Dear Linda - I really enjoy your weekly column. My question started in the spring of last year. I tilled an area that had been crabgrass and weeds. I tilled it pretty deep and prepared it with homemade compost and top soil. As it appears now, it is once again filled with weeds and grasses of all kinds. The flowers I planted look sorely out of place. Why did this happen? How can I keep a garden and not "weed central"? Thanks, Margaret
I am not a big fan of tilling soil for four different reasons:
1) All soils have billions of dormant weed seeds in them; some of these seeds have been there for many, many years. Once the soil is disturbed (by tilling), some of those weed seeds are brought near the surface where the combination of good soil, compost, sunlight and warmth creates the perfect environment for them to grow and take over the garden bed.
2) Tilling the soil destroys the structure of the soil by breaking down the chunks of organic matter (decaying sticks, leaves, etc.) that hold water and create air spaces for roots to breathe.
3) Tilling creates a soil that has the structure of dust leading to compacted soil that has no water holding capacity.
4) Tilling kills vital soil organisms such as bacteria, fungi, microscopic insects, worms, etc. that break up the organic material which supplies the soil with nutrients.
Here's what to do next year:
1) Do not till the soil. Use a pitch fork or shovel to carefully loosen the soil around each planting hole and make sure to disturb the soil as little as possible. Amend the soil with compost in the holes only where you plant your flowers and do not fertilize the entire flower bed.
2) Add a 2-3" layer of mulch around each of your plants to help deter weeds and keep the soil moist and cool. Weeds are warm season plants that like hot weather and do not like to be shaded. Be careful not to allow the mulch to touch the plants. Each season approximately 1" of mulch will naturally decompose which is adding organic material into your garden. As the mulch layer thins, the weeds will start to pop through, so each spring restore the mulch thickness to approximately 2-3".
3) Pull the weeds when they come up throughout the season, especially before they go to seed. As time goes by, the weeding will diminish. This process could take just one season or multiple seasons.
4) Another option is to plant flowering or evergreen ground covers within your flower beds to act as a living mulch. As the groundcovers grow and spread the amount of mulch needed each year diminishes.
The bottom line is...the less you disturb the soil, the fewer weeds you will have. Thank you for a great question.
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About Linda Lillie
Linda K. Lillie is the President of Sprigs & Twigs, Inc, the premier
landscape design and maintenance, tree care, lawn care, stonework, and carpentry
service provider in southeastern Connecticut since 1997. She is a graduate of
Connecticut College in Botany, a Connecticut Master Gardener and a national
award winning landscape designer for her landscape design and landscape installation work.