Dwarf forsythia in Northwest Denver on April 6, 2013
Robert Frost was undoubtedly NOT thinking about Forsythia when he wrote his classic short poem, whose proper title is "Nothing gold can stay." I suspect as a good New Englander he was thinking of the golden sheen of willows, and the chartreuse shoots emerging from the ground everywhere in spring (and turning green in a few weeks)--or the chartreuse haze in the trees before they leaf out. But for Forsythias, "the early leaf's a flower" as well, and they are starting to be glorious right now! If you do not know the poem, do linger over it. If you know it well, you will linger all the more:
Nature's first green is gold,
Her hardest hue to hold.
Her early leafs a flower;
But only so an hour.
Then leaf subsides to leaf.
So Eden sank to grief,
So dawn goes down to day.
Nothing gold can stay.
Forsythia x 'Arnold Dwarf'
There is an ominous undercurrent to this poem, which explicitly refers to how quickly things decline. But in the case of forsythias, Coloradoans know that many years (it used to be most years) the flowers would rarely last more than a day or two before a sudden cold snap froze them. With lows predicted to drop to 20 in a few days, that may happen yet again to those whose flowers are emerging or fully out.
A cautious Coloradoan would cut branches tomorrow of any forsythias in the garden. The more branches you cut, the less likely the remaining branches you leave behind will freeze (don't ask me why--it's superstition I suspect)...
For many years one find Forsytha viridissima 'Bronxensis' sold locally from time to time. It has a paler flower and the plants are somehow more susceptible to frost. 'Arnold Dwarf' has a darker gold flower, and seems to do well, provided you have a spot where it can trail down gracefully. And I would put it in a cooler microclimate where it will not be coaxed into too precocious of bloom.
This more chartreuse shade of yellow is what I really think of in early spring. The Euphorbias have gotten a bad rap--this and the next have both been declared noxious weeds in many states. I have never seen E. cyparissius behave TOO badly in Colorado, certainly not in wild areas. It can spread rambunctiously in the garden, but so can violets and lots of other plants no one complains about. If you choose to let into your garden, do put it "between a rock and a hard place"--in some spot where you can control its spread and where it will not swamp smaller plants.
This is the culprit--public enemy number one! The weed police may put a placard on your door (and you may be put in stocks and pilloried) if you happen to have this in your garden. There was a time when this had naturalized a few hundred feet east of Boulder where it has been largely extirpated. But it can also be found sparingly in the foothills--at least in Jefferson and Boulder counties. Nurseries no longer sell this plant, and you would be hard put to find it. But I have to say, I am rather pleased a few dozen gardeners around the Denver area have retained this plant. Kids just love it (doesn't it look menacingly reptilian?)
Here you can see it's made quite a colony along the street in Northwest Denver. I haven't observed that it spreads unduly in places like this, and this garden has an no-water border where this is a welcome addition. I think it would be a shame if this old passalong plant disappeared entirely from Denver--especially this time of year when it's glorious golden hypanthia (that's the technical term for a Euphorbia flower, by the way) are so alluring! If you do choose to remove your plants, be sure to wear gloves and not get any of the milky sap on your skin and especially in your eyes. The sap can produce a severe dermatitis in some people, and juice in the eyes can be very painful, and potentially dangerous to your eyesight. In other words, exercise caution!
Oh well, if the weed meanies do get rid of the last of these, we can just recite Frost's old poem: "Nothing Gold can Stay...".