Here’s what to do if your basil is turning yellow

Ask the Expert Gardening
Microgreens of basil are pictured in Saint-Jean-en-Val, France, on May 22, 2018.
Microgreens of basil are pictured in Saint-Jean-en-Val, France, on May 22, 2018. Getty Images

What to do this week: If your container gardens are faltering, replace the bloomed-out flowers with fall mums or kale. Move houseplants back indoors after cutting them back and spraying them with insecticidal soap. The heaviest deer browsing occurs in October, so start spraying evergreens with repellent now so they don’t get in the habit of visiting. Overseed now so grass will fill in the spaces left when crabgrass and other annual lawn weeds die off. Keep seeded soil damp. Use a starter fertilizer for grass seedlings after they sprout. If your lawn is in the shade, overseed with a shade mix or replace it with a shady ground cover. Try a “sports turf’’ seed blend of bluegrass and rye if your lawn is high traffic. Fertilize established lawns with a “slow release’’ organic “time release’’ fertilizer to reduce watershed-polluting nitrogen runoff.


Q. I think the soil in my 12-year-old raised bed needs to be revitalized, and I’m not sure when or how to do it. I don’t have a heavy hand when it comes to fertilizer, so maybe I just need to add some regularly. Do I just need to add organic material like compost, or is there something else I should do? Do I do something after I clean up the garden this fall, or should I wait until spring?

K.W., Yarmouth Port

A. The easiest way to revitalize your raised bed is to buy a few bags of well-rotted cow manure and spread it on top of the garden after the end of the season. The trend in garden improvement is to layer soil amendments rather than rototill them in. This lets the worms integrate the material through the offseason so you don’t disrupt the existing soil organisms. Since you are on the Cape, you could also experiment with adding seaweed, which is full of accessible micronutrients seldom found in commercial fertilizers. Some people also add it as a mulch between plants during the growing season because the salt discourages slugs while feeding the soil. It also contains no viable weed seeds. Gather relatively dry, broken-down seaweed with small leaves from several locations. Worried about salt? You can hose it off in the driveway first, but most people don’t bother.


Q. Why are the leaves turning half yellow on my basil, and is there anything I can do?


A. There are three reasons why basil yellows: too much water, too little sun, and/or not enough nutrients. Stop watering, move the pot to a sunnier location, and feed it with a balanced 10-10-10 fertilizer.