To Cover, or Not To Cover...???

The front beds (mostly) covered with simple Agribon. The young tree in the middle is a 4-year-old Neem tree, which has changed its native habits (it's from India) to become deciduous; I'll just leave it uncovered until the coldest part of winter (since this is the first year it's in the ground) to let it fulfill its wintertime dormancy.

Yes, that is the question!

Every year at this time in North Carolina, it's hard to decide when/if to cover our highly regarded plants out in the garden. Since as a business we provide fresh-cut herbs to restaurants all year, it's in my best interest to keep everything going outside for as long as possible, so I'm not limited to the beds inside the greenhouses (though 5,000 square feet of bed space is nothing to sneeze at). However, with more than 2,000 square feet of outside beds, covering them has grown to be quite the chore!

Starting in October, around the time of the State Fair, I'm always anxiously scanning the weather reports every day, to decide when it's time to cover everything up. 39ish? 35ish? The problem is, we'll get a few nights of cold weather - we even might get to about 33 degrees - and then we'll pop right back up to the 60s and 70s, with nighttime lows in the 40s and 50s (well above the Danger Zone). For example, right now the weather forecast has lows in the 40s and 50s for the next week...

Since I have some tender tropicals like basil, lemon verbena, pineapple sage, and lemongrass outside, and I try to extend their life for as long as possible in the autumn simply by putting a layer of Agribon on them, which is basically row cover material similar to a thin cheesecloth (see the photo, above). This will often help to keep them going through the end of November. Plus, the beauty of the Agribon is that it's breathable enough to allow the rain and air in, without having to continually pull it off and put it back over the plants - saving a lot of labor!

Once it seems that we're continuously getting down into the 30s at night, which is usually some time in December (though sometimes it's later than that), I'll let those plants go to sleep and remove most of the Agribon; however, for the most tender perennials, I may leave it on top of them, in case of a really frosty winter.

An alternative to Agribon is simply using bedsheets! If you have some plants that you worry may be affected by the cold weather, and/or if you'd like to extend their life, take some cheap, low-thread count sheets (because there's a little more air allowed between the threads) and use them to cover the plants. This is useful for tender perennials in our area like bay laurel, lemongrass, lemon verbena, and scented geraniums.

Now, there are some herbs that I try to keep growing outside throughout
the winter, and there are quite a few that have an affinity for the moderately cold winters in central North Carolina! For some herbs, like chervil, parsley, mints, rosemary, cilantro, dill, and sorrel (pictured at right), I create a makeshift cold frame: We buy flexible PVC from Lowe's or Home Depot, cut it into equal lengths and insert it side to side in the beds to create hoops, place some simple greenhouse plastic over the hoops, and then clip the plastic to the hoops with row cover clips (or better yet, laundry clips) to create a small coldframe in each bed. Though the plants will grow a little slower during the coldest part of the winter, I've found this method keeps most of the cooler weather plants going... and it keeps the warmer weather plants (like rosemary) ready to go very early in the spring!

The only setback with the plastic covering is that even though it protects the plants from serious weather, it also prevents any rain/water from getting in. So, once a week or so, as miserable as it may be during the coldest part of the winter, the plastic needs to get pulled back to water the plants and then re-cover them. Also, you need to open up the ends of the beds a few times a week to make sure the plants get ventilation (otherwise, you'll end up with a moldy mess and may hurt your plants). However, if you want year-round harvesting, this is the key -- and it's a very low cost alternative to a greenhouse.

Right now, I've limited coverage to just using the Agribon, though I know that within the next few weeks, I'll be trudging out there to do the chore of putting up the hoops and plastic. For most, the Agribon/sheet method works well... and allows you to keep plants in the ground that might otherwise die or need to be brought indoors for the winter. It's always a pleasure to see the sprouts of scented geranium in the spring (note that it usually takes a little while for these plants to awaken, so if you don't see signs of them early in the season, don't lose heart) without having to replant an entire area!

So, before the cold really sets in, plan out what you might want to cover -- if you haven't already. A little bit of work now can save you a lot of work (via replanting) in the spring!