It’s been a long time since school for me, and I was never good in science, so forgive me if I’m asking a fifth-grade question.
When grass and flowers die at the start of winter, they’re dead, right? So how do flowers and grass come back in the spring? I assume trees just hibernate or something.
Title should read “What causes the flowers to come back every spring?”
"Many perennials lose the parts of their plants that are exposed as the temperatures drop. The roots in the ground move as much of the the water in their tissue’s cells into the surrounding ground as possible. With less moisture in the plant’s cells, a certain amount of freezing and thawing can occur without rupturing those cells.
Also, sugars and salts in those roots act as a natural antifreeze. By lowering the freezing point of the water in the plant’s cells, it allows them to survive lower temperatures."
The sorts of grass that we use as lawns in the U.S. usually doesn’t die in the winter months; it goes dormant. If an area on your lawn doesn’t turn back to green in the spring, then it probably did die over the winter. (Also, grass will go dormant during drought conditions, even in the summer.)
Annual plants die every year or so. The species survives by producing seeds that can grow new plants every year. Some of them complete the cycle in less than a year, and another kind of plant does it in 2 years. Obviously annuals will be limited in size because each plant completes it’s life cycle in a short time.
Putting @TriPolar comments about “Annual” plants together with what @Jackmannii almost said, “perennial” plants sacrifice parts of themselves each winter while the overall plant survives living in slow motion until spring when it regrows fresh leaves and flowers for the next warm cycle. So sort of vaguely like animals hibernating. If you imagine animals having limbs fall off and regrow fresh each year.
Trees are perennial, but so are many common garden plants and flowers.
Not that it matters terribly, but what I quoted about perennials closely matches what you just posted, i.e. above-ground tissue being lost to cold while the less vulnerable rootstock/corm/tuber/bulb survives. No “almost” about it.
Some perennials do maintain viable above-ground tissue even through harsh winters and in the case of hellebores for example, push buds and flower during mild spells.
Some of them can get to be 10-15 feet, though.
Fixed.
Yeah I didn’t say that as well as I might have. Sorry.
You gave the full story on perennials and Tripolar on the annuals. But nobody explicitly brought out the idea that plants come in those two broad classifications that have very different winter survival features. That was the “almost” part I tried, and failed, to clearly point to.
This little tidbit about the Molecular Genetics of Annual Plants is interesting:
" In 2008, it was discovered that the inactivation of only two genes in one species of annual plant leads to the conversion into a perennial plant. Researchers deactivated the SOC1 and FUL genes in Arabidopsis thaliana , which control flowering time. This switch established phenotypes common in perennial plants, such as wood formation."
Let’s start here.
By “grass” you mean a turf lawn, like what your neighbors mow? If so, then no, not dead … just dormant, which is sort of like a bear hibernating.
By flowers, you likely mean the ones that bloom for weeks or even months at a time: pansies, zinnias, etc. Brightly colored, long bloom time.
These are the annuals mentioned above: they live a year or less. Those ARE dead each winter.
They come back by re-seeding (or by your gardener buying more at the big box store) to start the life cycle from scratch.
Or like a deciduous tree that has dropped its leaves. The tree is alive; the leaves are disposable and will be regrown.
I live in Houston, TX suburbs. Our growing zone is 9A. Depending on the severity of the winter, many so called annuals behave like perennials. Plants like petunias don’t die back but remain and grow back stronger in spring.
Yeah, there’s a blurred line between annual and perennial - many plants that are technically perennials can still flourish as annuals outside of their preferred climate conditions. Tomatoes and capsicums, for example (interestingly, also in the same family as petunias - Solanaceae seems to like this trick)
I suppose another way to look at @am77494 and @Mangetout’s observations just above is that in the wild, plants will “migrate” (spread new individuals actually) from their current best habitat poleward until they find themselves dying off each year from the cold and short growing season.
If they have a robust enough reproduction system that can create new reproducing adults in a single growing season they may become de facto annuals in that marginal habitat. And if they can’t quite manage that trick they simply aren’t found that far poleward.
Humans of course can plant anything anywhere for reasons both smart and dumb. And force it to grow or replace it when it just won’t / can’t.
Agree LSLGuy. This February, we had a 100+ year freeze event. Many of my annuals and perennials are dead from the freeze, but some are coming back from the freeze. The reason, I am bringing this up is that poleward migration of plants depends not only on the yearly weather but also the long term freak weather events
People try growing plants like peonies, lilac, cherries, etc - some may grow briefly but they don’t flower/fruit. Again this is in the Houston weather.
Another example of a plant commonly sold and referred to as an annual is Nicotiana alata - flowering tobacco. I was surprised this spring to see a couple of my plants regenerating from the roots in zone 6b after a minimum winter low of 9F, as I’d always thought it was a true annual. Nope.
Again - Nicotiana is in the Solanaceae - seems to be pretty much the party trick of that family to be perennial, but also reproduce in the first season, so as to function as an annual where required.
Yep, elevation is another thing - some of the plants we have been discussing are indigenous to places like Peru, where there are colder/warmer/wetter/drier microclimates due to elevation, exposure, etc.
Another thing that perennials-as-annuals can do is to reproduce quickly in a wet spring season, then if the summer gets really dry, survive as seeds, or if it’s not so dry, survive also as perennials