Early spring planting tips from a gardening meteorologist
Notwithstanding the current and recent deluges, planting time is fast approaching. I always like to keep an eye on the map of average temperatures over the past several weeks (shown to the right). It is a good rule of thumb for monitoring soil temperatures in the garden. As you can see, we have risen above the 40 degree mark and that signals the beginning of plant awakening in our area.
Most seeds need a certain minimum temperature for germination and this is a great guide for planting. As some of you have already shared, your early bulbs are already off and blooming with many more about to explode into masses of color. Isn’t it great to see! For those of us who struggle to get motivated about planting bulbs in the fall, now is payoff time. We will talk a lot more about bulbs in the fall as I encourage you to take advantage of a great early highlight in the garden.
This is a great time to get cool season veggies sown, like lettuces, if you have a plot or even just a pot. Temperatures around here climb pretty quickly this time of year so you have to move fast to take advantage of this window. If you are working in the garden, it is a good idea to wait at least three and preferably five days to work the soil after a rain like we are having. This is especially true if you have clay soil like most of us do. Work it too early after a rain and it will turn into a brick that very little will emerge from. Timing is going to get a little tricky as we are coming into a wetter period right now, so use our daily Capital Weather Gang forecast to plan ahead. The good aspect of the wetter weather is that the moisture deficits look likely to be a thing of the past and our trees and shrubs will be much better off.
Speaking of trees and shrubs, the buds are beginning to swell. For most trees this is not a good time to do any pruning as the sap is rising. However, it is a good time to take a good look at those trees and make notes of any branches that need cut back later in the season.
As for those most famous trees in D.C., the cherry blossom expert Rob DeFeo predicts peak bloom to be March 29-April 3. If you have a chance take a walk around the pool, it is heavenly. In fact, this year might be a good idea since next year marks the 100th year of their arrival from Japan and I am betting it will be swamped.
One more note on shrubs: If you are like me, there are times in the nursery where you see something that just catches your eye and you have to have it, but you don’t know much about it. I had Clethra shrubs last year that I swore were dead and about to pull up when lo and behold just a little more warmth and they had leafed out, strong as ever. Our beautiful crape myrtles are a prime example of shrubs that are very late to come out of winter dormancy, so be patient. If you are really curious you can scratch a branch and if there is a green layer beneath , you know the plant is still very alive.
This is also that time of year, when late season freezes can be a concern. As noted in my last post, some plants can take a freeze with minimal damage, like pansies, Lenten roses and early bulbs. However, if you have some early tender plantings that you are worried about on a particularly cold night, a sheet of plastic can be staked over the plants to take advantage of the warmth coming up from the soil. Hardware stores have big sheets of this used to cover floors for paint projects which work well. Just be sure to get it off the next day before the sun shines through or you could end up with plants wilted from the quick heat up. Another trick if you don’t have the plastic available is to wet the plants down. The physics of this is that as the water freezes it actually gives off heat and lessens damage. That is why you always see those oranges down in Florida during a cold snap with icicles on them; they have been sprayed to diminish the damage.
I will be back in two weeks to talk more about all the fun and games in the gardens as spring gets into full gear. In the meantime, I welcome all your questions! If I can’t answer them, I will get you the answer from some of our local experts.
Capital Weather Gang meteorologist David Streit is also an active gardener. He earned a certificate in landscape design from the USDA Graduate School and volunteered many years at the National Arboretum.