5 Reasons Why Your Plants Are Blooming Out of Season

Extreme weather seems like the culprit for countless garden issues, and unusual temperatures are usually to blame for plants blooming out of season. Unseasonably cold, warm, dry, or wet weather causes stress that can trigger flowering at the wrong time. Erratic temperature fluctuations are also a major reason for trees and shrubs to produce floral buds at the wrong time of year.

Flowering is initiated by hormones called phytohormones, including gibberellic acid (GA), florigen, cytokinin, auxin, and ethylene. All complicated botanical jargon aside, these hormones help floral buds develop, open, and grow. If light, temperature, or moisture conditions are altered, or if the plant is exposed to sudden stress, the hormones may not send flowering signals at the proper time.

Spring-blooming shrubs sometimes flower out of season, so it isn’t necessarily something to panic about. But if you’ve noticed your azaleas showing up in the fall or forsythia blooming five months early, here are some potential reasons for the unseasonable blossoms, plus preventative measures you can take.

Why Are My Plants Blooming Out of Season? 5 Possible Reasons

Strangely hot or cool seasonal fluctuations can trick our bodies into thinking it’s a different time of year than it actually is. Plants are equally befuddled by seasonal variations. They can bloom out of season when these unusual conditions cause disruptions to their natural rhythms.

Unusually Warm Fall Weather

Autumn is traditionally a chilly time of year when plants slow down on growth in preparation for winter dormancy. But if the fall weather is unusually warm, many spring-blooming perennials can get tricked into thinking it’s spring. The higher fall temperatures mimic spring warmth after frost, which triggers early flower bud development. If this happens, your shrubs and trees may not bloom next year because they have already exhausted their resources.

Many species have chill hour requirements, which means they need a certain amount of cold weather to transition into winter dormancy and prepare for spring bud break. Cherries, pears, crabapples, and azaleas are common examples of perennials that can miss out on their chill requirements during an unseasonably warm autumn.

Luckily, if only a few blossoms have opened on warm days, the rest of the buds should remain dormant as long as the weather cools back down. 

Prevention: There is little you can do to cool off the fall weather, but you can ensure consistent moisture and temperature-modulating mulch over the soil to keep roots cooler. In warmer climates, plant species with lower vernalization (chill hour requirements) so you don’t have to worry about missing out on spring flowers and fruits.

Large Temperature Fluctuations 

Moving from an Arctic winter to an Equatorial summer would be a drastic change for anyone. But this big shift is especially shocking for a plant that is genetically programmed to undergo certain processes at specific times of year. Sudden temperature swings from extreme cold to extreme heat, or vice versa, can trigger plants to bloom out of season. 

If the weather in March is strangely warm, buds may break prematurely and start flowering. But if April brings unexpected late frosts, those buds and blooms will die before they can fruit. 

Plants need time to acclimate to big changes, so any drastic shift in weather will disturb their natural cycles. Again, there is not much you can do about the weather. However, you can help insulate your garden to prevent erratic fluctuations.

Prevention: If you see unexpected extreme lows in the forecast, use frost blankets, row fabric, or other cold weather insulation to buffer your plants against the chill. In extreme heat, consider shade cloth and extra irrigation.

Extra Cold Nights

A sudden cold snap is detrimental to most tender annuals, but it may not be as problematic for flowering perennials. The damage is most notable on plants that are already flowering. The blossoms may shrivel and fall before they are pollinated. But if buds have yet to break, a random frigid spring or fall night shouldn’t do much damage. 

Prevention: Keep an eye on local temperatures with your own weather center. Always have frost protection ready to roll out. If some species are already blooming out of season, you can use overhead irrigation as a last-ditch resort to freeze a protective water shell around the blooms. 

In the evening before temperatures dip below freezing, turn on sprinklers and allow the flowers and branches to fully soak. This method will create a surprising amount of ice insulation that can preserve the interior cells from freezing and bursting. However, if the freeze is prolonged, it will kill the buds and blossoms. Thus, you should only use this tip if you expect a brief and sudden frost.

Alternatively, some particularly dedicated growers will individually wrap breaking rose buds or other high-value shrubs to protect each blossom.

Physical Damage and Improper Pruning

Severe damage to bark, branches, or leaves can cause major stress for any species. If a large branch falls, or a tree’s bark is severely scarred by animals, the plant may bloom out of season or fail to bloom at all.

Improperly timed pruning can also cause physical damage that allows diseases to take hold, or stimulates unseasonable growth. When you cut back fall shrubs, it may promote new stems, shoots, and buds to emerge. This tender new growth is particularly vulnerable to frost damage and can significantly affect flowering in the following year.

Prune most fall-blooming shrubs during dormancy in late winter. In contrast, prune most spring-blooming shrubs after they finish flowering. If a plant blooms out of season, it’s usually best to wait to prune it until the correct time of year to help it get back on track.

Prevention: Always take special care to ensure clean cuts when pruning, and to treat diseased limbs as soon as possible. Wrap young saplings or sick specimens to protect from animals like browsing deer or woodpeckers. If there is a major storm, remove any dangling or loose branches to prevent shredded bark and diseases.

Prolonged Drought Conditions

Water stress can cause all types of issues in the garden, most notably a lack of flowers and fruit, or premature flowering and seeding (also known as bolting), which can ruin a crop. Drought-induced bolting is most common in annual species, but a lack of water can also confuse a plant into thinking it is a different time of year.

For example, lilacs and crabapples usually bloom in the spring, but trees exposed to long summer droughts may bloom unexpectedly in the fall. Researchers at the USA National Phenology Network track these changes and note major upticks in unusual biological timing of plant and animal events in recent years. 

Most experts agree that drought-induced out-of-season blooming is a sign of plants trying to conserve energy. After exposure to prolonged water stress, they move into dormancy that is similar to what they might do in the winter. Flowering species may put out a last-ditch effort of blooms before moving into a dormant state.

Prevention: Maintain seasonally consistent moisture throughout your garden and orchard. Drip irrigation and timers or clay pot irrigation, like ollas, are ideal for watering while on vacation outside of cold seasons. Reduced precipitation is increasingly common across most of the U.S., so it is extra important to keep your perennials hydrated throughout the year. 

Some gardeners mistakenly stop watering in the autumn, which can stress your trees and shrubs if fall rains are still several weeks off. Mulch is also vital for moderating soil moisture levels and conserving water during drought.