Unlike perennials, annuals do not come back from season to season so there is no reason to leave these in the ground. Pull them up, roots and all, and add them to your compost pile. Remove weeds and leaf debris. These are common places for diseases and pests over winter.
Remove Most Annuals
In general, these plants are easy to spot because after the first hard frost, many of them, including impatiens, begonias, and coleus, have withered and turned brown. If the spent foliage and blossoms on these plants are free of mold and disease, we put them in the compost pile.
Annual cleanup
Remove all of your summer annual flowers, including their seed heads, from your flower beds. (Throw these in your compost bin.) This does more than save you time next spring. Leaving annuals in your beds over the winter will invite pests and disease as the plants decompose.
CORVALLIS, Ore. – As fall approaches, consider letting some of your annuals go to seed. If the winter isn't too harsh, they may pop up next spring. Annual plants are inherently programmed to set seed and die in one year.
You can put them in a garage or shed that gets cold but doesn't freeze, ever. They will over-winter as live but semi-dormant plants. Keep the soil just moist, not letting the potting medium shrink and pull away from the pot edges.
Annuals typically flower and bloom in the spring and then wither and die around autumn. Unlike perennials, annuals do not regrow the next season—at least not from the same root. Instead, annuals must be replanted each year—or, in some cases, the seeds left behind may successfully sprout new plants.
Winter Protection Techniques
If possible, find an area in the garden that you can dig up, and sink the pots into the ground so their roots will be insulated by the surrounding soil; then mulch heavily with straw, shredded bark, or leaves as you would other plants.
Many annual plants can be brought indoors over the winter as houseplants. Another method is to take cuttings of your favorites such as coleus or impatiens, rooting them, and then potting the cuttings to bring indoors for the winter. Many of these plants can root very simply by placing the cutting in a glass of water.
Store your flowerpots out of the elements, if possible.
Ideally, you'd store them someplace that stays above freezing temps, like an attached garage. That way, pots that are vulnerable to freeze damage and breaking (like terracotta pots and ceramic pots) are less likely to crack and break.
After zinnias flower, cut off the old flowers (a process called “deadheading”) to encourage more flowers to form. Zinnias are annuals and will die with the first hard frost of fall. If you want them to reseed, let the last flowers of the season mature fully and scatter their seeds.
True annuals and plants that we grow as annuals (considered tender perennials in southern regions) cannot survive cold winter temperatures. But there's no need to say farewell to these plants forever! Many “annuals” can be brought inside, even tender plants that need a winter dormancy period.
If you are equipped to compost, your annuals will decompose beautifully for your spring garden. Unless your annuals, both flowers and/or vegetables, died from some sort of disease that could spread to next year's plantings, we recommend using them as “greens” in your compost waste stream.
Annual flowers grow for one long season, often into the fall, then die with the onset of freezing weather. With perennials, the above-ground portion of the plant dies back in freezing weather, but re-grows from the base and rootstock the following spring to bloom again.
Simply put, annual plants die in the winter season so you must replant them every year, while perennials come back every year so you only plant them once.
Annuals are structured to freeze and die with cold weather. Their goal in life is to save their offspring (seeds). Annual plants pull water from their seeds before winter comes; therefore, when the low temperatures come, there is very little water to freeze, swell and rupture the cells within the seeds.
One obvious sign of dead floras is mushy and fragile stems plus roots. Once a plant has reached this stage, no home remedies will save it.
The short answer is that annuals don't come back. Plants that flower and die in one season are annuals—although many will drop seeds that you can collect (or leave) to grow new plants in the spring.
Mulch Is Good. Adding a layer of straw, wood mulch or rotted leaves to the soil surface in containers will help to provide extra insulation from cold. Water Is Important. Though dormant ornamental plants don't drink much water, you want to keep an occasional eye on soil moisture, especially when there's been drought.
If you leave the soil in your containers and moisture gets in the soil, the soil can freeze and expand, damaging your pots. Even resin (plastic) pots can get freeze damage and crack open. I learned this the hard way when one of my resin flowerpots cracked down the side, like a man splitting his pants. Oops.
Wrap pots in burlap, bubble wrap, old blankets or geotextile blankets. It isn't necessary to wrap the entire plant because it's the roots that need shielding. These protective coverings will help to trap heat and keep it at the root zone.
Your annuals need lots of sunlight in order to survive the winter season, and so placing your plants in the brightest spot of your home will ensure they thrive. A windowsill that receives plenty of bright light will do!
Once finished blooming, annual flowers can easily be coaxed to continue blooming throughout the entire growing season by a simple process called deadheading― pinching off spent flowers.
Actually, both! Most marigolds are annuals, but a few are perennials. Marigolds self-seed so they may appear to be a perennial when in reality, they are just coming back from seed.