Garden dreams Every 60-degree day in March gets gardeners and would-be gardeners excited about spring planting. That's fine for some types of plants, but for others, early planting could create extra work or cause the loss of your investment before the season even gets started.
Understanding cool- and warm-season crops, annuals and perennials, and dates of last frost can help get the garden off to a better start and increase the likelihood of success with the garden.
Peas and carrots - they really do go together! Cool- vs warm-season crops
Some plants grow best in spring and fall when temperatures are mild. Others grow best in the heat of summer.
In the Kansas City metro area (Kansas and Missouri), mid-March is the beginning of planting season. Select cool-season crops such as peas and potatoes for earliest plantings. Plant cool-season crops from mid-March to the end of April unless the crop is also heat tolerant. For example, late plantings of broccoli and cauliflower are unlikely to produce heads, and late plantings of radishes and spinach will sprout and then bolt (produce flowers/seeds instead of leaves and roots). But, swiss chard will grow through the cold and heat.
Plant warm-season crops from mid-April to the first of June, depending on the crop and your willingness to take risks. If you plant tomatoes earlier than that, they will almost undoubtedly freeze! Warm-season crops that cannot tolerate cold temperatures and are also affected by soil temperature. See the sections below for more information on risk factors.
Examples of cool-season crops:
arugula, beets, broccoli, cabbage, carrots, cauliflower, lettuce, peas, potatoes, radishes, spinach, swiss chard, turnips
Examples of warm-season crops:
basil, beans, gourds, melons, okra, peppers, pumpkins, sweet corn, sweet potatoes, squash, tomatoes
Some plants grow best in spring and fall when temperatures are mild. Others grow best in the heat of summer.
In the Kansas City metro area (Kansas and Missouri), mid-March is the beginning of planting season. Select cool-season crops such as peas and potatoes for earliest plantings. Plant cool-season crops from mid-March to the end of April unless the crop is also heat tolerant. For example, late plantings of broccoli and cauliflower are unlikely to produce heads, and late plantings of radishes and spinach will sprout and then bolt (produce flowers/seeds instead of leaves and roots). But, swiss chard will grow through the cold and heat.
Plant warm-season crops from mid-April to the first of June, depending on the crop and your willingness to take risks. If you plant tomatoes earlier than that, they will almost undoubtedly freeze! Warm-season crops that cannot tolerate cold temperatures and are also affected by soil temperature. See the sections below for more information on risk factors.
Examples of cool-season crops:
arugula, beets, broccoli, cabbage, carrots, cauliflower, lettuce, peas, potatoes, radishes, spinach, swiss chard, turnips
Examples of warm-season crops:
basil, beans, gourds, melons, okra, peppers, pumpkins, sweet corn, sweet potatoes, squash, tomatoes
Annuals vs. perennials
Annuals are plants that live for one growing season and produce flowers and seeds within that cycle. Examples of annuals are most vegetable crops and many common weeds such as henbit and crabgrass.
Perennials are plants that survive many years despite flowering. Examples of perennials are asparagus, rhubarb, and many common flowers such as daisies, daylilies, phlox, and others.
Why does this matter? Use it to bend the rules with spring planting. Heat-loving perennials can be planted in early spring because they are cold hardy. Herbs are great examples of this - chives, oregano, sage, thyme, and others are perennial in the Midwest. Plant them early as early as preferred if they can be obtained.
Annuals are plants that live for one growing season and produce flowers and seeds within that cycle. Examples of annuals are most vegetable crops and many common weeds such as henbit and crabgrass.
Perennials are plants that survive many years despite flowering. Examples of perennials are asparagus, rhubarb, and many common flowers such as daisies, daylilies, phlox, and others.
Why does this matter? Use it to bend the rules with spring planting. Heat-loving perennials can be planted in early spring because they are cold hardy. Herbs are great examples of this - chives, oregano, sage, thyme, and others are perennial in the Midwest. Plant them early as early as preferred if they can be obtained.
Row cover protecting an early planting of squash Average date of last frost vs frost-free date
The average date of last frost is the date when there is a 50-50 chance of frost occurring after that date based on climate history for a particular area.
The frost-free date is when there is a 5 percent or less chance of frost occurring after that date.
In the Kansas City Metro area, the average date of last frost is April 11-18. The frost-free date is May 4.
Here's the Kansas map for reference:
http://climate.k-state.edu/maps/special/freeze/Average+Spring+Freeze.png
To be safe, wait to plant warm-season crops until after the average date of last frost.
To take the safer route, wait to plant them until after the frost-free date.
To take the safest route, wait until after the frost-free date AND check soil temperatures* prior to planting.
If warm-season crops are planted and frost/freezing temperatures are predicted, protect plants by covering them with buckets, sheets, blankets, row cover, or other similar items.
*To check soil temperature, use a specialty thermometer made for it, available at many garden centers. Or, use any thermometer with a probe that can be stuck into the soil and displays temperatures down to 40 degrees F.
The average date of last frost is the date when there is a 50-50 chance of frost occurring after that date based on climate history for a particular area.
The frost-free date is when there is a 5 percent or less chance of frost occurring after that date.
In the Kansas City Metro area, the average date of last frost is April 11-18. The frost-free date is May 4.
Here's the Kansas map for reference:
http://climate.k-state.edu/maps/special/freeze/Average+Spring+Freeze.png
To be safe, wait to plant warm-season crops until after the average date of last frost.
To take the safer route, wait to plant them until after the frost-free date.
To take the safest route, wait until after the frost-free date AND check soil temperatures* prior to planting.
If warm-season crops are planted and frost/freezing temperatures are predicted, protect plants by covering them with buckets, sheets, blankets, row cover, or other similar items.
*To check soil temperature, use a specialty thermometer made for it, available at many garden centers. Or, use any thermometer with a probe that can be stuck into the soil and displays temperatures down to 40 degrees F.
Until next time, Happy Gardening!
-The Garden Girl
-The Garden Girl