Maximizing microclimates

Here are the first daffodils I've seen this year (probably Narcissus 'February Gold'), along with some crocus, and the first scilla, or Siberian squill.​ These daffodils actually began blooming over a week ago, but I didn't get a photo until now. If you look closely, you'll see the reason for this especially early flowering: a concrete foundation in the background.

​Microclimates greatly affect the bloom time of spring bulbs because soil temperature is their main catalyst for growth. On sunny south-facing sites — like this photo — snow melts more quickly and the exposed soil warms faster, forcing bulbs to begin their spring push earlier. Throw in a masonry wall to reflect even more light onto the soil and transfer radiant heat down into the rootzone, and you have an ideal microclimate for forcing bulbs.

Planting the same, or similar, bulbs in a nearby shaded area — where soil temps are relatively cooler — will retard bloom time and considerably lengthen your flowering season for that particular species. (But never push the shade beyond reason; most bulbs require a certain amount of direct sun to rebloom reliably year after year.)

Winter's firmer grip

Hunting through some of my bloom photos from last year, I was struck by how much more advanced many of the flowers were then as compared to this year. I photographed 'Tete-a-Tete' daffodils in full bloom on March 8 of last year. Visiting the same garden a day later this year, there was nary a daffodil in sight.

Here's photographic proof: this is the same winter jasmine (Jaminum nudiflorum) in exactly the same spot at the New York Botanical Garden. The left half of the image (with the author's shadow) is March 9 of this year, the right half is March 8 of last year. ​

For those looking to draw some conclusion concerning climate change, I would point out that this is no more than yearly variation, but it does vividly illustrate how sensitive (and adaptable) plants are to average ​temperature changes. It would be wonderful to have another photo from when New York City was still truly USDA plant hardiness zone 6b (we are now 7b).

Crocus peak out

The first crocus I've spotted this year. These are on a south-facing slope near the entrance to the newly expanded native garden at NYBG. There's still snow on the ground in the shade, but here in the sun, spring has sprung.​

These look like C. tommasinianus 'Whitewell Purple'​.

Snowdrops

And here are the first snow drops (Galanthus sp.). We call them snow drops because of their flower's association with snow, but the generic name, Galanthhus, comes from Greek: gála "milk" and ánthos "flower". The flowers do look a bit like drops of milk, don't they?

This bunch is planted just inside Riverside Park at 101st Street. My neighbor, Mike McGuinness, tells me he planted them there years ago, and that the starts were from his mother's garden. How can you not love a plant with history and a good story behind it?

First bloom (witchhazel)

The first bloom I witnessed this year was not surprisingly a witchhazel, probably (Hamamelis xintermedia), the most common cultivar of which is 'Arnold Promise'. However, Dirr's Hardy Trees and Shrubs states that Chinese witchhazel (Hamamelis mollis) blooms earlier. I have never seen H. mollis for sale in local trade nurseries, and since it is one of the parents of the hybrid (H. japonica is the other), only a botanist could surely tell the apart. It seems likely however that this is the progeny and not the earlier-blooming parent.

Note: This specimen was located in Cypress Hills Cemetery, high on the terminal moraine that is a popular Long Island cemetery site (for its rising slope & prospect)​. Look closely and you will notice it is planted at the sidewalk terminus. Was this to keep strollers from wandering out into the roadway? Or did it just seem like an obvious sightline? Odd.