116 3rd St SE
Cedar Rapids, Iowa 52401
The Iowa Gardener: What to plant and when in Iowa
I always scratch my head when people say, “I got my garden in this weekend!” Planting in Iowa can start in March and ends in November. What garden, exactly, are they talking about?
I know, I know. They’re probably talking about their vegetable garden, with warm-season annuals like tomatoes, peppers, squash, cucumbers. Seedlings of those are typically planted outdoors at the same time in late spring.
But statements like that reflect an ill-conceived notion that there is just one time to plant in Iowa. Not so! And thank goodness, because otherwise it would be exhausting. Instead, throughout almost every month of the year, there is planting — indoors or out — that can be done, depending on the plant and its stage of development.
For spring planting, it’s crucial to keep one date in mind: your region’s last average frost date. In Cedar Rapids, that’s around May 10.
March
- Start seeds indoors of slower-growing annuals that you should start 10 to 12 weeks before the last average frost date. These include snapdragons, annual salvias and impatiens.
- 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.
- Divide any perennials that are an inch or so high and don't bloom in very early spring.
- The last week of March or first week of April, start seeds indoors of annuals that you should start 6 to 8 weeks before the last average frost date. These include marigolds, globe amaranth, sweet alyssum and flowering tobacco.
April
- 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 bare-root 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 also can 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 and based in science.
- 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.
May
Anytime in May:
- Plant container-grown trees, shrubs, and roses.
- Plant and divide perennial flowers.
- Plant grass seed and lay sod.
- Divide perennials that bloom in late summer or fall.
After the last average frost date of May 10:
- 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 also can 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 OK 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, gladiolus and tuberous begonias.
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.
July to August
- During this time, it’s 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.
- The exception is container plantings, since you are usually at this point buying large, established plants and putting them into the highly controlled environment of a container that you can keep well watered.
September
- Fall, especially right before a rainy spell is forecast, is the ideal time to plant grass seed. Water daily for about two to three weeks until well established. September is also an ideal month to lay sod, as long as you keep it well watered.
- Divide and replant 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.
- You can plant fall vegetables, like lettuces, kale, radishes and other cool-season vegetables, but it can be tricky for them to thrive if it’s very hot and dry.
October
- 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.
November
- As long as the soil doesn't freeze and you can dig down deep enough, you can continue to plant spring-blooming bulbs for the first two weeks of this month, though it is not ideal.
Veronica Lorson Fowler is co-publisher of The Iowa Gardener website at theiowagardener.com.
Basil seedlings (Dreamstime/TNS)
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