It's now those few weeks in zone 5 where the exhaustion of winter combined with the excitement of a stocked garden center leaves one conflicted. Are you asking yourself, "Should I hold off planting and wait for the weather to be slightly warmer?", or resolving, "I desperately need to see some color. I'll take my chances". What to do?!
When planning early spring planting, I look at overnight lows in the 10 day forecast. Given the calendar, X day plus 10 without a freeze usually gives pretty good odds of plant survival. First, because you have 10 days of frost free weather, but perhaps more importantly, those 10 days close to freezing are good "hardening" days. Though there are no guarantees, and we do replace a few plants, it's a rule that has worked well over the years. Remember, these days were trending warmer!
The first areas I want to plant are the microclimates that are more forgiving. In my back yard, it's a sheltered area on which the boiler is on the other side of the wall. That spot always is a week or two ahead. You probably have an area or two at home that is advanced as well.
For our clients, we plant in the city first because all that concrete is now radiating that glorious spring sun, thus making the city a little warmer than our sylvan suburbs.
Today, I see a couple of freezing dips in that forecast, yet, that isn't stopping me from scratching my gardening itch. Certain plants will take a freeze, such as tulips and pansies. What you want to look for in forced tulips is emergent growth, with plants no more than 3 or 4 inches out of the pot. (Forcing is when the greenhouse pots the bulbs in the fall and chills them in a cooler over winter). If the bulbs are showing color, they are way too developed. The opposite is true for the pansies, you want larger plants with well developed roots. Flowers are nice but of lesser importance, as blossoms don't necessarily indicate strong roots. Besides, if a pansy freezes, the open flowers will burn-off with no harm to the plant. Take the plant out of the pot and look at the roots for development. If the plant resists coming out, that's a good sign of development right there.
There are some plants that can take a frost, but will need to harden first, so if you have the time and space, hedging your investment can pay off. These plants, such as nemesia, ivy, lemon cypress etc., will require vigilant effort covering or moving to avoid freezing to harden their resistance to the cold.
Our beloved hydrangea will take a freeze, but the beautiful mop heads will not. Open hydrangea flowers love 33 degrees and fail at 32 degrees. Of course, we buy the hydrangea for the flower and not the plant, so losing the color and leaving a green bush is disappointing. Did you ever have a bathing suit that the chlorine faded, leaving a functional but rather ugly suit? That's a frozen hydrangea!
If you want to incorporate all of these elements into a container composition, I suggest that you wait until you have that 10 day stretch and still be ready to cover if necessary. However, if you're ready to plant, identify an area or two and create you own spring display and get going!