Is summer finally over?

After the beach and barbecue days of last week, it’s becoming more autumn-like now. Global warming aside, it’s not unusual to have a summery spell in fall.

I’m not a serious recorder of weather, but I did note that the first week of November in 2015 had a few days when the temperature exceeded 20 degrees, and by Christmas there was still no frost in the ground.

Despite the blips this year, fall will progress.

Leaves are beginning their descent, and even though many plants are hanging in, they’re looking tired due to shorter days. It’s a signal for them to prepare for winter.

The other one is temperature, both in the soil and in the air. Either one or a combination of both is what causes a plant to react — to grow or shut down. Plants adapt well to the temperature changes providing it’s not extreme. It’s the sudden fluctuations that trouble them.

As air temperatures drop, the annuals are the first to suffer. Below ground where the soil will stay warm for some time, perennials will remain active until the ground almost freezes.

Providing the foliage remains healthy the plants are storing nutrients in their roots, bulbs, rhizomes and tubers in preparation for next year’s display. That’s also why we don’t remove foliage from springflowering bulbs until it dies back naturally.

Even with summer weather in late October, it’s not unusual to have already had sharp cold spells with a hard frost, sometimes as early as September. This can disrupt the natural progress of plants.

To reach their potential of full hardiness, plants like to acclimatize gradually to colder weather — I know I do. The perfect fall would be one where temperatures fall steadily and consistently, right into winter. When weather is unseasonably warm, it can stimulate fresh growth that won’t be able to withstand sudden cold.

When an early dip in temperature rebounds to summer levels, it can trick plants into thinking winter is over and it’s time to begin growing again. It can even affect spring-flowering bulbs like tulips and hyacinths that normally require an extended cold period before new growth begins.

There are sometimes a few that will tentatively stick their tips up from the soil before being buried in snow, but they’re usually fine and should still flower in spring as expected.

This is a problem for other perennials that are not as hardy, such as the zone six or higher plants we insist on trying to grow here in our zone five (I’m guilty). They often do fine for a year or more if the weather co-operates but they’re even more susceptible to fluctuating conditions.

The recent summer weather has influenced flowering shrubs, too. I heard from gardener Helen Bergstrom in Waterloo that her redbuds trees were blooming already, half a year early. This can also happen with shrubs like forsythia that flower in early spring. The buds are formed through summer and are set to flower in April or May. If some of them are confused about the season

and manage to flower in fall, they will not bloom a second time. Providing there are other buds that didn’t open, there’ll still be some spring colour, though less than usual.

In the end, there’s nothing we can do about the weather, and neither can the plants, but we can help tender ones by providing a protective layer of mulch.

Meanwhile, if you have plants flowering now, whether they should be or not — enjoy them while you can, because you know winter is coming.

To chat with local gardeners, share tips, pics, or discuss a summery fall, see Grand Gardeners on Facebook at www.facebook.com/groups/Grandgardeners/.