May Two-Four

Garden Clippings for May 12, 2018

The Victoria Day Monday, May two-four weekend has always been Southwestern Ontario’s unofficial frost-free date.  In just a week, gardeners everywhere will be planting everything from Maples to Marigolds.

But here’s your warning:  don’t get too ambitious.  April has been the coldest on record and there are many plants that won’t enjoy the transition from a warm greenhouse to cold soil.

Trees, shrubs, perennials and evergreens will perform just fine if planted in cold soil, but many annual flowers and vegetable plants will balk at the thought of putting their roots into the cold earth.  This past Thursday temperatures in parts of Sarnia Lambton dipped down to 4 degrees C, and the weatherperson is not ruling out the return of similar cool evenings in coming weeks.

Pansies are the exception to the rule.  Pansies love cold weather and can be planted in March as soon as frost leaves the ground.  In the vegetable garden, spinach can be planted early, followed by onion setts and peas.

Lettuce, Broccoli and Cabbage are cool season vegetables and can be planted anytime during the month of May.  These crops don’t mind cold soil and can tolerate the occasional light frost.  If planting seeds, radish, carrots and swiss chard are also fine with planting in cool soil.

In the flower garden, snapdragons, nemesia, osteospermum and dusty miller are fine with cold soil.

All perennials are cold tolerant and don’t mind planting or transplanting in cold weather before the frost-free date.  But I prefer planting perennials in the fall when growth slows down.  The challenge with early spring planting of perennials is that plants are so small that its difficult to know what you are planting where.

But the vast majority of vegetable plants and annual flowers cannot tolerate frost and will not perform well if planted in cold soil.  Tomatoes and peppers, the mainstays of the garden won’t begin growing until the soil temperature is consistently warm.

If planted in cold soil, tomatoes and peppers will do nothing until soil warms up.  If weather is consistently cold and damp, they may suffer from root rot.  Likewise, many vegetable seeds won’t sprout until the sun warms them up.

Trees, shrubs and evergreens are not fussy about planting time and can be planted anytime the ground is not frozen.  Ditto for fruit trees and fruit plants.  And nowadays since most nursery grown plants are potted and already growing in their container, planting can be done anytime in spring, summer or fall.