April onion and companion‑plant tips
Garden guides say April is a key month to weed, feed and water onion beds—and that there’s still time to plant for large bulbs if you move quickly (homesandgardens.com). Companion‑plant advice is circulating too: sweet alyssum is being recommended alongside rosemary to boost pest resistance and pollinator appeal in small gardens (housedigest.com).
April is a make-or-break month for onion beds: gardeners still have time to plant for full bulbs, but late planting can leave onions small. (extension.illinois.edu) Onions are cool-season plants with shallow roots, and Illinois Extension says they compete poorly with weeds and grasses. Minnesota Extension says full sun is essential, and cool, overcast weather can delay bulb formation. (extension.illinois.edu) (extension.umn.edu) Bulb size depends on day length as much as watering and feeding. Nebraska Extension says short-day onions start bulbing at about 10 to 12 hours of daylight, intermediate types at about 12 to 14 hours, and long-day onions at about 14 hours or more. (lancaster.unl.edu) That is why planting advice changes by region. North Carolina State Extension says intermediate-day onions bulb at roughly 12 to 14 hours of daylight, while long-day onions need 14 to 16 hours, and Illinois Extension says southern varieties usually do not adapt well in the North. (content.ces.ncsu.edu) (extension.illinois.edu) The April to-do list is mostly basic maintenance. Garden guides are urging growers to keep onion rows weed-free, water steadily, and feed plants while leaves are still building the energy that later swells the bulb. (homesandgardens.com) (extension.illinois.edu) A second strand of spring advice focuses on companion planting around herbs. House Digest highlighted sweet alyssum as a rosemary partner because both prefer sun and well-drained soil, and sweet alyssum can tolerate some shade from larger rosemary branches. (housedigest.com) Sweet alyssum is a low, spreading annual that typically grows about 3 to 9 inches tall, according to Wisconsin Horticulture. North Carolina Extension and Clemson Extension both say it attracts beneficial insects, including syrphid flies and parasitoid wasps that help suppress pests. (hort.extension.wisc.edu) (plants.ces.ncsu.edu) (hgic.clemson.edu) The match is not perfect everywhere. Wisconsin and Illinois extension guides say sweet alyssum flowers best in full sun to partial shade and well-drained soil, but blooming can fade in hot summer weather unless plants are cut back. (hort.extension.wisc.edu) (extension.illinois.edu) For gardeners in mid-April, the practical rule is simple: pick the right onion type for your latitude, keep beds clean and moist, and use companions like sweet alyssum where the site suits both plants. (extension.umn.edu) (agsci.oregonstate.edu)) (hort.extension.wisc.edu)
