April — It’s Thyme to…


Look into your crystal ball and check the 30-day weather forecast to bring your April gardening activities into focus. Number one on the list is clean or purchase a new rain gauge and post it near the garden so you can tell when it’s time to water—the garden needs about one inch of rain per week from April to September.

If you didn’t clean, sharpen, sanitize and oil your tools last fall, now is the time to get it done while the temperatures are too cool to be outside. Outside containers should also be cleaned and prepped for planting.

Earth Day, celebrated April 22, is a great time to get serious about gardening. Re-mulch walkways to provide a “clean” garden path and avoid walking in mud. Add compost to the garden and till it in when the soil is dry enough to avoid compacting.

Trim tattered foliage to encourage new growth. Divide your perennials including ornamental grasses, aster, mums, hosta, bee balm, sedum, yarrow, salvia and coneflowers.

Weekly April gardening tips

Week 1 — Summer flowering shrubs can be trimmed back to the ground (spirea and Annabelle hydrangea) since they bloom on new wood and will quickly grow back and bloom in mid-summer.

Week 2 — Rake the lawn to remove dead grass, sticks and debris. It’s also time to fertilize and reseed the lawn. Spring aeration is very beneficial. Going over high-traffic areas multiple times to reduce soil compaction is recommended. When you can work the soil easily, plant cool-season vegetables such as peas, radishes, spinach, and lettuce. The average last frost date for our area is somewhere between April 17 and May 4.

Week 3 — For seeds started last month, transplant seedlings into 4-inch pots when they are about 1 inch tall. Keep plants indoors in a arm, bright location until “hardening” off and transplanting outdoors in mid to late May.

Week 4 — Reseed bare spots in the lawn with a mix of Kentucky bluegrass, perennial ryegrass and fescue. Be sure to remove dead grass first so the new seed is in direct contact with bare soil.

Week 5 — Fertilize apple trees, grape vines and strawberries. When the forsythia blooms, it’s time to tend to your roses. Pull the mulch away from the base of the plant, remove dead stalks and fertilize.

Spring is a good time to stake perennial plants before they need support.

If you’ve always wanted an asparagus patch, when the soil is dry enough to work, dig a trench, 6 to 10 inches deep (the depth will depend on the type of soil you have). Work in organic fertilizer before planting the crowns, spacing them 12 to 18 inches apart with buds pointing up, and cover with soil. If you have enough space to plant multiple rows, space the rows 4 to 5 feet apart. The site should be well-drained and receive 6 hours of sun. Be patient—because you should wait 1 to 2 years before harvesting your first asparagus crop.

The rhubarb should be popping out of the ground now. Harvest when the stalks are 10 to 15 inches tall. Grasp the stalk at the base and pull it up and slightly to one side. Do not remove more than half of the fully developed stalks from any plant at any one time.

Late in the month, acclimate transplants started indoors or purchased before planting outdoors. Place plants in a protected shady area. After a day or two, gradually expose the plants to longer periods outdoors and in direct sun. After 7 to 10 days of “hardening,” the plants should be ready to be planted in the garden.

This dandy downloadable spreadsheet from BetterHensandGardens.com is helpful to create a personal planting calendar. https://www.betterhensandgardens.com/wp-content/uploads/2023/01/2023-Vegetable-Planting-Schedule.xlsx

While you are planning and planting, please consider Plant A Row and grow to give to area food pantries. JCMG tracks donations to area food pantries. Johnson County Master Gardeners’ service hours and donations consistently rank among the high-population counties of Polk, Linn, Blackhawk and Scott.

Remember your houseplants—it’s time to fertilize. If you are interested in testing your soil to determine its fertilizer needs, samples can be submitted to one of the laboratories listed at https://hortnews.extension.iastate.edu/soil-testing-resources-home-gardeners