Planting Calendar for Iowa

Start seeds indoors only of those very slowly growing plants, such as parsley, thyme, or certain perennials. If you start other seeds now, they’ll get leggy and weak before you can plant them outdoors. (Many can’t be planted outside until May.)

Start seeds indoors of leeks, onions, broccolli, cabbage, cauliflower, and perennial flowers and herbs now. Avoid planting seeds of most other plants until March and April.

In the first half of the month:

Once you can easily work the soil outside, plant directly in the ground seeds of fast-germinating cool-season vegetables, such as radishes, spinaches, and lettuces.

Start seeds indoors of slower-growing annuals that you should start 10-12 weeks before the last average frost date. These include snapdragons, annual salvias, and impatiens.

In the second half of the month:

Divide any perennials that are an inch or so high and don’t bloom in very early spring.
In southern Iowa, plant bareroot trees, shrubs, and roses.
The last week of March or first week of April, start seeds indoors of annuals that you should start 6-8 weeks before the last average frost date. These include marigolds, globe amaranth, sweet alyssum, and flowering tobacco.

The first week or so of the month, plant directly in the ground easy, fast-growing annuals that like cool weather, including bachelor’s buttons, larkspur, and California poppy.
Plant bareroot trees, shrubs, and roses.
Plant container-grown trees, shrubs, and roses.
Plant seedlings of cool-season flowers, such as pansies and snapdragons.
Plant seedlings of cool-season vegetables, such as broccoli, cauliflower, and cabbage.
Plant seeds of cool-season vegetables, such as lettuces, spinach, greens, radishes, and more.
Plant those herbs that like cool weather, including parsley and cilantro. You can also plant seedlings of perennial herbs, such as oregano, sage, and thyme, outdoors now.
Plant peas from seed when lilac leaves are as big as a mouse’s ear, according to folk wisdom.
Plant potatoes on Good Friday, also according to folk wisdom.
Plant grass seed and lay sod.
Plant seedlings of perennial flowers.
Plant starts of perennial edibles, such as strawberries, rhubarb, raspberries, and asparagus.
Divide perennials flowers that bloom in late spring, summer, or fall.
The last week or so of the month, start seeds indoors of fast-growing annual flowers, if you want to give them a head start. (Otherwise, start them outdoors later directly in the ground.) These include sunflowers, cosmos, nasturtiums, zinnias, and hollyhocks.

Any time in May:

After last average frost date
(May 10 in southern Iowa, May 15 in northern Iowa)

Plant seedlings of warm-season annual flowers, such as marigolds, impatiens, petunias.
Plant seeds directly in the ground of easy, fast-growing annuals that like warmer weather, such as sunflowers, cosmos, nasturtiums, zinnias, and hollyhocks.
Plant seedlings of warm-season annual vegetables, such as tomatoes, peppers, and eggplant.
You can also plant seedlings of squashes, cucumbers, and melons now. (Plant seeds of these a little later, if you choose to go that route. They need warm soil to germinate but are okay to plant as seedlings now since they need less warmth once already started.)
Plant seedlings of warm-season herbs, such as basil.
Plant summer-flowering tropical-type bulbs and tubers, such as cannas, elephant’s ear, gladilous, and tuberous begonias.
In southern Iowa, the last week of May, plant seeds that need warmer soil, including corn, squash, cucumbers, green beans, and melons.

In northern Iowa, the first week of June, plant seeds that need warmer soil, including corn, squash, cucumbers, green beans, and melons.
If necessary, plant grass seed.
Divide spring-blooming perennials, but avoid doing so during hot, dry spells.
Lay sod.

Usually too hot and dry to plant. If absolutely necessary, plant or divide on cooler, overcast days and water well for the next two weeks

Plant grass seed, but be sure to water daily until established. In northern Iowa, the first half of the month is an ideal time to plant grass seed and lay sod. In southern Iowa, the second half of the month is an ideal time.
In the second half of the month, plant spring-blooming bulbs, such as tulips and daffodils. You can also plant Asiatic and other true lilies now.
Divide spring-blooming perennials.
If necessary, plant perennials, trees, shrubs, and container-grown roses now. However, they may have to struggle through hot weather this month and also not have enough time to get established before very cold weather hits.

Plant grass seed and lay sod the first half of the month.
Plant spring-blooming bulbs this month, the ideal time.
If necessary, plant perennials. They may not have enough time to get established, though, before very cold weather hits.

As long as the soil doesn’t freeze and you can dig down deep enough, you can continue to plant spring-blooming bulbs though it’s not ideal.