Weeds in winter are not uncommon

On a nice winter day, I took a stroll and found my garden covered with weeds. This garden was bare soil last fall when I put it to bed. Not a weed in sight. Now it's a blanket of bright green flourishing weeds! How can that be?

Those are winter annual weeds. Their seeds sprout in fall or early winter. They're inconspicuous at first, and in a bitter winter they don't really do much until spring. But with all our warm days this winter, they've been growing like gangbusters. Chickweed is a common one. You can pull them out. Or, since they don't have extensive root systems, most can be cut to the ground and will not regrow. Another option is to mulch heavily to smother them. Next fall, instead of leaving soil bare, cover it with mulch to prevent seeds from getting light which they need to germinate or sprout.

Is winter a good time to repot my houseplants?

Most prefer repotting in spring, as they begin active growth. However, not all houseplants should be repotted yearly. Some like their roots to be cramped; others like a pot small in proportion to the plant's size. For these, wait until roots show on the soil surface or are crawling out of the pot. Since overwatering, not underwatering, is the No. 1 killer of houseplants, repotting into what seems like a nice big pot increases the chance of plant drowning. A small plant in a big pot is unable to use up water fast enough, which results in soggy soil and rotting. Most plants should be repotted into a pot just one size larger. Check what's best for each species of plant or call us.

University of Maryland Extension's Home and Garden Information Center offers free gardening and pest information. Call 800-342-2507 or send a question to the website at hgic.umd.edu.

Plant of the Week

Lichen ssp.

Technically lichen is not a plant. It is algae cells enclosed in fungal cells, working together in a symbiotic relationship. Lichen (the word is singular and plural) draws water and nutrients out of air. That's how it can live on inhospitable surfaces such as a rock or fence or tree trunk. Although it attaches, it has no roots so surfaces are not harmed. A common tree lichen in Maryland is greenish gray and crusty, but combinations of different algae and fungi have evolved into many lichen colors and forms. Their main enemy is air pollution, because they depend on air for sustenance. Lichen on a tree is not cause for alarm. A tree covered in lichen, however, may signal other problems. — Ellen Nibali

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