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Why We Grow Outdoors

Proven Profits


Why We Grow Outdoors

Growing crops outside in spring and summer offers advantages we just can't overlook. They can mean extra profitability for you, too!

By Brian Bourdon, Offsite/Product Line Manager

While the practice of growing crops outdoors isn't new, growers can be understandably hesitant about trying it for the first time with annual crops that can freeze. Our team at Four Star has learned how to make best use of the advantages of this practice for producing hardy, healthy, retail ready plants.

Outdoor growing
Outdoor growing allows growers to move established crops
outdoors and free up indoor space for planting more turns.

Outdoor Growing in Brief

• Outdoor growing produces compact, healthier plants
• Plants are acclimated to the weather and ready for retail
• Fewer, if any, growth regulators are needed
• Fewer, if any, fungicides are needed
• Fewer insect issues, especially early season
• Great way to hold crops
• Shifting crops outdoors opens up additional growing space indoors for extra turns and income.
• Saves you money! Outdoor growing eliminates the heating and electric bills for these crops.

We've been growing a large percentage of our crops outdoors for over 10 years now, and are happy to share our tips to be successful with any growers who are interested. Currently, we grow about 25% of our crops for late May sales outside, and as much as 80% of our summer crops. We start moving some of our hardy annual crops outdoors 4-5 weeks before our frost free date — as soon as nighttime temperatures average in the high 30s — and we continue to grow as much as we can outside through the summer and into fall.

Outdoor Growing Advantages

Many growers perceive outdoor growing as full of risks, but we see far more benefits to it. For one thing, Mother Nature does a great job of helping plants grow, and when we get the plants outside and exposed to the wind, the unfiltered sunlight, and cool night air, they grow into better plants — stronger stems, lots of flowers, and more hardy. You just can't duplicate this inside!

Outdoor growing also helps increase our turns and use our greenhouse space more effectively by allowing us to plant more inside as we move established crops outside. We use all kinds of spaces — protected or unprotected courtyards, outdoor mum fields, and cold frames. You could even use an empty parking lot!

sprinklersSprinklers attached to the greenhouse keep outdoor crops protected in case of heavy frost.

Many growers in early spring have mum fields sitting empty and greenhouses full. Considering this method can truly help expand your profit potential. Not only is it cheap growing space with little to no structure, heat, or electricity costs, but the plants also typically require no growth regulators, and few if any pesticides or fungicides.

Four Star's Top Outdoor Growing Tips

1. Know your crops. Identify varieties that will grow best outside in cold temperatures. Based on temperature, we have identified three levels of crops we move outside as the night temperatures gradually climb (see sidebar).

2. Start slowly! Outdoor growing is an investment in plants, pots, trays, as well as equipment for irrigation and frost protection. I would recommend to tentative growers to start with just a small amount of product and expand the program from there as you become more comfortable.

3. Get the timing right! Make sure your crop is well rooted, typically at least two to three weeks old before moving it outside, and before the move, make sure your weather forecast is for calm, dry weather with no severe frost for the first few days. After that, your crop will harden off to withstand colder temperatures.

4. Be prepared before bad weather hits. Make sure you have appropriate frost protection systems like frost cloth, sprinklers, etc. With no protection we incurred some freeze damage when we first started. Using sprinklers during frost events (as citrus growers do) insulates plants and helps them survive weather extremes.

Cold weather
While outdoor growing is subject to weather extremes, the use of protective sprinkling and selection of hardy crops can minimize damage. In the large photo, this Argyranthemum crop is covered with ice at 7 a.m. In the inset, a plant from that crop at 10:30 a.m. shows how quickly they thaw and recover.

5. Maintain proper fertility levels. For all baskets and upright containers going outside, we top-dress with a slow release fertilizer to help during periods of extended rain. In addition, after a heavy rain, we follow up right away with a 600ppm N fertilizer application to replace what has been leached out. You don't want to wait for them to dry out first.

6. Realize there are still some risks involved. If you have a sales date you must hit for a customer, it is best not to grow those crops outdoors. The weather can make it difficult to grow to a precise schedule. But for the crops you speculate on, growing outdoors will give you some of the best product you have ever grown.

Plants That Love Outdoors

Based on our experience, we've developed three groups of frost tolerant annuals that work for us in southern Michigan. Contact us if you have questions about specific varieties in your location.

Group 1
Can take frost down to 25 degrees
• Butterfly, Vanilla Butterfly® Argyranthemums
• Symphony series Osteospermum
• Supertunia®, Surfinia® series (except Bordeaux, Citrus, Mini Strawberry Pink and Mini Rose Veined) Petunia
• Babylon®, Tapien® series Verbena.

Group 2
Can take frost to 28 degrees
• Superbells® series Calibrachoa
• Flirtation® and Flying Colors® series Diascia
• Snow Princess®, Blushing PrincessTM, Frosty Knight™ Lobularia
• Bluebird, Innocence® series Nemesia.

Group 3
Can take frost to 30 degrees

• Goldilocks Rocks®, Peter's Gold Carpet Bidens
• Laguna™, Lucia® series Lobelia
Intensia® series Phlox
• Superbena®, Tukana®, Lanai® series Verbena

We know this method can help growers maximize their profits by using empty space, increasing turns and even lowering some input and labor costs.

If you are thinking about trying outdoor growing, feel free to contact us and we can give you more detailed information on our practices and setup. We have literature, a reference guide, and are available for advice calls. We are happy to help.

Brian Bourdon has worked for Four Star for 14 years and supervises production with contract growers. To contact Brian, call 734-654-7476 or email

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