Gardening Notes For March

March can be such a finicky month!   Two 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!  Long range predictions are for average spring temperatures, but it never hurts to start the spring gardening chores early!  Keep referring to notes of 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 actually yielded better results!  

Things to do:

  • Remove leaves and winter mulch from early sprouting perennials and bulbs.
  • Finish, or maybe 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 hybrids early so the browning foliage does not distract from the flower display.
  • Prune!  Finish removing up to 1/3 of the older stems of, Lilacs, Kerria, Forsythia, Slender Deutzia, Weigela and other multistemmed flowering shrubs.  For Hydrangeas macrophylla, remove a few of the oldest stems, while Purple and Golden Smoke Bush should be cut back to 6-12” for 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.  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 become.
  • Cut and remove shrub stems that may have been broken during winter storms.
  • 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 branches to bring inside for forcing. 
  • Prune shrub roses back by about 1/2.  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.
  • 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 the air spaces and destroy the soil structure.
  • Edge bedlines and lightly remulch bed areas.  If the beds were mulched last year, only 1” of new mulch should be needed unless there was significant erosion. 
  • 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 (now reclassified as Plectranthus scutellarioides), you may wish to take cuttings and start new, stronger plants to move outdoors for summer display.