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Wednesday, February 21, 2024

Dear Garden Problem Lady

How do you keep tuberous begonias over the winter? Are dahlias the same?

Neither shade-loving tuberous begonias, nor full-sun loving dahlia tubers can survive DC winters. By December cut all leaves and stems back to the shallow horizontal tubers (roots) of your plants.

Lift the tubers, dry them with a soft cloth and place them atop a single layer of peat moss, vermiculite, or sawdust in a low cardboard box. Then cover the tubers with additional peat, vermiculite, or sawdust. Store in a temperature of 40 to 50 degrees Fahrenheit. Do not allow the tubers to freeze. Replant in spring after all danger of frost is gone.

I know autumn is the time to plant spring-flowering bulbs, but what about alliums – they bloom kind of late. Are they more like lily bulbs, which one can plant in the spring?

Plant allium bulbs in the fall. As with all flower bulbs, plant alliums to the same depth as the bulb itself – up to six inches deep. They need full sun. Because they are tall plants put allium bulbs a good 12 to 14 inches apart. Then water moderately. Soil must drain well – avoid places where rainwater pools. Next year, after bloom ends in mid-summer, leave the leave on until they dry
up completely.

Exactly how does water flow upward in plant roots and stems (against gravity)?

Your question demands an understanding of botany at a cellular level, which I will try to simplify radically. The same thing happens physiologically inside the bodies of animals. Know simply that inside every plant there are two very narrow tubes (ducts) inside stems and trunks. These two narrow tubes distribute water and nutrients (minerals, carbohydrates) both upwards and downwards. Also know that water molecules are charged – they have an electrical attraction to each other and cohere. The two tubes are called Xylem and Phloem.

Inside these narrow tubes (as narrow as the veins in a human body), cohesive water molecules create a force stronger than gravity to push all the way from plant roots to tree-tops. Xylem lets water and nutrients move in only one direction, up, from roots. Phloem lets water and nutrients travel both up and down the plant, from top leaves down.

These chemical reactions depend also on sunlight (Photosynthesis) and the reactiveness of water (Hydrolysis), both of which chemically react with nutrients and minerals inside the narrow tubes, to create – synthesize — food in the forms that plants need.

Capitol Hill Garden Club meetings are free and open to all. At the NE Library on Tuesday November 14 at 6:30 pm, Hillwood Museum Horticulturist Drew Asbury will illustrate “Succession Planting” – how and what to plant for all four seasons.

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