Plants could not proliferate as they do if they were as unintelligent as they seem to be. Actually, much of their activity would be considered quite ingenious if it could be observed in a more human perspective. From their exploitation of pollinators to their aggressive tactics for competition with other plants, the behavior of plants is obviously very deliberate and purposeful.
The life cycles of plants are on strict schedules because they are so reliant on the weather, pollinators and so many other environmental factors. They must also adapt to diseases and all sorts of other pathogens. Fire and grazing animals are problems for many, but advantages to most.
Most seed develops during summer and autumn. When they fall to the ground, they need to know to delay germination until spring to avoid frost and the likelihood of getting eaten. Seed of many plants, particularly those from more severe climates, germinate only after being "stratified" by a specific duration of cold weather. Such seed need to be artificially stratified by refrigeration in order to germinate any differently from their natural schedule, or where winters are not sufficiently cold.
Many seeds require "scarification" by digestion by animals that naturally eat them, or by the quick heat of a wildfire, to break or soften a hard outer coating that otherwise inhibits germination. Seed that need to be digested actually rely on animals for distribution. Seed that need heat want to be the first to regenerate after a wildfire, before competing plants recover.
Goldenrain tree, and many maples and pines, produce so much seed that even if less than 1 percent germinate in the garden, they seem to be prolific. However, for more reliable germination of a majority of seed, they should be scarified. The seed of many pines that crave fire can be heated briefly in an already hot oven to simulate fire, just enough to heat the seed coating without roasting the seed within. Some people actually prefer to spread them on a piece of paper, then burn the paper. Seed that only need their hard outer coating to be damaged slightly might need only to be sanded lightly on sandpaper. I actually prefer to rub my canna or Heavenly bamboo (nandina) seed on a brick or bit of sandstone.
Flower of the Week: Canna
Although not directly toxic, canna has a unique reputation for lethality. Its spherical seeds are so hard that they were historically used as shot. Many victims are now pushing up daisies. Those who survived were pulling out cannas.
Old-fashioned varieties that get up to 6 feet tall seem to be at least as popular as shorter modern varieties that get less than half as tall, probably because their bold foliage is as appealing as their colorful but awkwardly structured flowers. The big leaves can be cool green, rich reddish bronze or variegated. Red, orange, yellow, pink or rarely white flowers that bloom from summer to autumn are striking amongst the lush foliage, but are too perishable to be good cut flowers.
Stems that have finished blooming should be cut to the ground to promote more colorful new foliage and bloom. Mature colonies of rhizomes can be divided while dormant through winter if they get crowded enough to inhibit bloom every few years.
Horticulturist Tony Tomeo can be contacted at 408.551.9931 or firstname.lastname@example.org.