Two Tips for Top Flowers

May 24th, 2016

Jack Barnwell, the plantsman and landscape designer behind many of the gorgeous gardens on Michigan’s Mackinac Island, offers two tips for milking the most out of summer annual flowers – superior varieties and a lot of feeding.

Jack Barnwell talking annuals to our tour group.

If your flower gardens peter out by mid-season or just never measure up to what you see in public gardens, those two factors likely explain it.

Barnwell and his crew plant annuals by the tractor-trailer load and need to get them up to speed right off the bat for the tourists who flood the island for a hectic 3-month season.

You won’t find them using any seed-grown marigolds or the kind of cheapo petunia 6-packs that Grandma grew.

Barnwell has found that breeders have come up with new varieties in the last 10 to 20 years that are light years ahead of what people used to grow. He leans heavily on the Proven Winners line that come mostly in singular 4-inch pots that sell for $3 to $5 per plant.

Yeah, that’s more than you’ll pay for those 4- and 6-packs at the grocery stores and box stores. But if you’ve ever grown those side-by-side with the good stuff, you’ll see the difference.

“Spend the money,” Jack told the tour group I took on a jaunt through great gardens of Michigan last week. “They perform so much better.”

I agree. Check out 10 annuals that I like best in a post I wrote on Top 10 Annual Flowers. And while you’re at it, see the 10 that I don’t care for in a post on Bottom 10 Annual Flowers.

One way to hold down cost while maximizing performance is to use your superior annuals in pots. You’ll need just a few of them there to get big impact – especially when you use large and showy pots in key areas.

Annuals in hanging baskets and window boxes also give you the most return for your flower dollar.

Or plant patches of annuals in mixed gardens of perennials, grasses and shrubs as opposed to planting large bands of annuals.

That’s the strategy Jack uses in most of the Mackinac gardens. Annuals are a part of the gardens of “cottagey” perennials, hydrangeas and colorful-leaved plants – adding summer-long color to bridge the gap between the perennials’ shorter bloom times and creating a lushness that some call the “Mackinac Island look.”

If you’ve never seen Mackinac Island, it’s a quaint island resort in upper Michigan that’s most famous for its grand scenery and policy of no cars.

Many of the shops, restaurants and homes have colorful cottage-style gardens that are becoming nearly as iconic as the island’s horse-drawn carriages and fudge shops.

Plants take center stage the last weekend of each August in a Grand Garden Show the island and its Grand Hotel stages to showcase some of the latest, greatest plants.

Getting back to growing annuals, if you’re still not convinced that variety choice makes such a big difference, pay a visit this summer to the Penn State Trial Gardens in Lancaster County.

Penn State trials hundreds of varieties of plants every summer at its test plot in Lancaster County.

Penn State and the floral industry grow hundreds of different flowers every summer and rate their performance to help determine which ones make it to market.

You’ll see dozens of petunias or verbena varieties, for example, growing side by side under the exact same conditions and care. But while some are blooming their heads off in solid balls of color, a neighbor might have half the flower power – or be hanging on for dear life by August.

A visit there is free and open to the public. If you can’t get there, check out the flower-by-flower ratings that Trial Director Sinclair Adam posts on the trial gardens’ website. And check out the PennLive slide show I posted a few weeks ago on Sinclair’s top 10 flowers that he’d recommend.

The second part of Barnwell’s flower success is fertilizer.

He says his Mackinac staff regularly fertilizer flower beds with a balanced liquid fertilizer (they use Proven Winners’ brand of that, too) mixed in a sprayer and sprayed over the leaves.

This is called “foliar feeding,” and Barnwell says plants can take up more nutrients through the leaves than most people realize. In other words, roots aren’t the only way plants get nutrition.

Mackinac’s annuals in pots and flower baskets get fertilizer every day along with their daily early-morning watering.

“They’re like people… they love to eat,” Barnwell says.

It’s almost impossible to over-fertilize plants in pots because the frequent watering leaches nutrients down and out of the pots. That’s why frequent diluted fertilizer is a better route to success for containerized plants than giving a full-strength fertilizer once a month.

In the ground, monthly fertilizer usually is enough – especially if you’ve topped your beds with compost each spring or fall and/or worked a timed-release or granular organic fertilizer into the soil at planting.

Annual flowers – and annual vegetables such as tomatoes, peppers and cucumbers, for that matter – are all heavy feeders because they’re trying to complete their entire life cycle in a single season.

Trees, shrubs, bulbs and perennials are much better at manufacturing and storing energy for later use because they’re adapted to living many seasons. Most of those do fine with a single shot of fertilizer per year – if even that.

Now’s still a good time to add annuals to your 2016 landscape. You can keep planting them well into summer so long as you keep them well watered.

Prices sometimes even go down after Memorial Day as garden centers try to clear out what wasn’t bought during the Mother’s Day rush.