Posted on by tonytomeo

Environmental Factors Silently Influence Bloom

California poppy dramatizes favorable weather conditions.

Superbloom occurs only about once every decade or so. It is very unpredictable though. It can happen for two or even three consecutive springs. Alternatively, it may not happen for two decades. It can be as early as late February, or as late as late May. It can last one or a few weeks. Superbloom is as variable as the environmental factors that influence it.

Actually, all bloom relies on influence from variable environmental factors. That is how it knows how and when to bloom. It is also why many species are so irregular about doing so. Various species prioritize reliance on various environmental factors. Therefore, some may bloom early or late while others adhere to stricter schedules. It can get complicated.

Warmth is undeniably the most significant of environmental factors that influence bloom. Cool weather inhibits bloom, even as growth resumes at the end of winter. Then, warmth accelerates bloom, mostly during spring, but also into summer. Many species continue to bloom as long as the weather stays warm. Very few prefer to bloom during cool weather.

As mentioned, the influence of environmental factors can get complicated. Many species actually require sustained winter chill, or vernalization, to bloom well. It is how they reset their growth seasons to begin in winter. Peony is unreliable here because of inadequate chill. After unusually cool winter weather though, flowering cherry and lilac bloom better.

Humidity is another important environmental factor. Although it does not stimulate bloom for more than a few species, it can prolong bloom. Some flowers, particularly from humid climates, can desiccate with aridity. Conversely, even flowers from desert climates retain hydration better with humidity. Also, rain provides water for areas that lack any irrigation.

Species from mild but not tropical climates might rely more on photoperiod than weather. Poinsettia in the wild does not experience sufficient chill to distinguish winter. It monitors the photoperiod, which is the duration of daylight, instead. It knows to bloom when nights are longer than days. A few species use the same very consistent technique to bloom for other seasons.

Posted on by tonytomeo · 6 Comments

Vernalization Enhances Bloom And Growth

Unusually wintry weather enhances some bloom.

Some gardens continue to recover from the exceptionally wintry weather of last winter. Frost damaged some plants, and killed a few. Wind damaged trees. Excessive rain caused erosion and saturation. This collectively unpleasant weather inhibited some from maintaining their gardens. Yet, some plants that require vernalization are performing splendidly.

It seems like an odd juxtaposition. Bloom of some plants is so unusually robust amongst remaining weather damage. Some bloom is noticeably late while most is precisely on schedule. It is not so odd to the plants who seem to behave so oddly though. Whether they appreciate vernalization or dislike frost, they respond to the weather.

Vernalization is merely attainment of sufficient chill to convince plants that it is winter. Many plants that are endemic to climates with cooler winters appreciate such reminders. It initiates their dormancy and resets their respective schedules. They know that subsequently warmer weather initiates their growing or seed germination season.

Plants that are endemic to climates with mild winters are less reliant on vernalization. Some of such plants are vulnerable to frost. Canna are tropical plants from mountainous regions that sometimes experience frost. They die back harmlessly if frosted, and remain dormant until safely warmer weather. They react to chill, but do not require it seasonally.

Spring bulbs, forsythia and flowering cherries have already bloomed atypically boldly. Later flowering cherries, as well as purple leaf plum, lilac and wisteria continue to do so. Peonies are likely to bloom better than typical a bit later. They are rare locally because of their reliance on typically unreliable vernalization.

Some cultivars of apple and pear are likewise unreliable within locally mild climates. Those that normally perform well here may perform better this year. After early warmth to initiate bloom, stone fruit bloom can succumb to late frost. Last winter though, frost was continuous enough to delay bloom until after the last frost. Extra vernalization may instead enhance production.