A Gardener’s Diary: Tubers may be left in the ground after first frost

Jocelyne Sewell shares a few tips for extending the harvest season of Jerusalem artichokes

The Jerusalem artichokes I planted in the spring must have loved the rain of June and the summer heat. Some of them grew more than eight feet tall. Their nice small yellow flowers are a bright sight in the garden at this time when most of the blooms are now vanishing.

We have been so lucky with this beautiful weather. Although the days are warm, the nights are cool and the growth is slowing down, and one of these nights we will have some frost. Since freezing doesn’t injure the tubers, they may be left in the ground indefinitely after fall frosts, a fresh supply being dug as needed throughout the off-season. In fact, leaving them in the ground is a practical storage method for this vegetable whose tender skin doesn’t make it a particularly good indoor keeper.

Those that are brought in should be kept quite moist and if necessary given a daily soaking in water prior to use. It is best to dig up only the amount you plan to use immediately. The tops can be cut and fed to the compost. With the arrival of spring, tubers left in the ground should be dug either for eating or replanting. If an increased supply is wanted, some may simply be left to multiply.

I had some very small dahlia tubers which I had planted in four-inch pots in May. I finally transplanted them in the ground after I dug up the garlic. They receive only the morning sun and they still managed to bloom. They bloom in autumn and come in a vast range of colours and forms. They make excellent cut flowers. Somebody told me that he dips his flowers in warm water to bring in the house and it gets rid of earwigs, as they love dahlias. After the tops are killed by the first heavy frost, the clumps should be dug. Cut the tops off three or four inches above the ground level. Let the tubers ripen in the ground for about one week. When you are ready to lift them, loosen the soil all around and under the clumps so that it may be lifted without breaking off any of the tubers. A tuber with a broken neck is useless for planting again and should be discarded.

Let the clump dry in the sun and air for a few days. Place under cover for continued drying. There is no need to remove any adhering soil as this will help to keep the roots plump. In one of my books, it says to spread a two-inch layer of dry sand in the bottom of a box, place the roots on top and then fill with sand until at least three inches cover the clumps. Store the boxes in a cool, frost-proof cellar. Other people just store them in peat moss. I store mine in open plastic bags in which I have put some peat moss, then lay the tubers in the bags and cover them with more peat moss. They are stored in large containers in the basement. I have to watch for early growth, as the basement is not that cold. The ones I grow in pots, I only cut the stems and store them in their pots. So far so good.

I was given a fig cutting last year. I overwintered it in a one-gallon pot and repotted it in June. Last week I had a taste of the first ripe fig. I hope the other three ripen soon. They are delicious.

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Jocelyne Sewell is The Morning Star’s gardening columnist, appearing every other Wednesday.