Stalled growth in winter months

Outdoor potted lettuce

Saturday, November 23, 2024

If you have noticed that plants seem to stop growing in the winter, whether indoors or out, you would be right.  Growth slows as temperatures fall and sunlight decreases.

Basically, plants become almost dormant when receiving less than 10 hours of daylight at cold winter temperatures.  For my latitude, daylight of less than 10 hours is from November 24-January 17 this winter season.  You can look on the weather channel to see when your daylight hits 10 hours.

When planting in the fall for winter crops, I try to get my veggies to full, harvestable size by November 24th when daylight hits less than 10 hours (I add 14 days to be on the safe side for the cooler temps of fall and less daylight than in spring to the seed package Days to Harvest time).  They will remain basically this size until the end of January, when they begin regrowing.  If growing in a greenhouse, the warmer temperatures will help plants grow, but at a much slower rate than during longer daylight times.

I have full size a couple of varieties of chard, Chinese pink and Utah celery, Giant Blue Feather lettuce, tatsoi, Giant sweet mustard, parsley, cultivated dandelion, sorrel, and purple sprouting broccoli.  I started lettuce in September but it still isn't to full size. The varieties that sprouted were Red romaine, Winter Crop Landis Winter, Tom Thumb, Butter King, and a Winter Provencal mix.  I transplanted them a couple of weeks ago into my self-watering pots that I will cover with a portable greenhouse cover when the temperatures start getting into the 20's, later this week.  I also have volunteers of Hilton Chinese Cabbage that are also small.  

The same techniques for protecting spring crops work for your fall and winter gardens.  
Protect your new plants from a late frost
Preparing for a hard freeze

Lettuce and greens in January under a portable green house

Growth starts back up at the end of January, for indoor and outdoor plants.  The lettuce, chard, sorrel, cabbage, kale, celery, and herbs that have overwintered will start growing with vigor again after this time with clear days and warmer temperatures.

Covering plants with row covers or portable greenhouses can help your plants grow; warmth does make a difference.  Just don’t expect significant growth until we get back to at least 10 hours of sunlight.