbush blueberry (V. angustifolium), native to the Northeastern United States and eastern Canada, is widely grown commercially, but not as easy to find in nurseries. Most blueberry farms growing lowbush blueberries actually count on wild plants, subtracting any competing vegetation so the wild plants can take over, although there are plenty of cultivars around that are more productive than the wild plants. Where you can find it in nurseries, it makes a great groundcover, many cultivars not reaching over 1 foot (30 cm) in height. Its fruits are small, but numerous and especially sweet. The lowbush blueberry is the hardiest of the commonly grown blueberries, adapted to zones 2 to 7.

Then there are the half-high blueberries, which as you probably guessed, are hybrids between highbush and lowbush blueberries. They’re intermediate in just about every way, from plant size (about 2 ½ feet/75 cm) to fruit size and even hardiness: zones 3 to 8. 

‘Biloxi’ is probably the most widely available southern highbush variety. Photo: backyardberryplants.com

All the above varieties need a long, cold winter, so gardeners in mild winter climates need to look elsewhere. Their best choice is probably the southern highbush blueberry, which is not a species, but was rather developed from crosses between the regular highbush blueberry (V. corymbosum) and such heat-tolerant southern blueberry species as evergreen blueberry (V. darrowii) and rabbiteye blueberry (V. virgatum; formerly V. ashei). Southern highbush blueberries are fairly new to the market and still rather hard to find, but, with their hardiness zone range of 7 to 9, they extend the range of where you can grow blueberries as far south as Northern Florida.

Another choice for mild climates is the rabbiteye blueberry (V. virgatum). It’s a tall blueberry easily reaching 10 feet (3 m) in height and likewise adapted to hardiness zones 7 to 9. 

The Secret Is in the Soil

The great secret of blueberry cultivation is to provide it with a light, acid soil, with a pH of 4.2 to 5.2. A pH of up to 6 is acceptable, but production may be reduced. This much more acid than most other crops and in fact, most other ornamental plants. Rhododendrons and azaleas are among the few garden plants commonly grown in soil that acid. 

That’s why the very first thing you should do if you want to grow blueberries is to have a soil test done. In some areas, soils are naturally acidic and no special treatment is required. Elsewhere, it may be necessary to add an acidifying soil amendment, such as garden sulfur or horticultural peat, to the soil to bring the pH down.

If your soil is not just “neutral” but out and out alkaline (a pH of over 7), it’s probably wiser to give up your plans of growing blueberries. It’s already very difficult to lower the pH of a naturally alkaline soil, but keeping it low is even more complicated. It will tend to creep back to its natural range. Another possibility is to grow your blueberries in containers using a naturally acid soil.

You need light, acidic soil to grow good blueberries. Photo: http://www.hgtv.com

Where the soil is light or sandy, blueberries will be very happy. And planting will be a snap. Just dig a hole (a trench if you’re planting a hedge) 2 to 4 inches (3 to 5 cm) deeper than the height of the root ball. By placing the root ball in a hole of that depth and covering the lower part of its stems with soil, that will encourage the plant to produce a better root system.

On the other hand, blueberries have a hard time dealing with heavy clay soils. If that’s the situation in your garden, the best thing is not to dig a hole and replace the old soil with an amended lighter one (that can lead to rot). Instead, it’s better to plant blueberry plants on a raised mound, bringing in a light, acidic soil from elsewhere for that purpose. A mound about 3 feet (1 m) wide and 18 inches (45 cm) high would be perfect.

You can also mix a slow-release, all-purpose fertilizer into the soil at planting. Avoid so-called starter fertilizers or transplant fertilizers: rather than helping plants root, they often hinder root production!

There is no need to add commercial mycorrhizal fungi to the soil at planting. Blueberries do not enter symbiosis with the type of mycorrhizae generally offered in commercial inoculants, but instead need a special kind: ericoid mycorrhizae. The blueberries that you will buy are probably already naturally inoculated, but if you’re concerned they might not be, add a shovel of soil taken at the foot of a rhododendron, azalea, blueberry or other ericaceous plant: it will undoubtedly contain the missing mycorrhizae.

Beyond Soil

Blueberry flowers are an attraction in their own right. Photo: mgnv.org

Even if blueberries can grow in partial shade, they’ll produce fewer flowers and therefore fewer berries. Full sun is usually best. Only in really hot climates with intense sun is partial shade the best choice. In colder climates, a sheltered location where snow accumulates is ideal.

Space highbush blueberries about 3 to 4 feet (90 to 120 cm) to give them enough space to grow while lowbush berries will make a nice groundcover if planted about 8 inches (20 cm) apart.

Few plants appreciate mulch as much as blueberries. Photo: parsolfarms.com

Water well after planting and keep the soil moist but not soggy afterwards. Always cover the soil with about 2 to 4 inches (5 to 10 cm) of mulch. Not only will that help maintain reasonable soil moisture, but it also largely eliminates the need to weed … and you don’t want to do any hoeing at the base of blueberries: they tend to produce a lot of very shallow roots and don’t appreciate disturbance. You can use the mulch of your choice: whatever is available locally at a reasonable price will do.

But what about the popular belief that pine needles make the best mulch for blueberries because they help acidify the soil? Well, pine needles really aren’t acidic. The belief that they are is an old myth that refuses to die. You can indeed use pine needles as mulch, but just don’t count on any acidifying action on their part.

It’s best not to let your blueberries produce the first year, or even the second if you started with very young plants. Wait until your blueberry plant is properly rooted before you let the plant bloom and produce delicious berries!

After a few years, starting pruning back older branches that are less productive so younger branches with better bearing potential have room to develop. You can do this in early spring. 

Fertilize annually, perhaps with an acidifying fertilizer.

Once your blueberry plants are established, you can expect them to produce for 20 years and more.

Choose the Right Cultivars

Most blueberries are at least partially self-fertile, but produce much more when they receive pollen from other blueberry varieties. Ideally, you’d plant not one, but two other blueberry varieties close together: that ensures the best cross-pollination. 

‘Bluecrop’ is one of the most widely available highbush blueberries. Photo: http://www.gardenia.net

There are dozens of cultivars in every category and some may perform better than others in different regions, so consult a local nursery for their suggestions. ‘Patriot’, ‘Northland’ and ‘Bluecrop’ are popular and generally easy to find highbush varieties adapted to a wide range of conditions. ‘Pink Lemonade’ is one of the new blueberries with pink fruits if that tickles your fancy, while ‘Perpetua’ produces two crops a year: one in early summer, the other in fall.

Sometimes nurseries offer “combo pots” with three varieties of blueberries growing in the same container. That can be an excellent choice for those who only have space for a single plant.

So, what are you waiting for? Plant a blueberry (or two or three) without delay!


No Summer Irrigation for Tulips


If you want to keep your tulips happy over the summer, don’t irrigate. Ill.: gallery.yopriceville.com & http://www.aquarion.com & http://www.sccpre.cat, montage: laidbackgardener.com

Did you know that irrigation systems and spring-flowering bulbs (tulips, hyacinths, crocuses, etc.) don’t always mix? During the summer, when these bulbs are dormant, they don’t need water and can rot if they receive too much. And even if they survive well-watered summers, their ability to bloom diminishes. That’s why you always find the most beautiful perennial tulips in flower beds that aren’t irrigated.

The narrow gray-green leaves of the botanical tulip Tulipa humilis are typical of arid climate bulbs and indicate that the species that really don’t appreciate well-watered summers. Photo: Softenpoche, Wikimedia Commons.

Some botanical tulips, such as T. hageriT. humilis andT. pulchella (T. humilis pulchella), have even more extreme needs and prefer near-desert conditions: hot summers with almost no rain. And yet, they love cold, snowy winters. Scorching hot, arid summers and cold, snowy winters? That’s not a combination all gardeners can offer! That’s why these xerophytic tulips behave like annuals in so many gardens.

It’s commonly said that botanical tulips tend to be more perennial that other tulips and there is certainly some truth to that, but to make that work, you have to mentally subtract from that equation the arid climate ones like T. hageriT. humilis and T. pulchella!

Daffodil bulbs don’t seem to mind irrigation in the slightest, even when they are fully dormant. Photo: http://www.saga.co.uk

If you do use an irrigation system to water your flower beds, that doesn’t mean you have to give up on all spring-flowering bulbs, because there are exceptions: bulbs that don’t mind moist conditions while they’re dormant. Daffodils (narcissus), alliums, camassias, chionodoxas, grape hyacinths, snowflakes, snowdrops and squills are among the bulbs grow well in irrigated flower beds, and often even proliferate there.

Even so, a true aficionado of spring-flowering bulbs would probably do best to keep summer irrigation to a minimum!

Bulk Up Baby Hostas… With Sun!


You’ve probably always heard that hostas are shade-loving plants, so the following tip is going to sound like heresy, but … if you want to get a young hosta, say a division from a larger plant or a small specimen of a large variety you’ve manage to buy on the cheap, to bulk up as quickly as possible, give it sun. Yes, six hours of sun a day if you can, most of it in the morning. Even full sun all day if you live in a cooler climate!

Do this in early spring as the leaves emerge or else in fall, when the growing season is over. In other words, at the time of year when you usually divide hostas. Don’t move a hosta division from deep shade to full sun in midsummer or all the foliage might burn off. (That won’t kill the plant, but it’s counterproductive, as it will slow the plant down while our goal is to speed it up.)

Sun Effects

Yep, this leaf has a bit of sunburn, but what’s left still carrying on photosynthesis… at a faster than normal rate. Photo: fiestafarms.ca

Bright sun may cause the leaves to bleach a bit and burnt patches to appear while blue hostas may lose the whitish bloom that gives them their color, but remember this is temporary. These damages only appear on the growth of the current year; the plant’s genetic traits won’t be altered. What the extra sun will do is to allow the leaves to absorb more energy and thus stimulate faster growth, as fast as that particular cultivar can handle (some hostas are naturally slower growers than others).

Of course, you can also plant young hostas in rich soil and keep them well watered. That too will help bulk them up.

Moving to Their New Home

When the hosta does reach the size you want, dig it up and move it to the deep shade if you want to (although hostas really are happiest in partial shade, not than anyone ever tells you that). It will hold its full size, even in soil filled with tree roots (i.e. dry shade), for years and years. But you do need to “plump up” young hostas first if you want to see them reach their full size within your lifetime.

The Moth That Flies Like a Hummingbird


Hummingbird hawk-moth (Macroglossum stellatarum) visiting a thistle. Video: gifer.com

One of the more curious insects you’re likely to run into as a gardener is the hawk moth, also called sphinx moth, a member of the Sphingidae family. There are over 1400 species found all over the world—big ones, medium ones, large ones—and what impresses most about them is their unique way of flying. Unlike the lazy movement of so many moths, they beat their narrow wings so rapidly, some up to 85 beats per second, that all you can see is a whir, often accompanied by a humming sound. This allows them to hover in the air, move forwards and backwards and travel at great speeds. Some are mistaken for hummingbirds! 

Hawk moth slowed down so you can see its movement. Photo: giphy.com

This hovering capability is only known to have evolved only four times in the animal world, always in nectar feeders: in hummingbirds, certain bats, hoverflies and hawk moths. It’s an example of convergent evolution. 

Hovering requires a huge amount of energy and indeed, hawk moths are heavy feeders, attracted to a specific sugary, energy-rich food: flower nectar. By hovering, they can gain access to flowers not available to other insects, often using a proboscis as long as or longer than their body to suck up the sweet liquid. 

Flowering tobacco (Nicotiana sylvestris) flowers droop scentlessly during the day, but rise up and give off a powerful perfume at night to attract their pollinator, the hawk moth. Photo: longwoodgardens.org

Some hawk moths are nocturnal or crepuscular, but others fly during the day, wowing gardeners with their acrobatics. For many plants, they’re important pollinators: many night-blooming plants give off heady aromas just to attract the nocturnal and crepuscular species. Think of flowering tobacco (Nicotiana sylvestris), a fairly popular annual, with its white, tubular blooms, wonderfully scented at night, but floppy and scentless during the day. 

The extraordinarily long spur of Darwin’s orchid means it can only be pollinated by a specific hawk moth. Photo: http://www.petrensorchidshop.eu

Indeed, for some plants, hawk moths are the only pollinator. The best-known case is that of Darwin’s orchid (Angraecum sesquipedale), whose white flower has a spur nearly 18 inches (45 cm) long that can only be pollinated by a specific hawk moth (Xanthopan morganii) with an equally long proboscis. The flower was discovered first, but Darwin accurately predicted that a corresponding moth would be discovered. You can read more about Darwin’s orchid and its pollinator here.

Behind Every Moth…

Yes, while the hawk moth may fascinate you and you certainly have nothing against its pollinating activities, you may have more trouble putting up with the caterpillar it arises from. Different species have different host plants (most are quite specific to certain plant species or families), but they all eat plants of some sort. 

Tomato hornworm (Manduca quinquemaculata): note the spike at the tip. Amanda Hill, Wikimedia Commons

The five-spotted hawk moth (Manduca quinquemaculata), for example, prefers tomatoes. Its larva is called the tomato hornworm. (Many hawk moth caterpillars have a spike at their tip and are thus called hornworms.) 

Eating people’s plants is not considered genteel behavior from a gardener’s point of view, so any hawk moth caterpillars spotted on a favorite plant (there is rarely more than one per plant) can be handpicked and disposed of or moved to a related plant of lesser value. 

Hawk moth caterpillars tend to be smooth and hairless and come in camouflage shades of green or brown. Some larvae are said to mimic snakes as a protective strategy. When resting, the caterpillar often bends its head down into a praying position, like the Great Sphinx of Giza, as in the photo above, whence the name “sphinx moth.” 

The caterpillars have a propensity for plants that are poisonous to other caterpillars, chewing on the soft new growth. Most then excrete the toxin, although some species retain it and become poisonous to their predators.

Hawk moths: fascinating creatures, aren’t they?

Touch-me-not Plants


Some plants have the ability to cause contact dermatitis (an unpleasant skin reaction).

Sometimes just simply brushing against the plant will do it, but in other cases, you actually have to bruise the plant or snap off a leaf or stem before a reaction will occur, because it’s contact with the sap that is harmful.

Note that in some cases, dermatitis will only occur if the skin is exposed first to the sap and then to the sun. This is called photodermatitis or phototoxicity. With these plants, there is therefore less risk of a reaction on a cloudy day.

Note too that sensitivity varies greatly from one individual to another: what can send one person to the hospital (and yes, that can happen!) may have no effect on another. But since you never know whether you’re sensitive or not, please wear gloves and long sleeves if you have to handle the following plants.

Buttercups* (Ranunculus spp.) can cause photodermatitis in sensitive individuals. Photo: pixbay.com
Dogbane (Apocynum androsaemifolium). Photo: Dcrjsr, Wikimedia Commons
Gas plant* (Dictamnus albus). Photo: http://www.specialplants.net 
Hogweeds* (Heracleum spp.). Photo: http://www.gardentags.com
Nettles (Uticaria spp. and Laportea spp.). Photo: Uwe H. Friese, Wikimedia Commons.
Poison-hemlock* (Conium maculatum). Photo: homeopathyonline.org.uk
Poison ivy (Toxicodendron radicans). Photo: meltonwiggins.com
Rue* (Ruta graveolens). Photo: http://www.qjure.com
Spurges (Euphorbia spp.). Photo: http://www.crocus.co.uk
Velvet bean (Mucuna pruriens). Photo: urbol.com
Wild Parsnip* (Pastinaca sativa). Photo: lcinvasives.org

*Plants causing photodermatitis.

How to Water Houseplants Over Summer Vacation


To keep your houseplants well watered during your summer vacation, move them back from the window and water them thoroughly, for once leaving water in their saucer. With a surplus of water and less intense light, they can easily go two weeks without watering.

Leaving for 3 weeks or even a month? Water them sparingly, move them well back from the window … and seal them in a clear plastic bag. This eliminates water loss due to transpiration. You can even leave them sealed like this for 6 to 8 months without fear for their health!

Succulent plants (cacti, crassulas, snake plants, etc.), however, won’t be happy sealed in a transparent bag (they won’t tolerate very humid air), but they use little water for their survival anyway. In their case, water well and move the plant back from any sunny window, but this time, without covering them with a plastic bag. In the open like that, they’ll lose more moisture to evaporation, but very slowly. Even after more than a month, they will still be in very good condition.

Adapted from an article originally published on July 14, 2014.

Quite the Caterpillar!


Question: My tree is full of caterpillars. Can you identify them? And what should I do about them? I suspect I’m too late, though. My tree has almost no leaves left and I’m pretty sure it’s a goner. 

Alex Arcand

Answer: Don’t give up too quickly! Your tree will probably be fine. But first, a word about this quite unusual-looking pest:

Your leaf eater is a red humpback caterpillar (Schizura concinna), a species that attacks a whole range of trees (maples, poplars, willows, elms, cherries, apple trees and many more). The female moth, an unobtrusive brown one that is rarely seen and only lives for a week or so in the spring, lays some 25 to 100 eggs under a leaf, which explains why you’re seeing so many caterpillars at once.

The red humpback caterpillar is strikingly colored: yellow lined with white and black with flanks dotted with black protrusions and double row of black spines along its back. The head is black in young specimens, but turns bright red later. And the most striking trait—the one which earned it its common name—the red hump behind its head, is most visible in the later stages of the caterpillar’s development.

Younger caterpillars are quite gregarious. Photo: Howell Curtis, http://www.butterfliesandmoths.org

These caterpillars are very gregarious at first and can be seen munching on a single leaf together, but later they become more independent and scatter over much of the tree.


A treatment with Btk at the right moment can kill the caterpillars. It’s harmless to other insects. Ill.: Thérèse Tourigny, from the book Les 1500 trucs du jardinier paresseux

Very often, by the time you notice the presence of these caterpillars, the damage is already pretty much done and little comes of treating them. On the other hand, if you catch the attack early in the season, while the tree still has enough intact foliage to be worth saving, you can control the caterpillars with an application of Btk (Bacillus thuringiensis kurstaki), a biological insecticide. After they have eaten the sprayed leaves, ingesting the Btk, it will make them sick and they’ll stop eating first, then they’ll die.

On the other hand, if you only notice the caterpillars at the end of the summer, watch how they react before you spray. If you can’t see them nibbling on leaves, they may have already stopped eating for the season. They do this in preparation for winter and shortly after will drop to the ground to pupate. And if they’ve stopped eating, Btk will be of no use.

There is only one cycle per year, at least in the temperate regions.

Hands Off!

Avoid touching these caterpillars. When they feel threatened, they emit jets of a smelly and irritating liquid to discourage predators. If it gets in your eyes, it’s not only painful, but can blind you temporarily.

Next Year?

Next spring, the pupae will give rise to winged moths that fly off looking for a suitable host for the next generation. The same tree is almost never attacked twice and indeed, the red humpback caterpillar is not something most gardeners see very often. This may well have been a once-in-a-lifetime experience!

Tree being defoliated by red humpback caterpillars. Photo: http://www.foothillpest.com

Of course, defoliation always looks very serious, leaving the tree with skeletonized leaves or even almost no leaves at all. In fact, though, it’s a fairly common occurrence in nature and trees adapt to it quite well. Your tree will soon produce new contingent of fresh leaves and … well, life just goes on. Unless defoliation occurs regularly on the same tree (unlikely with this pest, as mentioned) or it was already in bad shape for some reason, recovery is pretty much guaranteed. You might simply want to give it a bit more TLC next year to help its recovery: a bit of fertilizer, thorough waterings in case of drought, etc.

The red humpback caterpillar is strictly a North American insect, but there are different caterpillars all over the world with the same modus operandi that can be controlled in the same way.