Frost Free Date -- What to Plant

May 14, 2010 We must emphasize that the frost free date, May 15th, is an average date for the last freezing conditions of the year. It is also a "symbolic" date for warmer soil temperatures that the warm season annuals require to grow without getting diseases. Plant only frost tolerant plants before this date, and be prepared to protect tender plants until May 30th because of the "average" factor of the May 15th date.

FROST FREE DATE - May 15 in Chicago area

COOL-SEASON ANNUALS, frost-tolerant annuals, safe to plant in the garden prior to the frost free date; pansies, violas, snapdragons, petunias, sweet alysssum, dianthus stock and lobelia

Cool-season annuals

* Plants that are frost tolerant (down to mid 20's F), that can be planted now to awaken our gardens with color

* Possible plants: Pansies and violas, Primroses, Bellis (English daisies), Sweet alyssum, Stock, Snapdragons, Forget-me-nots

WARM-SEASON ANNUALS, better to wait until danger of frost has passed, (after frost free date): geraniums, begonias, impatiens, zinnias, periwinkle, nicotiana, cleome, torenia, lantana, verbena

Warm-season annuals

* Plants that need warm soil temperatures to develop and grow, 65-70 degrees F

* Plants: Geraniums, Impatiens, Begonias, Torenias, Cupheas, Zinnias, Vincas, Nicotianas, Celosias, Portulacas, etc.

* If you have already planted these plants because the weather has tempted you, be prepared to protect them if freezing temperatures are predicted; covering with large sheets to hold ground temperatures around the plants usually is satisfactory.

VEGETABLES, there are also cool-season and warm-season vegetables

A.) Cool season; lettuce, peas, onions, cabbage, kale, spinach, radish

B.) Warm season; tomatoes, peppers, cucumber, corn. zucchini

C.) Plant most transplants at the same level at which they were growing,the one exception is tomatoes - to encourage additional rooting, strip the leaves off the stem and plant 4-6 inches deeper, laying the stem on its side, and covering it with soil

HERBS; most herbs require warm soil temperatures and full sun to perform best, especially basil (which does not like temperatures to go below 40 degrees F)

PERENNIALS, it is completely safe to plant any perennials now, especially natives (so use your energy on the perennial beds until the temperatures warm up)


· It is an average date, so sometimes there can be cold temperatures even after 5-15 – be prepared to protect any plant that is tender

· It is not just the air temperature that can make a plant happy or unhappy – the soil temperature is often even more important – THIS YEAR WE ARE LUCKY – THE SOIL HAS WARMED UP EARLY – yesterday it was 66 degrees F.

· As of tomorrow it is safe to plant the plants that are "offended" by colder temperatures.

PLANTS FEATURED FOR THE "Frost Free Date" 5-15-10:

Classic sub-tropical plants that have so much color:

· New Guinea Impatiens – "Infinity Blushing Crimson" $4.99 / 4" pot SHADE or SUN

· Fuchsia Standard (tree form) - $39.99 MORNING SUN, AFTERNOON SHADE

· Geranium "Patriot Bright Violet" $24.99 / 7" pot FULL SUN

· Mandevilla "Red Riding Hood" trained vine $22.99 SUN

Heat loving annuals:

· Angelonia (white) – loves hot and dry conditions, but looks so delicate $4.99 / 4" pot SUN

· Cleome (purple) – Spider Flower – gets 3-4' tall lasts all summer $4.99 / 4" pot SUN

· Annual Flowering Vinca (cherry red)- looks like regular impatiens but loves hot, dry SUN

· Zinnias "Magellan Mix" – not too tall, not too short, great colors all summer SUN

Trailing plants:

· Bacopa – beautiful white flowering trailer that can live in SUN or SHADE

· Baby Blue Eyes – beautiful blue flowers on cascading stems SUN

Vegetables and Herbs (all of these would have grown poorly if planted earlier):

· Basil – completely offended by temperatures below 40 degrees F – note damaged leaves

· Tomatoes – "Tomatoberry", shaped like a strawberry, with a pointed end and very sweet

· Peppers – "Super Banana", yellow and sweet; "Red Beauty", sweet red bell type; "Salsarific", spicy with some heat; and "Whopper", a large bell type

· Cucumber "Burpless" – best to avoid cucumber beetle pest

· Squash "Vegetable Spagetti"

· Corn – Sweet and Popcorn

· Eggplant "Whopper"

Chalet Nursery
3132 Lake Ave.

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