Update on 2023 Planting Recommendations

For the Northern Philly ‘Burbs

This is an update on a recent post, as promised, albeit a little late.

As I write this on 5/15/23, gardeners in the Mid-Atlantic are bracing for an unseasonably cold night on Wednesday. The original post (written on 5/4) included this remarkable graphic from a long-range weather model, which was a kind of a cautionary admonition:

The model was saying “Hey, don’t get too cozy with this idea of an early summer, because there is a chance that some unseasonably cold Canadian air will sneak well into the Lower 48 around May 17.”

So here is the same model’s updated idea for 5/17, from today (5/15):

Despite a few obvious differences, it is amazingly similar to the idea from over ten days ago. That kind of consistency is rare — and, to be honest, I did not expect it. If the feature persisted, I expected it to moderate, so that maybe, perhaps, worst case, we might be looking at a couple 45 degree nights this week. I.e., no big deal.

Nope. It went the other way. The forecast for Wednesday evening in my backyard is now 39 degrees! That is very cold for mid May in these parts. Another couple degrees and we might have to look at the F word (frost). And that would create an emergency situation for gardeners across the region, many of whom have gone ahead and planted sensitive plants early.

My gut tells me that we won’t see any frost in the Philly ‘burbs, and most garden plants will come through this without too much damage. But many folks in the Lehigh Valley probably will see frost, as the winds decouple and radiational cooling drives temperatures into the mid 30’s. And that indeed is bad news for the tomato plants.

If you transplanted sensitive plants into the garden, plan on covering them Wednesday night (and possibly Thursday). Be sure to water them well on Wednesday afternoon, as hydrated plants handle cold air better. If you still have sensitive plants in pots, leave them there until Friday — this is no longer the tradeoff type situation that I have discussed here and elsewhere, where it can make sense to plant stressed or rootbound plants despite some chilly temperatures. They are better off in pots until Friday.

So warm weather growing season is on hold this week. The theme for the week is to avoid further unforced errors, and minimize the impact of those already made. It will be a long summer, and there will be plenty of time for ripe tomatoes and crispy green beans ...after this week.