Focus on Flowers

Christopher Morley once said ‘April prepares her green traffic light and the world thinks GO.’  Green, in all of its shades, is the color of the month. The colors of the evergreens that anchor the landscape through all of the seasons now provide a backdrop for the early spring bulbs. The herbaceous perennial Hellebores, are flowering now too, and have leathery dark evergreen foliage, but need to have any winter-damaged foliage removed to look their best. The perennial groundcover, Vinca, also has evergreen foliage that provides a glossy foil for its little periwinkle blue flowers in mid-spring. Cicely Mary Barker (1895-1973) is well known for her flower fairy illustrations and poems. Here is her song of the Periwinkle Fairy: 
            In shady shrubby places,
            Right early in the year,
            I lift my flowers’ faces
            O come and find them here!
            My stems are thin and straying,
            With leaves of glossy sheen,
            The bare brown earth arraying,
            For they are evergreen.
 Evergreen leaves and needles provide the deepest notes in the spring symphony of greens. They complement the delicate freshness of the filmy green haze that is first seen on deciduous trees and shrubs followed by the varied hues of emerging perennials and the textured tones of the unfurling ferns and hostas. 
This is Moya Andrews, and today we focused on spring greens.

April is a month when gardeners long to plant but as T.S. Eliot said, it is “the cruelest month.” Warm days are often interspersed with freezing temperatures damaging over-eager plants that set their buds too soon. Over eager gardeners can also make mistakes. An exemplary gardener, Thomas Jefferson was born on April 13th in 1743 and he died at 83 in 1826. He spent 60 years developing the gardens of his estate at Monticello in Virginia, and he kept meticulous garden records. In his era all plants were open-pollinated so seeds could be gathered to grow the plants for the following year. 
Today many of our vegetables and flowers are hybrids, and their seeds don’t produce new plants. However, gardeners can still find sources for seeds from heirloom plants. Many of our annual old fashioned flowers such as larkspur, hollyhock, cleome, celosia and love-in-the-mist may self seed in our gardens and this is another reason not to begin digging in our flower beds too early. Jefferson’s records helped him to learn more about the patterns of growth during the seasons in his garden. Yet he never felt he knew enough, because towards the end of his life he wrote, “Even though I am an old man I am still a young gardener.” Young as well as old gardeners are important in April, but whatever our age and experience, this month we must be cautious.
This is Moya Andrews and today we focused on the cruelest month.

When we are awaiting the beginning of gardening season in early spring, we sometimes have periods of cold where tender plants, such as the emerging perennials in our gardens, are at risk.
Temperatures, even those that remain above 32F degrees, may still damage plants. When they do, it’s called “chill injury.” However, if the temperature that has been warmer than freezing suddenly hits 32F degrees or below, the effect that is triggered in the garden is called a frost.
If we have vulnerable plants in our early spring flower garden and the forecast predicts frost, we need to take protective action.* Actually, any prediction of temperatures even close to freezing should be cause for alarm.*
A visible white coating, or freezing temperatures in the absence of visible signs, will hurt vulnerable plants because low temperatures cause both dehydration and disturbance of cell membranes deep within cell tissues. This results in blackened, lifeless leaves and stems.
Different parts of the garden, such as hollows or areas near walls and hedges and southern exposures, may vary in temperature from other parts of a garden.
Remember the danger of sudden spring frosts and wait to set out your tender annuals, and protect vulnerable perennials coaxed out too early by warm days. Plants grow more quickly when temperatures warm more and stay warm. Don’t plant too early!
*Cover plants at night especially. But remove covers once it warms up again the next day.
**Anything below 35F, when it is still and there is no cloud cover.

Air temperatures that hover just above freezing for a prolonged period of time in the spring can kill most tender plants if they’re set out too early. So if you set out your houseplants outdoors too early, even if it’s actually above freezing in terms of the air temperature, they simply can’t endure it after being accustomed to the warmth in the house.
All air temperatures affect plants, as it affects most of their physiological processes such as their absorption of water and nutrients and time of flowering, fruiting, and also seed production. Each plant species has its own critical air temperature, which includes the minimum and maximum temperatures between which a specific plant can continue to exist, grow, and/or thrive. There is the perfect temperature for it to grow optimally and the lethal temperatures, both high and low, when a specific plant will expire.
All these levels are also, of course, influenced by the individual plant’s stage of growth and development. Seed germination requires more warmth than vegetative growth as well, and optimum temperatures are different for both day and night.
The important point here is, of course, do not take risks by setting out your annual plants too soon. Always be cautious for it is better to be sure than sorry when considering when to plant outdoors in the spring.

The weather in our flower garden has to do with local atmospheric conditions: hot and cold; wet and dry; calm and stormy, and so on.
Climate refers to the region’s atmospheric conditions and predictable events for that region or particular place. The US Department of Agriculture (USDA) divides North America into 20 separate zones, and the zone we garden in determines the plants that we can grow.
But as well as the average highest and lowest temperatures that occur in our specific zone, many other factors affect our weather and the perennial plants we can grow since perennials need to winter over.
Frost dates are very important. Gardeners need to know the average dates of the last frosts in the spring and the first frosts in the fall in their area. The date of the average last frosts is crucial so that we know when it is safe to set out our tender annual plants, which would be damaged or killed by a frost. The date of the last spring frost for a zone is like a marker that allows gardeners to schedule gardening efforts.
Of course, there is a difference between usual and average frost dates. We also need to establish how many frost-free days there are in our climate, as this defines our growing season and our options about what we can grow.
There are also micro-climates within our personal gardens: places, for example, where there is more sun, less wind, or more shelter for the plants.
REFERENCE: Gardener’s Guide to Frost: Outwit the Weather and Extend the Spring and Fall Seasons, Phillip Harnden, Willow Creek Press (2003).
NOTE: It is best for gardeners to err on the side of caution when planting spring annuals. If a late frost comes, the plants will be killed if they are planted too early. Annuals do best when the soil has warmed enough so that they can immediately begin to grow in their new location. In my Zone 6 Indiana garden that is usually around Mother’s Day.