Six weeks have long passed since Punxsutawney Phil, the world-famous groundhog, emerged from his burrow and saw his shadow – but where is spring?

Robins have been observed to be back for a while now, a sure sign of spring’s arrival. And the Forsythia bush buds are just waiting to burst into a mass of yellow blooms, another indicator that spring is here. The appearance of crabgrass in the lawn is also said to be a predictor of spring.

These old wives tales are known as phenological signs (using annual/seasonal cycle of plants or animals to tell you when something else is soon to occur). The word phenology is derived from the Greek word phaino meaning “to show” or “to appear”, and is the study of seasonal change and timing of climate changes.

Although the indicators may be arriving, the weather has not been cooperating. It has been for quite a while now that local gardening folks are getting antsy to grab gloves, dust off their trowels and begin work outside.

The best way to know when the proper time has arrived for spring planting is to check the soil temperature. Bookmark the site http://extension.agron.iastate.edu/NPKnowledge/soiltemphistory.html to keep an eye on Iowa’s soil temperature by county. Avoid planting your garden too early, as seeds will not germinate in a soil that is too cold. Seeds can also rot if planted in cold, wet soil.

Most cool season vegetables need soil temperature of at least 50 degrees before planting. As soon as the ground can be worked, sow early “cool-season” crops such as lettuce, cabbage, cauliflower, broccoli, Brussels sprouts, and onions immediately after preparing your garden plot. Each vegetable has an optimum soil temperature range, so be sure to check the seed packet before planting.

Planting a garden is not hard, but without careful planning, your plants may perform poorly.

Did you know? To avoid soil compaction, do not work in your garden when the soil is wet. If you walk in the garden and soil sticks to your shoes or shovel – it is too wet to work. Wait until a ball of soil crumbles in your hand – that is when the moisture level is just right for planting.

Horticulture Questions? Contact McCormick at yvonne@iastate.edu for information or advice.