March can be such a finicky month! Several years ago there was a long warm spell, only to be followed by two nights with extremely cold temperatures which killed many plants, including many Hydrangeas, to the ground! Some years we see snow storm after snow storm, while some years it is merely rain. Keep referring to notes or your diary from last year as to when you sowed seed and performed other chores as you need not reinvent the wheel. Also, keep making notes for this year so that you can see if any of the changes you made yielded better results!
Things to do:
- Remove excess leaves and or winter evergreen boughs from early sprouting perennials and bulbs.
- Finish, or perhaps start cutting back ornamental grasses and perennials. Remove the foliage of acaulescent Hellebores (Hellebores that produce flowers from the crown, not the tips of last year’s stems), such as Helleborus x hybridus cultivars or Helleborus atrorubens pictured at right. Try to tend to this as early as possible in the month so the declining foliage does not distract from the flower display or flower buds are accidentally removed.
- Cut and remove shrub or small tree stems that may have been broken during winter storms.
- March is time to finish pruning! Finish removing up to 1/3 of the older stems of Lilacs, Kerria, Forsythia, Slender Deutzia, Weigela and other multi-stemmed flowering shrubs. For Hydrangeas macrophylla, remove a few of the oldest stems, while Hydrangea arborescens cut to near the ground. Hydrangea paniculata cut back more aggressively if they have a more open panicle such as ‘Fire and Ice’ (pictured at right)
or just receive a light pruning if the flowers are dense with sterile florets. Purple and Golden Smoke Bush should be cut back to 6-12” to provide optimum foliage color, although such treatment will sacrifice summer blooms. Red or Golden Stemmed Dogwoods and Willows should be cut back to 6” or less every 2-3 years to encourage new shoots to develop, which will sport the best red or gold stem color. Have had great success with cutting red stemmed willows (Salix alba ‘Britzensis’) back annually. Vitex (Chaste Tree) can be cut back hard (to 12”) or moderately (3’), depending upon how tall you wish the plant to grow in your Garden – obviously, the less you cut it back, the taller the plant will grow this season. - Prune Butterfly Bushes back to 12-18” in height, and Russian Sage, Lavender, and Caryopteris back to approximately 6” in height. Do not prune Rosemary plants in spring, but rather wait until summer to shape and/or harvest stems.
- Prune 2-6’ long stems of Forsythia and Pussy Willow to bring inside for forcing. Salix ‘Mount Aso’ is an attractive pink flowered form of Pussy Willow, bred for the cut flower industry (pictured at left).
- Prune shrub roses back by about ½. For hybrid Tea Roses, cut plants back by ½, making certain that you cut to an outside facing bud (those small red dots, typically subtended by a leaf scar are leaf buds).
- Thatch lawns and overseed bare or thin areas. It is best to thatch the lawn when it is dry, allowing at least several days to pass after a rain before attempting to thatch.
- If Crabgrass was an issue in 2020, apply pre-emergent on lawns for Crabgrass control before Forsythia shows any flower color.
- Take soil samples from turf and vegetable garden areas to determine pH and soil fertility requirements. They should be submitted via a mailer that is available at the local extension office. Try not to walk on soil if it is wet or saturated, since it will compact, reducing the air spaces and destroing the soil structure.
- Edge bedlines and lightly remulch bed areas. If the beds were mulched last year, only 1-2” of new mulch should be needed unless there was significant erosion or the mulch was removed with the autumn leaves! Remember, shredded leaves make a great mulch!
- Seed out peas and radishes at the end of the month. The old rule of thumb was to sow the seed on St. Patrick’s Day, which may be too early and cold in northern NJ, unless you have very sandy and well-drained soils.
- Start Broccoli seeds indoors in early March, tomato seeds from mid-March on and eggplant, peppers and parsley towards the end of March.
- Remove your Canna, Colocasia and Alocasia tubers from their winter storage boxes, pot them up in an adequately sized container, and place in a sunny window. They will sprout best if bottom heat is provided. Water sufficiently to keep the soil moist but not wet until you start to see signs of life.
- Bring Brugmansia and Edible Figs out of the dark basement, start to water regularly and place in a warm sunny window.
- Any Plumaria (common name of Frangipani) that was stored in the basement should also be potted up and brought into an area with bright light.
- If you have a straggly Coleus plant (reclassified as Plectranthus scutellarioides a few years back and now once again Coleus scutellarioides!), you may wish to take cuttings and start new, stronger plants to move outdoors for summer display.
- Succulents that have been kept indoors should be repotted in spring if they have roots wrapping around the root ball when removed from the container. Or, if the roots have literally lifted the plant and the soil up to the lip of the pot and all the water runs over the rim when watered. Shake off some of the previous soil, prune off any decaying roots and repot in a container that is 2”+/- larger in diameter. Use a well-drained potting media, since succulents resent most soils.
- Groom your succulents as well, removing any brown and desiccated foliage. If the plant has become too leggy, as often happens after several months of low intensity light, you can cut off the upper portion of the plant that has foliage, let the wound callus over by laying it on a table for 3-5 days and then stick the rosette back into a container with well-drained soil. The stem will typically regenerate new roots and a new plant!
- Remove any tired or half-brown foliage from your houseplants and provide a 2-4 month granular feed or a ½ dilute liquid feed every month through September starting in March. As the day lengths get longer, the plants will start to grow and the extra feed will be appreciated.
- Many succulents can also be propagated by simply laying a leaf on top of the soil or even on a bench top (Echeveria leaves are pictured at right). A new plantlet and roots will typically appear at the base of the leaf within several weeks!
Bruce Crawford
Program Leader in Home and Public Horticulture (NJAES)
The most common species planted in Gardens, and very deservedly so I might add, is Galanthus nivalis. This species is also the type species for the genus, against which all species are evaluated and compared. This species was also named by Linnaeus in 1753, with the species epithet coming from the Latin meaning ‘of the snow’ or ‘snow-covered’. Typical to the genus, each bulb produces two linear leaves that ultimately grow to 6-8” long. The flower scape emerges from in-between the leaves when they are merely 1-2” tall as seen at left. The flower scape ultimately stretches to 6-8” tall as well and terminates in what appears like a shepherd’s crook, with the flower dangling from the center of the crook (see image below of Galanthus elwesii). When the flower initially emerges from between the leaves, the bud is held upright and is enclosed by a protective leafy bract or spathe. The spathe consists of two modified leaves called spathe valves and two transparent membranes. The spathe valves are located on either side of the flower bud and appear as slender green lines, as seen in the image above.
The two transparent membranes are connected to the spathe valves and wrap around the bud. As the bud expands, the membranes split open and fall away, while the 2 spathe valves elongate and curl downward, forming the ‘shepherd’s crook’, as the image of Galanthus elwesii depicts at right. As the spathe valves elongate, the flower bud transitions from an upright bud to a dangling flower, located near the center of the spathe valves. An incredible ‘dance’ and fun to watch evolve if time permits!
The compressed growing period pressures the genus to produce as many carbohydrates as possible for generating seed and developing new bulbs for the following year. Albeit small, these green markings aid in the production of the needed sugars! Interestingly, the foliage and tepals also contain small air-filled spaces that allow the flowers to tolerate subfreezing temperatures as they begin to bloom. The globe shaped ovary is located above the tepals, with the small black seeds maturing in mid to late May. The seeds have an attached lipid rich structure called an elaiosome, which not only feeds and attracts ants, but serves as a means of seed dispersal.
Another readily available species is the formerly mentioned Galanthus elwesii. The plant resembles its cousin in all aspects except it is larger with the outer tepals reaching an inch or longer in length. They are often the first species to emerge and feature green markings on both the upper and lower ends of the inner tepals. They can even be connected, as seen at right. The larger outer tepals results in a flower upwards of 2” in diameter when fully open! The species honors the British botanist and entomologist Henry John Elwes (1846-1922), who came across a mass of large flowered Snowdrops in 1874 while botanizing in the mountainous regions near Smyrna, Greece. In 1875, the English botanist Dalton Hooker (1817-1911) honored Elwes with the species epithet. Interestingly, the plant that Elwes found was actually a previously described species named Galanthus gracilis and Hooker’s species name was used to describe another, as of yet unnamed large flowered species! 
Another delicate and very attractive species is Galanthus ikariae. Named by John Gilbert Baker (1834-1920) in 1893, it is native to several Greek islands in the Aegean Sea, including the island of Ikaria for which it is named. If the island’s name sounds familiar, it is named after Icarus, who in Greek legend escaped from King Minos by fabricated wings from feathers connected by wax. When he flew too close to the sun, the wax melted and he fell to earth. Legend has it he was buried on this island that bears his name! This species bears smaller pendant flowers to 1” long and a single green mark on the tips of the inner, bi-lobbed tepals (pictured at right). Often, this green mark will extend half way or further up these tepals. The foliage is glossy and more attractive than the mat-green forms, growing to 6-8” tall. Not ideal for plugging into turf since the reflective foliage does not blend well with turf grass. In the wild, the plant is often found in river valleys, growing with Cyclamen hederifolium in deep humus rich soils. It has also been found in upland gravely soils in scrubby growth. The plant is somewhat less winter hardy, but I have not had any issues in over 30 years of growing the plant. Unfortunately, it does not appear to naturalize as readily as other species.
With the chilly temperatures of winter well entrenched in our Gardens, evergreen foliage clearly plays an important role in providing interest at this time of the year. Conifers serve an important role in providing the bones for the garden, but there is still a need for detail plantings as we walk about our walkways and paths. One plant I have enjoyed using over the past 30 years for winter foliage and form, as well as for its ‘hot’ flowers come spring is the Italian Arum, Arum italicum.
Typical to the genus, Italian Arum grows from a tuber, with the sagittate or arrow-shaped foliage beginning to emerge in late September or early October and typically remaining attractive until the following June (photo at right was taken on February 10th). During severe winters, the foliage can scorch if located in an exposed location, but fret not as it will be refreshed with new foliage come spring. The straight species features glossy, deep green foliage or foliage with white splotches while the previously mentioned subspecies is laced with white venation. The leaves usually grow to 12” tall by 6-8” wide, but can be larger if conditions are ideal. The foliage certainly provides great winter interest, but come spring, it is the flower that makes the plant all the more fascinating!
Arum flowers are termed protogynous, whereby the female flowers mature first and are no longer receptive to pollen when the staminate flowers mature and begin to release pollen. This staged maturation prevents the flowers from self-pollinating, resulting in inbreeding depression. To further aid in pollination, the male flowers are thermogenic, whereby they actually go through periods of releasing heat and can become upwards of 50 degrees warmer than the ambient air! Initially, this makes little sense, until one realizes that the flowers are pollinated by flies and the heating of the flowers releases volatile chemicals that smell like rotting meat or even stale urine! None to worry though, since the odors are too faint to be noticed by the passing gardener. Attracted by the odor, small flies are able to push past the filaments of the staminode flowers in search of the source of the odor but, due the slightly downward orientation of the filaments, the flies are not able to escape. The filaments remain resilient against any attempts of escape for around 24 hours, allowing the incarcerated the flies to hopefully deposit pollen from a previously visited flower onto the stigmas. After one day passes, the stigmas become unreceptive to pollen while the staminate flowers begin to shed pollen and the staminode filaments become limp, allowing the pollinators to collect pollen as they move upward and out of the spathe tube. An incredible scenario!
