Roots and Shoots: Weeds, Veggies and Transplants


Another use for thicker cardboard: a base layer for mulch between raised beds. (Photo by P. Doan)

This week I’ll answer some questions from Current readers.

Q: What are the merits for weed suppression of newspaper versus cardboard?

It depends on the circumstance, the purpose and type of cardboard. For those of us who aren’t using herbicides, both options are useful. One summer I had a vegetable plot in a community garden and the weeds were intense. Surrounded by dozens of other plots and a history of various gardening approaches, the seedbed was robust and communal. A layer of newspaper around the plants and between rows in such an instance would be a huge help in maintenance. The newspaper will break down by the end of the season and not smother the soil beneath. 

Cardboard is just thicker and it can be coated, making it water-resistant, which you don’t want in the garden. I use it carefully, and more commonly when I’m creating a new bed, to smother whatever is growing so that I can plant without tilling. I prefer rolls of single layer cardboard because it breaks down faster when I’m creating a landscape without tilling the soil. 

This technique allows me to plant on top of the soil instead of destroying all the microbes by digging or tilling to manage the plants. The cardboard will suppress the weeds for long enough to give the plants I want to take over a chance. 

Notably, many of the weeds gardeners deal with are not what I call “regular” weeds, e.g., the quackgrass, purslane and plantain I grew up pulling. Instead, it’s Japanese stiltgrass, mugwort, garlic mustard, Oriental bittersweet, Japanese knotweed and barberry — invasive species that are much more difficult to control. 

Q: Can a 15-year-old peony plant be safely moved and replanted? 

Yes. Choose a site that has full sun and dig up the peony about a foot out from the crown of the plant. Try to keep as much of the root ball as possible because that is what will give the plant its best chance to thrive after being transplanted. If it’s late August or September, you could cut the plant down to about 6 inches since it’s going into dormancy anyway. 

If you can find the nubs that will be next year’s growth, those are your guiding line for how deep to plant into the hole. If you bury it too deep, it won’t find its way back. Water it in well after planting but don’t worry about regular watering in the fall. 

Q: Are three cherry tomato plants and three baby watermelon plants in a planter too much? It is 3 square feet and the watermelons are showing melons already. 

That is a tight fit! As a general rule, cherry tomatoes need 12 to 24 inches per plant and watermelon up to 6 feet. Even in fertile soil, all of those plants won’t get enough nutrients. If possible, move the plants to locations with more room and you’ll enjoy more tomatoes and watermelons. 

Q: My zucchini is flowering but my squash shrivels. What is wrong? 

This has to do with pollination. Squash blossoms used for cooking are usually made from the first flowers, which are all male. Female flowers bloom next and then the plant fruits. My advice is to wait. 

Q: Does Queen Anne’s lace grow back from the root system or does it reseed? I like it in my garden and want it to return in the same spot. 

Daucus carota is a biennial plant that has a taproot. In the first season, it will have foliage but not blooms. If your plant is in bloom this season, this is the second year of its life cycle and it will be finished. You can collect seeds once it turns brown and curls up into a nest shape.

Have your own questions? Email [email protected].

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