Narrow Trees for Small Spaces


There are a thousand and one good reasons to plant a tree (they clean the air, prevent erosion, create refreshing shade, etc.), but only one not to: lack of space! City lots, by definition, are small and nowadays, even suburban lots are more and more limited in size. Should we therefore stop planting trees? Of course not! And there is even a category of trees that is well suited for use in narrow areas: columnar trees. 

Also called fastigiate trees, they don’t grow the way a tree normally would in the wild. The original species would probably have the rather rounded habit and spreading branches typical of your average tree. But occasional mutations occur that result in specimens with branches that, rather than stretching out more or less horizontally, grow upright, forming an acute angle to the trunk. This results in a very narrow habit and therefore a tree that can grow without difficulty in small spaces.

When such mutations are noticed by attentive horticulturists, they can be multiplied on a large scale and thus become readily available in nurseries.

Here are some examples:

Parkland Pillar® Japanese White Birch
(Betula platyphylla ‘Jefpark’)

Betula platyphylla ‘Jefpark’. Photo:

This birch combines very white bark with a very narrow habit. In addition, the foliage, dark green in the summer, becomes a beautiful yellow in the fall. It grows rapidly and reaches about 30 feet (10 m) in height, but only 6 feet (2 m) in diameter. It’s fairly resistant to bronze birch borer and seems completely resistant to Japanese beetles, unlike North American and European white birches. Plant it in full sun or partial shade in moderately moist soil. Hardiness zones: 2a to 7.

Columnar Crabapple
(Malus spp.)

Malus × adstringens ‘Durleo’ (Gladiator). Photo:

There are quite a few ornamental crabapples with a columnar habit. That means you can pretty much pick any combination of features – white, pink or red flowers, green or purple leaves, red, green or yellow fruit – and expect to find a match or two on the market. And there are columnar fruiting apples, too, that is, with large, edible fruits, for those who want to create a small urban orchard. Here are some varieties among the dozens that are available:

Malus ‘Maypole’ produces pink flowers, slightly reddish leaves in spring that turn green in summer and purple in fall, and small red fruits. M. baccata ‘Erecta’ (‘Columnaris’) is an old variety very easy to find in nurseries. It produces pinkish buds, white flowers and small yellow-red fruits over green leaves. M. ‘Gladiator’ (M. × adstringens ‘Durleo’) produces dark purple leaves, pink flowers and purple red berries. It’s extremely hardy (zone 2). And ‘Northpole’ is a fruiting variety, offering white flowers followed by red apples of good size that taste much like ‘McIntosh’ apples.

Columnar crabapple and apple trees are relatively short (rarely more than 13 to 16 feet/4 or 5 m) and most are hardy in zones 3 or 4 to 8. Their shape ranges from extremely narrow to tightly oval.

Pyramidal European Hornbeam
(Carpinus betula ‘Fastigiata’)

Carpinus betula ‘Fastigiata’. Photo:

With a rigorously upright and dense habit and attractive ribbed and toothed dark green leaves, this tree is widely used in Europe for tall hedges and windbreaks, but also grows fine on its own. It is marcescent, that is to say that after its leaves turn bright yellow in the fall, they don’t all fall off. Instead, many, now beige, hang on all winter, ensuring extra good density. They do fall off come spring as new leaves come in. For well-drained soils in sun or partial shade. Dimensions: 30 feet x 20 feet (10 m x 7 m). Hardiness zones: 5 to 8.

Upright English Oak
(Quercus robur ‘Fastigiata’)

Quercus robur ‘Fastigiata’. Photo:

Very popular, this oak has dark green leaves with rounded lobes and a very short petiole. As with the pyramidal European hornbeam, it is marcescent and its leaves turn brown in the fall, but don’t all fall off, ensuring some winter interest. For full sun in well-drained soil. It’s a very tall tree: 50–60 feet x 10–20 feet (15–18 m x 3–6 m). The cultivar ‘Skyrocket’ is even narrower. Zone 4 b to 8. 

There are several other pyramidal and columnar oaks. Ask about them at your favorite nursery.

Italian Cypress
(Cupressus sempervirens ‘Stricta’)

Cupressus sempervirens ‘Stricta’. Photo:

No, this is not a good choice for cold-climate gardens, but it is the “original” columnar tree, grown for over 2,000 years and, indeed, spread throughout the Mediterranean region by the ancient Romans. It’s the tall, narrow, upright conifer that you see everywhere in Tuscany and Provence and in cemeteries in mild climates the world over. Like most coniferous trees, it remains green all year long and is said to live up to 1000 years, although it remains very narrow, even at full maturity. That said, in home gardens it’s typically pruned occasionally to maintain an even narrower shape. There are also some extra narrow cultivars, like ‘Totem’. For full sun and well-drained soils. It’s a big one: 50–65 feet x 6 feet (15–20 m x 2 m)! Hardiness zones 7 to 10.

Weeping White Spruce
(Picea glauca ‘Pendula’)

Picea glauca ‘Pendula’. Photo:

Most weeping trees have a very wide habit, often broader than tall, but this tree is an exception to the rule. Its main stem is perfectly upright, but none of its secondary branches seem to have any tonicity, dripping down like a wet rag. So, although it grows taller and taller over time, it never becomes much wider. Its needles are numerous and dense, dark green with a whitish tinge. They keep their coloration all winter. Full sun in a moist, well-drained soil is ideal. Best adapted to cooler climates. 50–65 feet x 5–8 feet (16–20 m x 1.5-2.5 m). Hardiness zone: 2 to 6.

Tower Poplar
(Populus × canescens ‘Tower’)

Populus × canescens ‘Tower’. Photo:

Although the Lombardy poplar (Populus nigra ‘Italica’) is probably the most widely cultivated columnar tree in the world, is too prone to diseases for it to be a good choice as an urban tree. That’s where the Tower poplar steps in. It certainly looks like a Lombardy poplar, but is much less sensitive to fungi and bacteria. Since it’s a male plant, it won’t produce unsightly “white fluff” in the spring, a trait common on other poplars. Its habit is very narrow and it bears dark green leaves in the summer that turn bright yellow in the fall. For full sun and somewhat moist soil. 40 feet x 10 feet (12 m x 3 m). Hardiness zone: 2 to 6.

‘Prairie Sky’ poplar (P. × canadensis ‘Prairie Sky’) is similar, but with even better disease resistance. Its distribution is spotty, but it’s a great choice where it’s available.

Columnar Swedish Aspen
(Populus tremula ‘Erecta’)

Populus tremula ‘Erecta’. Photo:

An even narrower poplar than ‘Tower’, with green-white bark and leaves that shake in the slightest breeze. Certainly, the most attractive of the upright poplars. It’s said to be less likely so sucker than other poplars, but if you damage its roots, it will produce offsets by the dozens! It too is male plant, so will produce no fluff. Full sun, well-drained soil. 50–65 feet x 10–13 feet (15–20 m x 3–4 m). Zone 2b to 5.

Obviously, the columnar trees described above are just a glimpse of those on the market. Visit a nursery specializing in trees and you’ll discover many other narrowly upright trees; certainly one that will catch your eye!


Will Conifers Resprout From a Stump?


Question: I’ve noticed that many trees will sprout from the stump when you cut them down, but conifers never seem to do so. Are they all incapable of sprouting from the base?

A. Pospisil

Answer: You almost had me stumped with this question. I nearly replied yes, based on my experience: I’ve never seen a conifer resprout from a stump. But then I recalled hearing that, after Hiroshima, ginkgos (Ginkgo biloba) that had been nearly blasted out of existence did resprout. Now, officially ginkgos are not conifers, but they are gymnosperms, very close relatives. If ginkgos can resprout from the trunk, maybe some conifers can too.

It turns out that most conifers are indeed incapable of sprouting from the base: they have no dormant buds on the older parts of their trunk and certainly not at their base. This includes most conifers commonly grown in colder climates like mine: spruces, pines, firs and larches. However, there are some conifers that do bear dormant buds on old wood and some of these can resprout even if cut back to the ground.

Conifers That Can Resprout

A whole cluster of trees has sprouted from this very old stump of a coastal redwood (Sequoia sempervirens), including two already very tall trees. Photo:

Here is a partial list of conifers that are capable of resprouting from a stump:

Araucaria (Araucaria, some species)
Celery pine (Phyllocladus spp.)
Coast redwood (Sequoia sempervirens)
Japanese cedar (Cryptomeria japonica)
Juniper (Juniperus spp.)
Kauri (Agathis spp.)
Patagonian cypress (Fitroyza cupressoides)
Pine (Pinus, some species, mostly of subtropical origin)
Plum yew (Cephalotaxus spp.)
Podocarpus (Podocarpus, some species)
Yew (Taxus spp.)

Garden Myth: If You See Birds Eating Berries, They’re Edible


I can recall my father telling me this as a child. And just recently heard it again on a news report on TV, of all places, but it simply isn’t true. (Sorry, Dad!)

Birds can digest many berries that humans can’t safely eat, even poison ivy berries. Dogs and cats (especially the latter) are even more sensitive to chemical compounds found in berries than humans and the choice of berries they can safely eat is even more restricted. They can be poisoned by grapes, for example. 

Berries to Beware Of

Here are some examples of berries that are edible to birds, but poisonous to people and many pets:

Bittersweet nightshade (Solanum dulcamara) has attractive but poisonous berries. Photo:

Asparagus (Asparagus officinalis)
Baneberry (Actaea spp.)
Bittersweet (Celastrus spp.)
Bittersweet nightshade (Solanum dulcamara)
Boston ivy (Parthenocissus quinquefolia)
Buckthorn (Rhamnus spp.)
Chinaberry tree (Melia azedarach)
Clivia (Clivia spp.)
Common ivy (Hedera helix)
Cotoneaster (Cotoneaster spp.)
Cuckoo pint (Arum maculatum)

All parts of different daphnes, such as the February daphne (Daphne mezereum) seen here, are poisonous, including the berries. Photo: Wikimedia Commons

Daphne (Daphne spp.)
Deadly nightshade (Atropa belladonna)
Elderberry (Sambucus spp.)**
Euonymus (Euonymus spp.)
Garden huckleberry* (Solanum nigrum)
Golden dewdrop (Duranta erecta)
Herb-paris (Paris spp.)
Holly (Ilex spp.)

Not all honeysuckles have poisonous berries, but choosing safe ones is complicated, so it’s best to treat them all with suspicion. Photo: Ben,

Honeysuckle (Lonicera spp.)
Horsenettle (Solanum carolinense)
Jasmin (Jasminum spp.)
Jerusalem cherry (Solanum pseudocapsicum)
Lantana* (Lantana spp.)
Lily of the valley (Convallaria majus)
Manchineel (Hippomane mancinella)
Mayapple* (Podophyllum spp.)
Mistletoe (Viscum spp. and Phoradendron spp.)

Moonseed berries (Menispermum canadense) are sometimes mistaken for grapes… with fatal consequences. Photo:

Moonseed (Menispermum spp.)
Poison ivy (Toxicodendron spp.)
Pokeberry (Phytolacca spp.)
Potato (Solanum tuberosum)
Privet (Ligustrum spp.)
Virginia creeper (Parthenocissus quinquefolia)
Yew*** (Taxus spp.)

*Unripe berries only
**The berries of some species are edible after cooking.
***The berry itself is edible when ripe, but the seed is poisonous.

Here’s a good rule to follow: if you don’t know for sure a berry is edible, don’t eat it!

Father’s Day: Plant a Tree for Dad


Looking for an interesting gift for Dad on Father’s Day (the third Sunday in June)? Why not plant a tree in his honor?

You could take him to the plant nursery and help pick one out. Or surprise him with your choice of tree. A child without much of a budget could plant an inexpensive seedling.

Look for a long-lived species. Probably the longest lived is the ginkgo (Ginkgo biloba), which can easily live for 300 years, but there are dozens of others you could expect to live 80 years or more.

Make sure, too, the tree is adapted to local growing conditions: does it need sun or tolerate shade? Adapt to dry soils or moist ones, clay or sand, acid soils or alkaline ones, etc.? And consider hardiness too: it needs to be able to survive the winter in the region where you plant it. 

A garden center employee could help you make an appropriate choice.

You may be able to sponsor a tree in a public park. Photo:

You don’t have room for a tree? Why not contact a local public garden, arboretum or park and see if you can’t sponsor a tree in Dad’s name? That way it will be taken care of practically ad infinitum and even if you move, the tree will remain accessible.

Plant a tree for Dad, an enduring symbol of your love and respect.

Garden Myth: Eggshells Are a Good Source of Calcium for Garden Soils


You’re probably heard that eggshells are a good source of calcium and are an excellent addition to compost or even to add directly to the soil in your garden. In fact, eggshells are even recommended as a way of preventing blossom end rot in tomatoes*, a disease related to the unavailability of calcium in the soil. 

Now, this sounds very logical: eggshells are 95% calcium carbonate, after all. Doesn’t it stand to reason that they’d up the amount of calcium available to plants if you added them to compost or soil?

But that’s without considering the fact that eggshells don’t break down readily. In fact, archeologists regularly dig up middens (refuse mounds) hundreds of years old and the eggshells are still there, largely intact. As a result, very little calcium from eggshells is actually returned to the soil in any way useful to plants, at least during the lifetime of the gardener. 

Actually, if you’re an astute composter, you’ll already have noticed this: when your compost is “ready” for garden use and all the other ingredients have decomposed, you’ll still see abundant bits of undecomposed eggshell. 

Unusual Conditions Can Help Decomposition

Under special circumstances, eggshells will break down much faster.

Under very acid conditions (a pH of less than 4), for example, they will decompose quite readily, especially if reduced into powder, but you’ll find very few compost piles or garden soils in that range. (Actually, you wouldn’t want your garden soil to be that acidic: very few plants can tolerate extremely acid soils.)

If you do need calcium, you can dissolve ground eggshells in vinegar. Photo:

A rather extreme way of actually getting some value out of the calcium carbonate eggshells are made of is to “melt” them in acid! Pour plain kitchen vinegar, highly acid (a pH of about 3), over ground-up eggshells and let sit overnight (or longer, depending on the quantity and the size of the shell fragments). The acid will cause the shell bits to dissolve, releasing carbon dioxide and leaving calcium and water you could then add to your garden’s soil.

They will also decompose faster in hot compost; that is compost where the temperature rises to 40 to 60 °C (100 to 140 °C). Even then, they’ll need to be ground up very finely to decompose within a reasonable amount of time. And of course, most home compost bins, as well as garden soils, don’t get anywhere near that level of heat.

If there is a municipal compost program where you live, don’t hesitate to include eggshells. It is, in fact, probably the best way to recycle them. Ill.: &, montage

If your municipality has a compost pickup program, definitely make sure your eggshells go there. They’ll be doing hot composting and will make sure your eggshells are properly composted.

Much Ado About Nothing?

It’s important to realize that, in fact, most garden soils do not lack calcium, so you almost never need to add more. It’s one of the most common soil elements, abundant nearly everywhere. So all this concern about the calcium in eggshells is largely theoretical. Your garden will probably get along fine if you never add calcium, whether it be from eggshells or another source.

That said, you can still add eggshells to soil or compost. They’re harmless, after all, and it’s a good way of recycling them at home, especially if the alternative is sending them off to a municipal dump where they’ll just take up space.

Grind eggshells even more than this before you add them to the soil. Photo:

If you can, reduce eggshells to powder or at least to the smallest pieces possible. Try using a hammer, a pestle, a blender or, best of all, a coffee grinder. Small pieces will have the greatest chance of breaking down to something useful within your great-grandchildren’s lifetime. 

As to the common garden myth that eggshells can be used to control slugs, read more about that here.

Chicken Fodder

One truly useful thing you can do with eggshells is to feed them to chickens. They need a lot of calcium to produce eggs and their digestive system will break eggshells down. Yes, that does sound a bit cannibalistic, but chickens actively seek out anything containing calcium, even their own egg shells.

So, eggshells are not all that useful to the soil you garden in, but at least you can recycle them there and reduce your environmental footprint!

A Rubber Plant From a Leaf Cutting?


Question: I accidentally knocked a leaf off my rubber plant and have placed it in a glass of water. Will it root and produce a new rubber plant or am I simply wasting my time?


Réponse: Your rubber plant (Ficus elastica) leaf may well root, but it will never produce a new plant. 

Ficus leaves, especially those of large-leaved species—the fiddle-leaf fig, F. lyrata, for example—do have the capacity to produce roots from a leaf petiole if conditions are good. However, what they don’t have is the capacity to produce a new plant from a single leaf. There is no dormant bud on a ficus leaf that can eventually grow into a plant. You’ll get plenty of roots and the leaf may live on for months, even a few years (you’d have to pot it up into soil for that), but it will forever remain a single, lonely leaf.

Rooted leaves that never produce shoots are said to be “blind cuttings”. 

On the Internet, I often see thrilled indoor gardeners marveling over the leaf cuttings they took of a rubber plant: “Look,” they crow, “my leaf has roots!” They all look forward to the huge and beautiful rubber plant it will one day become, but they are going to be bitterly disappointed. 

A stem cutting from rubber plant, even one with only a single node, can root and produce a new shoot and, eventually, an entire new plant. Photo:

Now, if a piece of stem were included as part of the cutting, that would change everything. A stem cutting of such ficus plants, even only one with a single leaf, does have a dormant bud, found at the leaf base. So, if the stem roots, the bud will begin to grow and will soon produce a new plant.

But a leaf alone will be forever blind. 

There aren’t many plants that are capable of producing an entire new plant from a leaf cutting. African violets, streptocarpus, sansesverias, sedums, echeverias and (some) begonias are exceptions and will readily produce new plants from a healthy leaf. But none of ficus varieties will. 

Sorry to disappoint you!

Plant Tomatoes on Their Side


When you start your own tomato plants indoors, they tend to be a bit wimpy: tall and thin with few lower leaves. You may even feel ashamed about planting them in your vegetable garden lest your neighbors laugh at you!

Well, they won’t laugh if you apply the following trick:

Instead of planting scrawny tomato plants upright, dig a lengthwise hole and place them on their side, bending the top part upward so it remains exposed. Then just cover the bare stem with soil. The plant will instantly look perfectly sound … and roots will grow on the buried part, giving you an even more vigorous plant that you would have had it were it planted upright. So your scrawny homegrown tomato plant may well outdo the sturdy-looking but much more expensive store-bought one!

Warning: do not plant grafted tomatoes this way. Whether you buy them or grow your own, with these especially vigorous tomatoes, the graft union must always be above the ground. If you bury the graft point, the scion (top part) will take root and benefits of grafting (greater vigor, productivity and disease resistance) will be lost.

Adapted from an article originally published on June 3, 2015.