Category Archives: Garden Musings and Tips

Wintering Over Tender Perennial Roots

After a hard frost, unearthed Canna, Salvia, stored Dahlias

This article is appearing before most of us have had a killing frost, but take a moment to read this now so you’ll have an idea of what to do when the time comes. The processes described below are general and reliable instructions, but we’ve had luck simply wintering over dormant plants in the containers they were grown in, stored in cool, dark spaces which stay above 35F.

WAIT UNTIL AFTER there has been a killing frost, when the foliage has blackened and in some cases toppled over (you want to be sure active growth is halted). Then it is time to gently unearth the corms, tuberous roots and rhizomes of tender perennials such as Canna, Colocasia, Oxalis, Gladiolus, Dahlia, Salvia guaranitica, Mirabilis, Phygelius and others. Be careful, as cuts and breakage of fleshy tubers invite disease and decay. (If pieces of root become broken or cut, remove the affected divisions or treat with a garden fungicide to prevent fungal diseases from developing and spreading.) It is always a wise practice to sterilize shovels and forks after digging each clump, so as not to spread disease. Remember to write on a tag each variety of plant as they are dug, and attach. It is so easy to mix up root stocks, especially if you’re growing more than one selection of a certain plant.

The next thing you should do is clean and cure your roots. Wash off with a hose sprayer as much of the clinging soil as possible, which will rid you of possible pests and pathogens lingering in the soil. You may want to dip the clean roots in a fungicide solution at this point as a preventative action. (We may try the botanical all purpose Neem this year, which has fungicidal properties as well as insecticidal.) Lay the roots to cure or dry in a protected well ventilated area out of direct sunlight. This may take a few days or up to a week or two, depending on the plants, weather and temperature conditions.

In the meantime, locate some ventilated containers to store the roots, such as wooden crates or apple baskets. Plastic covered bins are easy to acquire, but be sure to puncture holes in the sides for ventilation. Be sure to include a label in each bin. First put down an insulating layer of clean wood shavings, almost dry peat moss, a well drained barky soil mix which is just a tad moist, or even sand, and lay down the roots, covering each layer with an inch of your medium, being careful to not to let the roots touch. Place the bins in a dark cool area that stays above freezing. A cool, slightly humid root cellar would be perfect, and if you live in an ancient house like we do, your cellar may be the perfect spot. Any basement, shed or garage that is dimly lit and cool will be fine, as long as it stays above freezing. You may want to check the bins occasionally to monitor if  mold is beginning to develop. If you do catch fungal problems, immediately discard the affected roots and remove what is left that look healthy. Treat the healthy roots with a fungicide, (acts as a preventative) and place in a clean bin with fresh shavings, soil mix or sand.

Wintering Tender Plants Indoors

Suddenly, one morning you wake up, and the chill in the air alerts you that autumn has unofficially arrived. Once the nighttime temperatures begin to dip into the 40’s, it’s time to start bringing plants indoors, beginning with those that are only hardy to the warmer zones 9, 10 and 11. (Think some Alpinia, Coleus, Cuphea, Acalypha, Alternanthera, Cyperus, Impatiens, etc.) If available space is a concern, be selective and choose the hardest to acquire specimens first. Do you have a warm space available that is well lit and humid enough for tropicals, such as a bathroom or laundry room? Remember that indoor heating systems create a warm but dry air environment. Plants that prefer more arid conditions, such as tender succulents, Pelargonium, and some Begonia easily adapt to the transition indoors.

Important! Here are two things you should do first. The days are getting shorter and there is less light available indoors. Plants will begin to respond to the change in temperature and light by dropping foliage, and in some cases flower production ceases. To counter the low light levels, we recommend trimming back large leafy plants so there is less growth for the plants to support. Also, inspect plants for insect activity and as well as burrowing snails, slugs and other hitchhikers. Spray with a botanical pest control, such as insecticidal soap or Neem. Spray again in 7-10 days to arrest any late hatching, and monitor in the weeks to come.

Plants that are hardy to zones 7 and 8 can handle cool winter temperatures in the 35-40 degree F. range, and will do well in a sunny attic, basement or garage. These plants include Abutilon, Phormium, Fuchsia, Phygelius, Hebe, Coprosma, Astelia, Centaurea, many Salvia and Pelargonium, to name a few. Remember that since their growth has slowed down due to lower light levels, stop fertilizing and water just enough to keep them from drying out, since  constantly wet soil contributes to root rot.

Next week’s article: Storing dormant roots.

Wintering Over I: Taking Cuttings

Saving Coleus Cuttings

You may have acquired a collection of stunning tender perennials that have added so much to your containers and gardens, but soon, frost will be imminent. Before you drag dozens (hundreds?) of pots indoors, first consider how much storage room your home/garage/cellar offers, (let’s assume you don’t have a greenhouse, but if you do, terrific!). Usually space is quite limited, and you’ll need to be ruthless in deciding what gets saved. Focus on the hard to find varieties. Next, decide what needs to be actively growing, and what can be stored as dormant roots (more on that in later blog postings). In general, plants that are the least cold tolerant (zones 9, 10 and 11), i.e. Coleus, need to be kept in an active state and need warm indoor temperatures.

We found that taking cuttings of easy to root plants like Coleus, Salvia and Cuphea is one way to limit the number of big bushy plants that will compete for light on your windowsill. Begin taking cuttings at the beginning of September and be sure to label each variety. Select non flowering tips with 2-3 nodes and remove the lower leaves. Dip the tips in a light rooting hormone and stick in a tray or pot of a light potting medium or sand. Place in a shady warm spot and water/mist several times a day for the next 2 weeks or so. A gentle tug will let you know when roots have taken hold. Once decent roots are set, gently unearth and transplant into small pots, or leave in the rooting pot itself. Go light on the fertilizing this fall and winter, since you do not want to encourage too much growth. In the spring, transplant into a richer soil mix. You can begin taking more cuttings as soon as vigorous fresh growth permits.

An Aster by Another Name

raydon

Symphyotrichum ‘Raydon’s Favorite’ with Dendranthema ‘Sheffield Apricot’

Are you confused? We were. Asters were one of the easy botanical names to remember, since the common name was exactly the same as the Latin name, until maybe a decade ago.  We started to notice that certain wholesale sources were listing many common fall aster species as Symphyotrichum (pronounced sim-fy-oh-TRY-kum). This brought up questions. Will this name take hold with the gardening public? Should we reclassify the plants we were calling Aster? And which asters were considered in the genus Symphyotrichum? Would our customers know to look under this new genus name when seeking the fall blooming asters?

Upon research we discovered that once botanists began comparing the DNA of Eurasian Asters with North American species, they found that the asters native to North America were more closely related to other native genera, especially Boltonia, Solidago and Erigeron. To be brief, the North American Asters included in the Symphyotrichum group are the species: cordifolius, dumosus, laevis, lateriflorum, novae-angliae, novi-belgii oblongifolius. Two New World Asters, divaricatus and macrophyllus are now considered to be Eurybia species.

Some of the Eurasian species have been reclassified into the genera Crinitaria, Galatella and Bellidiastrum, (few of which are commercially available here in the US) while others still remain in the genus Aster, including Aster amellus, ageratoides and tartaricus. The question remains as to what would be the correct nomenclature for Aster hybrids, such as the new selection Aster x ‘Blue Autumn’, recently introduced in the US by European breeders as a cultivar of Aster laevis, incorrectly we might add. We’ll keep you posted when we know for sure.

What’s Eating My Plants? I

Tobacco Hornworm

Don’t you just hate this? One day you have a perfectly healthy plant, and the next time you look, the leaves are riddled with holes, or completely gone! Just 2 days ago, I photographed a lovely stand of Nicotiana mutabilis (Flowering Tobacco). As I walked by this morning, I was stunned by totally denuded stalks. On closer inspection, there was a 4″ Tobacco Hornworm chomping away, leaving behind a trail of excrement. Not a pretty picture now.

The Tobacco Hornworm Manduca sexta is the caterpillar of a type of Sphinx Moth or Hawk Moth. It differs from the Tomato Hornworm by having a reddish instead of a black “horn”, and you can also tell the difference by its lateral markings. The Tobacco Hornworm has seven diagonal lines, while the Tomato Hornworm has eight v-shaped markings.

The adult female Sphinx Moth deposits her translucent green eggs on the undersides of leaves of plants in the Solanacea family, especially Nicotiana (Tobacco), and take 2-4 days to hatch. During their larval stage, these Hornworms feed on the foliage, flowers and fruit. They can ingest the toxin Nicotine without ill effects, and their voracious appetites allow them to strip even large plants overnight. Their green bodies camouflage well with the plants they feed on.

Control this pest by handpicking the caterpillars. If you have too large a crop for handpicking, you can use a product like Dipel (Bacillus thuringiensis) or Monterey Garden Spray (Spinosad) on the young larvae. Be on the lookout for hornworms with little white “pills” attached. These white attachments are the eggs of the parasitic Braconid Wasp, which feed on and weaken/kill the unsuspecting hornworm. This biological control is a good example of nature keeping everything in balance.

The Right Time to Plant Tender…

Here in the northeast, mid spring teases us with periods of warm sunny days, tempting us to go out and buy the colorful annuals and tropical perennials stocked in local greenhouses. We forget that we may well get several more chilly nights. Perhaps frost is unlikely, but the soil temperature is going to remain too cold for the heat lovers until nights stay above 55 degrees F. If you plant these warm weather gems too soon, you will most assuredly stunt their growth.

The old timers always said to wait until Memorial Day to plant tomatoes and annuals, and for good reason. Only last year, many of us experienced a cool wet June, and many a northern gardener lamented how poorly Coleus, Colocasia and Cannas performed.

Pruning Hydrangea

Hydrangea paniculata ‘Limelight’ blooms on new growth

Even seasoned gardeners seem to be confused as to when to prune Hydrangea.

Begin by identifying which Hydrangea species you are growing, to determine whether it will bloom on new growth or on old wood (last year’s stalks). The species arborescens, paniculata and some newer forms of macrophylla bloom on new wood. All the Hydrangea macrophylla (Mophead and Lacecap types) and quercifolia (Oakleaf)  bloom on old wood, as long as there isn’t winter damage. Next year?s blossoms are set on the upper portion of the woody stalks in late summer and fall. H. macrophylla selections should not be pruned until after the plants have leafed out. In late spring, prune out or tip back any dead wood for a clean appearance.

The hardiest and most foolproof of all the Hydrangea are the paniculata group (Pee Gee types) and the arborescens group (Smooth Hydrangea). Both of these species can be cut within inches of the ground each spring if you want to control the size of your plants.  They stalks can always be thinned to improve plant shape, and there is no harm to next year’s display if you want to cut long stemmed bouquets in summer and fall.

There are a lot of new Hydrangea macrophylla selections on the market, including ‘Double Expressions’, ‘Red Sensation’, ‘Let’s Dance Starlight’, and ‘Endless Summer’ that bloom on old and new wood. The blossoms appearing on old growth will display in early summer, while the flowers that form on new growth will appear later in August and September, for a long continuous display. If you live in the colder parts of zone 6 or zone 5, you may get too much winterkill for blossoms on the old growth, but you will still be able to enjoy a late summer through fall display.

Making Your Bed for Spring III

Should you lime your garden?

Here in the northeast, we seldom consider the effects of acid rain anymore.  Since most public water departments deliver water with a neutral ph, the effects of acid rain have been largely neutralized in landscapes that use public water.  Still, we cant be certain of the soil pH unless we periodically test it. it is a good idea to purchase soil pH testers, either online or at a local garden centers.

Making Your Bed For Spring II

Be on the lookout…there may be treasure in your garden.

During your spring cleanup, you will no doubt uncover all kinds of delightful signs of life: the healthy shoots of perennials, dozens of tiny seedlings or wiggly earthworms under fallen leaves. One treasure you should be on the lookout for, and not mistake as something bad is the over wintering egg case of Praying Mantes (or Mantids). These pale tan Styrofoam looking sacs are attached in the crotches and on the undersides of bare branches. In late spring they will begin to split, upon which a hundred or more tiny translucent Praying Mantes will unfurl and march away to devour a wide variety of your most irritating garden pests. We were absolutely delighted to learn that they voraciously eat grasshoppers, which are a nuisance we’ve had difficulty with in the past.

The Praying Mantis is a most fascinating insect to observe in the garden. They sit motionless in the garden waiting for their prey to pass by. And yes, it is true that the females practice sexual cannibalism, (but not always, we’re told). Often the male is just not thinking straight when he has copulation on his mind and surprises the female as she sits motionless. Her first reaction is to grab hold and bite off his head (she needs the extra protein for pregnancy!). The male is able to fulfill his mission nonetheless and we hear he dies happily ever after.

Making Your Bed For Spring I

Tending to Hellebores in March

One of the first things we tackle in the garden is raking up windblown leaves that have accumulated around the crowns of the early blooming Lenten Roses (Helleborus orientalis hybrids) and removing last year’s tarnished foliage, which may harbor pesky Botrytis spores.

As you cleanup the decaying growth, you may be fortunate to discover dozens of tiny seedlings at the plant’s base (of course that’s if the Hellebore bloomed well for you last year).  These seedlings may be variable in color, especially if you’re growing a hybrid selection or more than one variety. You can always leave them undisturbed, and a few will eventually establish in situ or you can very gently lift the delicate seedlings and transplant them into small pots using a well drained potting soil. After a few months they will have put on enough growth for transplanting to other spots in your garden.