Keeping Potted Strawberries Alive Over the Winter

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Ill.: http://www.kissclipart.com & http://www.greenplumbingnj.com, montage: laidbackgardener.blog

Question: At the beginning of the season, I bought a hanging strawberry plant and, surprisingly, it really produced lots of strawberries. I’m very pleased with the results! However, with autumn coming on, I’ve begun wondering how to keep it for next year. What do you recommend?

J. Arcand

Answer: Strawberries (Fragaria × ananassa) are actually very hardy, much hardier than they are usually given credit for being. Most will grow perfectly well in hardiness zone 3, even 2, depending on the cultivar, and that’s cold! 

However, that applies to strawberry plants growing in the ground, with their roots surrounded by a large mass of soil, because soil is actually a good insulator. 

The situation is very different for strawberries grown in pots, at least where winters are very cold (zone 7 and below). Container-grown strawberries are exposed to cold from all sides, even from underneath, and may well freeze solid during a cold winter, a situation that could end the life of even the toughest strawberry. So, some protection will be required.

Indoors

The easiest solution is probably to place the plant in a slightly heated garage, a root cellar or any other cold but frost-free spot. You don’t even have to be in rush to do this. Just leave your hanging basket outdoors through most of fall, allowing it to undergo a touch or two of frost first, as that will help push the plant into full dormancy. Carry it in to your “shelter” only when serious cold threatens. 

During the winter, even though your plant will be dormant, do water it lightly from time to time, just enough to prevent it from drying out completely. And since it’s dormant, no light will be needed. 

Outdoors

Put those fall leaves to good use as a mulch for your strawberry basket. Photo: homconte.com

If you don’t have a cold but frost-free spot where you can shelter your hanging strawberry indoors, try placing the pot on the ground outside, if possible against a wall of the house that will cut off part of the wind and give off some heat. Now, cover it with a thick mound of fall leaves, straw or some other insulating mulch. You can use a net or old cloth to hold the mulch in place. That will insulate it against the worst cold.

You could also “plant the pot” in the garden for the winter. Dig a hole, drop the pot in and fill in all around with soil. Finally, cover pot and plant with a good mulch for additional protection. Come spring, dig up the pot, wipe it off and hang the container up again.

Finally, you can also take the plant out of its pot and plant it in the ground for the winter, still covering it with mulch. In this case, you’ll have to repot it next spring.


There you go: four easy solutions for overwintering container-grown strawberries!

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Confessions of a Pot Hoarder

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Behind this outer wall of partly cleaned pots are shelves 2-feet wide jammed full of pots of all sizes. Photo: laidbackgardener.blog

Yes, I’m a pot hoarder. I have thousands of pots stored in my basement, more than I could ever possibly expect to use, yet I continue to collect more. 

Like many hoarders, I didn’t realize I had a hoarding habit. I was just putting pots aside for future use, after all. Then one day I was showing a plant friend my potting bench and work area and she pointedly remarked, “You do know that you can take used pots to the garden center and they’ll reuse or recycle them, don’t you?” I immediately made excuses for why I really did need all of those pots for future plantings and she just sighed. Caught out! 

I do give pots away … sometimes. OK, rarely. Only to deserving plant people. Or to my kids to encourage them to become deserving plant people. Mostly, though, they just build up and up. 

Of course, I don’t just accumulate. When I’m potting plants up, I do use my recycled pots … but in spite of the huge numbers, I always seem to have a hard time finding exactly the size I want. With thousands of pots stored away, how is that even possible? Yet it happens. 

It’s the larger ones that run out. Like any gardener, I keep potting smaller plants into larger ones as they grow. Eventually I reach the point where they’re all taken, so I buy more. I never buy small pots or even medium pots: I have plenty of those!

Pots come in such a mix of sizes and shapes that stacking them becomes an art in itself. Photo: http://www.telegraph.co.uk

I classify pots according to size, inserting one into the other to save space (for more pots to come, obviously). That’s when you realize there is an extraordinary number of pots shapes and sizes on the market. And that makes storing them a nightmare. Some pots are a bit taller, a bit wider at the base, a bit narrower than others, so stacking them logically is quite a hassle. Couldn’t pot manufacturers just choose a limited range of standard pot sizes and stick to those? But obviously, they don’t even speak to each other, as the range of pot sizes just keeps on growing. And I keep desperately trying to put them into some sort of reasonable order.

A Magazine Hoarder

Just part of my magazine collection. Photo: laidbackgardener.blog

My hoarding habits extend to gardening magazines too. I have 45 years-worth of them! For some, I have the whole series, from the first publication to the last. (Yes, sadly, so many plant magazines are no more!) I almost never consult them, although that’s the reason I give myself to explain why I keep them. 

Most are magazines I subscribe to or used to subscribe to. Others are gifts from plant friends who had no room for theirs. I doubt if I’ve ever opened one of those, yet I hang onto them, too.  

Although I now realize I’m hoarding, I still can’t imagine actually getting rid of my excesses. Nope, I figure I’ll just hang onto them, as I still do have room for more. Honestly, I really do! 

When I die, though, someone is going to need to organize a major pot and plant magazine give away!

Discoveries From the GardenComm Conference

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Photo: Janet Carson, http://www.arkansasonline.com

Every year for over 30 years, I’ve been attending the annual GardenComm* show and conference, held in 2019 in Salt Lake City, Utah. And every year, I come away with some great new plant and product ideas for my own use and to share with my readers. These are all either already on the market or scheduled for launching in the coming year.

*Garden Communicators International, formerly the Garden Writers Association.

Here are some of my discoveries for 2020:

Iceberg Alley™ Sageleaf Willow
(Salix candida ‘Jefberg’)

Iceberg Alley™ Sageleaf Willow. Photo: http://www.baileynurseries.com

This low-growing, rounded, silver-leaved shrub is unique, not the least of its attributes being its extreme hardiness (USDA zone 2). It will slowly reach from 3–4 feet (90–120 cm) in height and diameter (it will be at its tallest in milder climates). A male plant, it also bears attractive silvery catkins with colorful stamens in early spring. 

The silvery catkins pick up further color as the stamens appear. Photo: http://www.baileynurseries.com

It’s extremely well adapted to harsh conditions and does best full sun or, at least, no more than very light shade. It naturally grows in somewhat moist soil, but adapts well to dry conditions once established. It comes from limestone areas of northern Newfoundland, so it’s well adapted to alkaline soils (Prairie gardeners will love it!), but also seems perfectly happy in more acid ones as well. It does like a cold winter and won’t be happy in a hot climate. It’s southern limit appears to be about zone 6.

The shrub was discovered in Newfoundland by Todd Boland of Memorial University of Newfoundland and Labrador.

‘Redarling’ Brussels Sprouts 
(Brassica oleracea gemmifera ‘Redarling’)

‘Redarling’ Brussels Sprouts. Photo: http://www.syngenta.com

Here’s a brilliant red-purple hybrid Brussels sprouts with a slightly sweeter flavor than most green varieties. The plump, jewel-like 1½ inch (3.8 cm) buttons mix the typical Brussels sprouts bite with mild sweetness. Color-fast buttons are scrumptious steamed, broiled, or roasted—and excel as conversation-starting canapes. Easy-growing, prolific plants. And maybe its attractive color might make it more acceptable to young children!

Dimensions: 30–40 inches (75–100 cm) x 20–30 inches (50–75 cm). Maturity: 140 days.

Poprocks™ Petite Japanese Spirea
(Spiraea japonica ‘Odessa’)

Poprocks™ Petite Japanese Spirea. Photo: bloomineasyplants.com

This is probably the most compact and dense Japanese spirea ever introduced. Reaching only 3 feet (90 cm) tall and wide, it features a tidy, compact mature form and eye-catching candy-pink button flowers that pop against rich green foliage. And it blooms non-stop right through the summer: no deadheading required. It will need full sun and average garden soil and is hardy from zones 3 to 8. Use it as a border plant or low hedge.

Wild Valley Farms Wool Pellets

Wild Valley Farms Wool Pellets. Photo: http://www.wildvalleyfarms.com

Certainly, the most original fertilizer product I’ve seen in years, these wool pellets are made from waste wool, fleece from the underbelly and tags that can’t be utilized to make clothes and is usually thrown away. Used in the garden, though, the pellets provide a 9-0-2 fertilizer to your plants that lasts all summer (in fact, more than six months), but that’s not all. They also increase the porosity and water holding ability of the soil. In fact, they can reduce watering needs by up to 25%! And here’s a secret: they tend to repulse slugs and snails!

Wool pellets can be used in the garden and indoors as well (use them to replace perlite when you prepare your potting mix). If you can’t find them in local stores, contact the supplier directly: www.wildvalleyfarms.com.

Beacon™ Impatiens 
(Impatiens walleriana Beacon series)

Beacon™ Orange garden impatiens. Photo: http://www.panamseed.com

Yes, the garden impatiens is definitely back. After 2019’s Imara™ XDR series impatiens by Sygenta, PanAmerican Seeds offers its new line of mildew-resistant impatiens, Beacon™, for 2020. 

These plants are pure Impatiens walleriana, with all its shade resistance, but will not die from impatiens downy mildew (Plasmopara obducens), the devastating disease that practically wiped the garden impatiens off the market in 2013. The new series comes in 6 colors and 2 mixes, so you can once again fill baskets, window boxes, and shade landscapes with confidence.

Try these new mounding impatiens (10–12 inches/25–30 cm x 12–14 inches/30–36 cm) everywhere you used to grow garden impatiens, that is from sun to deep shade. You can grow your own by seed or buy young plants in the spring. 

Garden impatiens adapt to most soils, but do keep them watered. Although these impatiens are usually treated as annuals, you can bring cuttings indoors for the winter if you want.

Everleaf Emerald Towers Basil
(Ocimum basilicum ‘Everleaf Emerald Towers’)

Everleaf Emerald Towers Basil. Photo: http://www.panamseed.com

Certainly not Grandma’s basil!

First of all, its upright growth habit with multiple short branches and short internodes make a nearly columnar plant (24–36″/60–90 cm x 8–12″/20–30 cm), ideal for small spaces. And also makes it highly ornamental. Even so, it has that traditional Genovese flavor, perfect for eating fresh in caprese salads or chopped fresh in recipes.

Better yet, Everleaf Emerald Towers basil rarely flowers! Experienced gardeners know that basil goes into decline when it blooms and pinch off flower buds as they see them, but you won’t need to do so with Everleaf Emerald Towers Basil! This is the first basil bred for season-long performance, flowering 10 to 12 weeks later than standard varieties (i.e. not at all in short-season climates like mine), so no flowers to remove. 

In my opinion, though, its best attribute is its excellent disease resistance.

For years, nurseries have been playing the ostrich about the ravages of two diseases of the basil they sell, downy mildew and fusarium, as if they think their customers won’t notice. But we did (how can you miss plants that die only weeks after you purchase them?) Well, with this new disease-resistant basil, you won’t need to worry about losing your plants in mid-season! 

Everleaf Emerald Towers basil is already offered in seed catalogs everywhere for the 2020 season. Check and you’ll see!

Peppy Le Pom Dwarf Pomegranate
(Punica granatum ‘SMNPGMF’)

Peppy Le Pom Dwarf Pomegranate. Photo: http://www.provenwinners.com

OK, so don’t expect to be eating the tiny, seedy, rather sour pomegranates this dwarf variety produces, but it is a step above the old ornamental “dwarf pomegranate” (Punica granatum ‘Nana’) that many of us have been growing over the years (mea culpa!). It has smaller, greener, denser leaves than the old-fashioned dwarf pomegranate, but the same bright orange dangling flowers appearing from through summer and into early fall, making it a most attractive plant. Plus, its habit is much denser and you can prune it to shape, even turn it into topiary (at least, if you’re more into pruning than I am). 

With a hardiness range of zones 7 to 10, this will only be a permanent outdoor shrub in milder climates. Elsewhere, bring it back indoors in early fall and enjoy it as a houseplant over the winter. 

Some of the flowers will produce small fruits. Photo: http://www.logees.com

Best in full sun. You can keep a bit on the dry side, but never let the rootball dry out completely. Eventual dimensions: 36–48 inches (90–120 cm) x 36 inches (90 cm).

You can learn more about growing dwarf pomegranates in the article Dwarf Pomegranate: Beauty Indoors and Out.


Of course, I saw much more than that at the GardenComm show: maybe I’ll show you more plants and products in the months to come!

Perennials Tulips Do Exist

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Darwin hybrid tulips are the best known perennial tulips. Photo: http://www.whiteflowerfarm.com

Tulips have the reputation of not being very long-lasting. With most, their bloom decreases from year to year. The first year they flower perfectly, the second, more modestly, with smaller flowers, and the third, even less abundantly with even smaller flowers. Usually, after 4 years, all that comes up are leaves! Fortunately, there is a solution to this problem … but first, an explanation:

Why Are Many Tulips Short-Lived?

In nature, all tulips are perennials. They come back year after year, dividing at their base over time to form clumps like any other perennial. But cultivated tulips were not developed with repeat bloom in mind. Instead, they were created to produce one single but very spectacular flower.

The modern tulip was developed as a cut flower, not a garden plant. Benchmark Boquets, http://www.amazon.com

It is important to understand that the majority of tulip bulbs produced in the world are used in the cut flower industry, and this has been the case for over 200 years. All that cut flower growers ask for in a tulip is one single perfect flower on a solid stem. That’s because, after they harvest the flower, they dig out the bulb and compost it, long before it has had time to mature. Then they plant a fresh bulb in its place. That the plant has no staying power is of no concern to them.

So, for generations, tulip breeders have been working on developing tulips that meet the needs of cut flower growers, producing a single but spectacular bloom. The result is that many modern tulips are little more than biennials. This particularly true of Triumph tulips, which are by far the most widely sold tulip bulbs.

Choosing the Right Bulb

But you can grow long-lasting tulips, bulbs that will bloom every year, each time as beautifully as the first, for 5, 10, 15, even 20 years. But to do so, you first need to know how to choose the right bulb.

That’s because some tulips are longer lasting than others. In fact, bulbs in three categories are much more persistent than the others.

1. Botanical Tulips

Tulipa praestans ‘Fusilier’ is a popular botanical tulip. Photo: http://www.jparkers.co.uk

These are wild tulips or hybrid tulips closely allied with wild tulips. There are about 75 wild species of tulips and all are true perennials, so it makes sense that botanical tulips would prove to be perennials when they are grown in our gardens.

Of course, the “botanical tulips” we buy are not exactly wild. Most have been in culture for centuries and many so-called botanicals are hybrids and selections, not the wild species itself. (If so, they generally bear cultivar names, such as Tulipa praestans ‘Fusilier’ or T. greigii ‘Toronto’.) Still, they are still very close to the original wild species and are just as perennial.

Tulipa tarda: a beautiful botanical tulip that doesn’t fit our image of a typical tulip. Photo: http://www.farmergracy.co.uk

Of course, not all botanical tulips correspond to our image of a tulip. The majority are small plants, many with short flower stalks (unlike the tall ones of hybrid tulips) and small flowers. In addition, many produce multiple flowers per bulb rather than a single flower. And their leaves can be narrow or wavy-edged unlike the broad leaves of hybrid types. Still, they are true tulips and are very perennial.

Tulipa greigii ‘Cape Cod’. Photo: http://www.gardenersdream.co.uk

Among the botanical tulips that are easy to grow in home gardens are Tulipa kaufmanniana and its hybrids (‘Ancilla’, ‘Concerto’, ‘Johann Strauss’ and many others), T. greigii and it hybrids (‘Cape Cod’,’ Pinnochio’, ‘Toronto’ and many others), T. fosteriana and its hybrids (the ‘Emperor’ series is the most widely grown), T. tarda (sometimes considered a subspecies of T. urumiensis), T. turkestanica and T. praestans. Note that most botanical tulips do not need deep planting to perennialize well: the standard recommendation of 6 inches (15 cm) is generally quite acceptable.

Tulipa bakeri: quite appropriately, this botanical needs to be nearly “baked” in order to rebloom well. It will grow best in arid climates where irrigation is not used. Photo: wildgingerfarm.com

But beware, not all botanical tulips persist well in gardens, at least, not in areas with summer rainfall. Some come from hot climates with dry summers, where no drop of water falls for months and months. These varieties are poor choice as perennial tulips in any climate where rain is likely to occur in summer or in gardens where irrigation is used. I suggest considering these tulips, which includes T. bakeriT. humilis, and their hybrids, such as T. ‘Lilac Wonder’ and T. ‘Eastern Star’, as annuals.

2. Viridiflora Tulips

Tulipa viridiflora ‘Greenland’. Photo: http://www.dejager.co.uk

These are tulips have chlorophyll not only in their leaves like any other tulip, but also in their flower. Thus, the flower is partially green. This somewhat surprising pigmentation gives them an advantage when it comes to storing energy. Since the flower also carries out photosynthesis, like a leaf, the bulb picks up extra reserves and thus tends to bloom again very well … provided you plant it deeply (more on that later).

Some examples of viridiflora tulips are ‘Spring Green’, ‘Greenland’ and ‘Artist’, but there are dozens more.

3. Darwin Hybrid Tulips

Tulipa Darwin hybrid ‘World’s Favourite’. Photo: http://www.lubera.com

These tulips are the result of a cross between T. fosteriana and more conventional hybrid tulips. This results in a huge tulip with a large flower and a bulb nearly twice as big as those of other hybrid tulips. Also, Darwin Hybrids inherit the perennial nature of their botanical relative, T. fosteriana. Several bulb catalogs even offer them as “perennial tulips”.

There are dozens of varieties of hybrid Darwin tulips, especially in shades of red, orange, yellow and pink. Examples include: ‘Big Chief’, ‘Red Impression’ and ‘World’s Favourite’. These are the mostly widely available perennial tulips in garden centers. If you see tulips being sold in open boxes with their extra-large bulbs on display for all to see, they’ll almost certainly be Darwin hybrid tulips.

Extra-deep Planting

Extra-deep planting will help tulips live for an extra-long time. Photo: fierceblooms.com

To make viridiflora and Darwin hybrid tulips truly perennial, you also have to plant them deeper than usual: 1 foot (30 cm) deep rather than 6 inches (15 cm), the depth usually recommended. Why? That’s because tulips produce bulbils (small bulbs) at the base of the mother bulb. Producing bulbils tends to undermine mother bulb’s health and energy and, worse yet, the resulting plants crowd the mother bulb. When a bulb is planted extra deep, however, the bulbils are smothered: their burgeoning leaves can’t reach the surface and they die sight unseen, without disturbing the performance of the mother bulb. That allows it to bloom again and again, sometimes for decades.

Also, extra deep planting puts the bulbs out of reach of squirrels: they never dig that deeply into the ground.

Good Basic Care for Perennial Tulips 

Of courses, for tulips to be able to bloom over and over for many years, you have to give them the right conditions. For example, they need full sun or nearly full sun and also rich, well-drained soil. Clay soils are poor choices for perennial tulips: at a depth of 1 foot (30 cm), they are often left sitting in water all winter and that is a recipe for disaster. If your soil is heavy clay, you’ll find your tulips will perennialize best in raised beds.

Also, perennial bulbs are heavy feeders. Fertilize them at planting time with bulb fertilizer and apply mycorrhizae to the soil for better root growth. And apply fertilizer or compost in the spring just as they stop blooming.

In the Northern Hemisphere, you can plant your perennial tulip bulbs anytime between early September and late November.

Long live your perennial tulips!

Article originally published on septembre 24, 2015. 

Strange “Flowers” on a Rosebush

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These fuzzy red growths are not flowers, but galls. Photo: Peter O’Connor, http://www.flickr.com

Question: We have been growing a wild rose for ten years now, but this is the first time we’ve seen these wonderful flowers form. I say “form,” since strangely, they seem to grow as much on the leaves as on the rose’s branches. They look like pompoms or balls of fur. They were green at first, but have now turned beautiful shades of yellow, gold, pink and red. Is it possible that they are a parasite of some sort?

Simon Lanctot

Answer: Yes, they are indeed parasites and they’re not flowers, but rose galls, usually called mossy rose galls, rose bedeguars or Robin’s pincushions. Bedeguar traces back to Persian and means “brought by the wind,” although they’re actually “brought” by insects, while “Robin” is the name of a forest sprite. 

They’re caused by a small black wasp known as the mossy rose gall wasp (Diplolepis rosae). The adult is rarely seen, but it pierces a stem or leaf vein with its ovipositor and lays up to 60 eggs inside. This causes the formation of a gall of variable size (the more larvae there are inside, the larger it becomes) covered with a mass of sticky filaments, giving it its typical mossy appearance. The gall is green at first, but becomes various colors as fall sets in.

The larvae feed on tissus inside the gall. Photo: Frank Vincentz, Wikimedia Commons

The larvae feed on tissues inside the gall. If you cut one in half, you will see that it contains holes that the larvae have dug as they fed. The larvae are even edible and considered a delicacy in some countries!

Certain wild roses such as Rosa arvensisR. caninaR. rubiginosa, R. dumalis and R. glauca (R. rubrifolia) are more prone to mossy rose galls than cultivated roses.

A Fascinating Life Cycle

Female mossy rose gall wasp. She’s tiny and rarely noticed. Photo: Thiotrix, Wikimedia Commons

The life cycle of the insect begins with eggs being laid in May. The larvae grow all summer, passing through five instars, and form overwintering nymphs in late fall. In the spring, after a short pupation, a new generation of wasps emerges from the gall. They are almost all females, as this insect usually reproduces by parthenogenesis (without needing fecundation from a male). Then the cycle starts all over again.

But that’s the simple version. In fact, the larvae are often parasitized by other wasps and these are sometimes parasitized by yet other wasps. This is called hyperparasitism. Thus, there is often more than one species of larva inside the gall.

Mossy rose galls are most often found on somewhat stressed roses, for example those growing in very dry soil or very humid ones and also on heavily pruned plants.

Rose leaf with galls. Pretty, isn’t it? Photo: easywildflowers.wordpress.com

The gall itself is essentially harmless and its presence does not seem to weaken the plant in any way, even when it bears many galls. Purists will tell you to remove the galls you find on your roses so that the gall population doesn’t increase next year, but since you find them attractive, I suggest you just leave them. After all, what’s the harm in allowing Mother Nature to continue doing her job?


The mossy rose gall: it’s less a pest than a fascinating lesson about the complexity of nature!

Bulbs and Mulch: A Great Combo!

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Bulbs (here, hyacinths) easily push up through mulch. Photo: nittygrittydirtman.com

Question: I want to plant many bulbs in my flower bed this fall. It’s covered with mulch and I’m afraid the mulch will prevent the bulbs from growing. Can you plant bulbs in a mulched bed without them being smothered? If so, how do you do it?

Maude

Answer: Mulch and bulbs actually go very well together. 

Bulbs push their way right up through mulch. Ill.: http://www.mulchwholesalers.com, concretegarden.ca & http://www.turpinlandscapedesign.com, montage: laidbackgardener.com

Imagine: bulbs are planted fairly deep in the soil, yet their leaves easily manage to pierce the soil, often dense and heavy. Do you think a mulch, usually light and fairly fluffy, would stop such determined plants? Bulbs will easily grow through 4 inches (10 cm) or even more of mulch as if it weren’t there. 

Bulbs do this in the wild too, pushing their way up into the light, first through the soil, then the plant litter that covers the ground.

Perennials do just the same thing, by the way. They die to the ground in winter, then push their way up through any mulch present in the spring. 

So, proceed as follows:

Temporarily move the mulch from the spots where you want to plant bulbs. Plant them at the recommended depth (about three times the height of the bulb), add a little mycorrhizal inoculant, cover them with soil, replace the mulch, and water well. It couldn’t be simpler!

A Reminder

The purpose of a mulch is not to smother established weeds: they too will pass right through the mulch. What the mulch does is to prevent the germination of weed seeds. (And will also prevent bulbs and perennials from self-sowing, by the way.) That’s why you always have to thoroughly weed a flower bed before applying mulch: if any perennial weeds remain in the soil, they’ll just grow right up through the mulch. 

So think of it this way: mulch is not a weed smotherer, it’s an anti-germinator. And it won’t harm your bulbs!