With the hottest days of August behind us, this is a great time to plan for cooler times ahead. Particularly at the juncture of two seasons, your greenhouse provides a growing environment sheltered from increasingly unpredicatable weather. Chilly nights? Just close the vents and let the thermostat bring on a little heat. Indian Summer? Re-open the vents and doors.
While outdoor crops are likely to be affected by these seasonal fluctuations—weathering increasingly cool fall temperatures, and eventually, frost—with a little well-timed intervention, your greenhouse plants can continue to flourish. Of course, even inside the greenhouse, summer temperatures won’t necessarily remain for long. And don’t forget to take into account the shortening day length at this time of year. Some crops are better candidates to grow under these conditions than others.
The vegetables best suited to fall and winter greenhouses are those which thrive in relatively cool temperatures– so that you don’t have to crank the heat way up to keep them happy– and that also don’t require maximum light levels. In other words, it’s the perfect time of year for growing greens and herbs.
Grow your own salad mix, by planting any of the widely available seed packets. Other greens, like spinach and arugula, will also appreciate cooler growing conditions. Herbs like chervil, chives, cilantro, dill, parsley, rosemary, savory, tarragon and thyme are all handy in the kitchen through the winter.
If you already have large specimens of perennial herbs in containers, just bring them indoors. This is a good time to give those large plants a good trim; they will take up less room inside, and be easier to care for too. Just make sure to check them well for insect populations; after making a thorough visual inspection, wash with insecticidal soap as a precaution. If you do find evidence of an infestation, spray at least twice. Taking the time to do so before moving them inside will save you considerable heartache later. Once plants are in a small, closed system, it becomes much more challenging to eradicate problems.
By planning ahead, you can harvest salads and green vegetables through much of the winter. Remember to thin seedlings and leave room around potted specimens. Crowding can reduce light and encourage disease and insect pests. Avoid overwatering too. Harvest often, and enjoy!