Ornamental Garden Calendar For March

By: Kimberley Pacholko


There may still be snow and cold weather in the forecast but it is time to get out in the garden and begin pruning many of your trees and shrubs before they bud up. If the weather cooperates it is also a good time to begin dormant oil applications and several other garden tasks. Try not to walk on wet soils. I know this is difficult this time of year but heading out to prune in the mornings or colder days when the soil is still frozen is better for your soil health. Following is a list of tips and tasks for the month of March. Note: these times are approximate and can vary depending on the weather and on your specific hardiness zone. The zone I write from is a zone 6, adjust your dates accordingly.

Trees and Shrubs

For all trees and shrubs prune out dead, diseased and damaged branches (DDD). Also prune out any crossing branches and water sprouts.

  • For many ornamental trees and shrubs, March is also a great month to carry out other pruning duties like thinning, and pruning for size and shape. Pruning during dormancy is an absolute must when carrying out extensive or more severe pruning like coppicing (cutting the plant back to the ground). Check out this article When To Prune Trees, Shrubs, Roses and Vines for more information about which plants can be pruned now.
  • Hold off pruning spring flowering trees and shrubs like forsythia, flowering quince, lilac, rhododendron, azalea, beauty bush, mock orange, red bud, flowering dogwood, firethorn, Japanese snowball, magnolia, viburnum, honey suckle, daphne and others, until after they are finished flowering. With the exception of dead, diseased and damaged branches which can be done now.
  • Hold off pruning evergreens until they begin actively growing, with the exception of pruning for winter damage, disease or insect pests nest sites.
  • Scout for and remove tent caterpillar webs.
  • During dry weather prune out cankers and diseased wood on any trees or shrubs affected by fire blight (prune these areas back an extra 30cm (1′) from the diseased material.
  • Examine the underside of viburnum branches looking for any egg laying sites of the viburnum leaf beetle. They appear as rows of small bumps 1-2mm in diameter (between the size of a pin head and a match stick head). The bumps are brownish-black. Prune off these areas and destroy.
  • If the weather cooperates you may get a chance to start applying dormant oil spray to some of your ornamental trees and shrubs to control over wintering insects and fungal diseases. The temperature must remain above 5 degrees C for at least 24 hours with no rain in the forecast. Not all trees and shrubs are tolerant of dormant oil like evergreens, maples, redbuds, hickories and walnut trees which may be damaged by the spray. A few exceptions are when spraying pine, spruce and euonymus for scale, the oil should only be applied at the lightest dilutions possible and leave out the Sulfur. 
  • Leave your winter protection in place until April as March typically still has freezing temperatures.
  • Check your yews for any signs of mealybugs. Prune out badly infected branches and hand remove any you find using a cue tip dipped in rubbing alcohol.
  • Scout for sponge moth aka. gypsy moth, egg laying sites and scrap them off and destroy them.
  • Be on the look out this month for any tip dieback on junipers that is the result of Kabatina blight.

Perennials

  • To help control iris borer clean up and destroy the old foliage before new growth begins.
  • If the weather cooperates you may be able to begin dividing summer and fall blooming perennials. Typically though the soil is still to wet and it is best to wait until April.
  • Ornamental grasses can be cut back once new growth begins.
  • Clematis may be pruned at this time, on a dry day, with no rain in the near forecast. Type C (group 3) clematis can be prune back to a healthy pair of buds about 30cm (1′) from the ground. Type B (group 2) clematis are pruned very lightly, pruning off only broken or diseased stems.

Miscellaneous

  • Dormant mail order plants should be unwrapped immediately. Keep the roots from drying out, store in a cool protected spot, and plant as soon as conditions allow.
  • Clean, oil and sharpen any tools not done last fall at seasons end.
  • Towards the later part of the month, if the weather cooperates you may be able to get started on some of your spring cleanup like raking lawns and cleaning up plant debris from last season. 
  • Apply sulfur to the soils around acid-loving plants such as azaleas, rhododendrons, hollies and dogwoods.
  • Do not work wet soils. 
  • Winter urn arrangements can be disposed of. Clean the urns and remove any over wintering insects or eggs (the underside of the rim is a great hiding spot).

Photo credit: photo taken by the author.

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