Since sunflowers that are planted in midsummer often flower on shorter stalks, sow your giant sunflowers earlier-as soon as all danger of frost is past and night temperatures are above 50 degrees Fahrenheit both day and night. In the shorter-season, cold winter areas of the U.S., this means late May to early June. The ideal spacing in rows for giant sunflowers with large seed heads is 20 in. apart. If you plant closer, you might get taller stalks but smaller heads. If you plant farther apart, the seed head may be larger, but possibly too heavy for the stalk to bear. If you have limited space, Tom recommends sowing in a small clump that will eventually be thinned to one plant.
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Home / Gardening Resources / How to Grow the Biggest, Tallest Sunflowers: Tips from an Expert
How to Grow the Biggest, Tallest Sunflowers: Tips from an Expert
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By guest author Alice Formiga
To learn the secret of growing sunflowers to record-breaking sizes and heights, I turned to Dr. Tom Heaton, the world’s foremost sunflower breeder and Renee’s Garden sunflower seed supplier. Tom has been breeding sunflowers for 30 years and has revolutionized the market by introducing a dazzling array of new sunflower forms and colors to the seed trade. His wholesale seed production company specializes in long-stemmed pollenless cultivars for the cut flower market and home garden. He has developed varieties in a full spectrum from burgundy and ruby red to orange, peach, apricot, bright yellow, to fiery bicolors. Most of Renee’s Garden sunflower varieties are from his exuberant collection.
Fortunately for home gardeners with giant sunflower aspirations, Tom has also focused on breeding the ultimate tall competition varieties (“Giant Edible Sunzilla” and “Heirloom Titan”). Each year, Tom saves his longest stalk and largest seed head of this variety in his garage to measure against the following years. He currently prizes a 17-foot stalk and a 24 in. seed head! In this article, Tom has generously agreed to share his method of growing giants like these in your home garden.
First – Choose the Right Variety
Despite the growing popularity of new color introductions, the sunflowers that grow largest are those most of us still imagine first when thinking of sunflowers. These have tall single stalks with big flower faces of golden yellow petals and chocolate brown centers that ripen into heavy heads filled with seeds that birds will love.
I asked Tom why serious competitors should grow his variety instead of traditional varieties of large sunflowers like Mammoth, Russian Mammoth or California Greystripe. He explained that the seeds in Sunzilla are hybrids, developed to be uniform and consistently reliable – so that when you thin seedlings, you needn’t worry that you may have just uprooted your most potentially vigorous specimen. While older varieties often become top-heavy and fall over in wet or windy weather, Sunzilla has been selected for a strong, thick stalk to support its heavy head. In ideal growing conditions, it reaches heights of 16 feet or more and produces huge seed heads.
HOW TO PLANT SUNFLOWERS STEP BY STEP
We know sunflowers as the picture-perfect tall, blonde plants greeting us as we drive through the countryside. But it turns out sunflowers come in many different varieties. Some of them grow to be 3-meters tall, others get to 50 cm and stop growing – just perfect to put in a vase on the window sill. The yellow colour is optional as well. Sunflowers come in orange, brown or dark red hues too. So even before you decide where to plant your sunflowers, the first thing to do is choose the type of seeds you think will make a bigger impression on the kids in the family.
Or why not plant different ones in different pots? Don’t forget to label them though, as they come with fun names such as ‘Teddy Bear’, ‘Big Smile’, ‘Sundance Kid’, or ‘Suntastic Yellow Sunflowers’.
Decide when to plant your sunflower seeds
One of the first things to know about sunflowers is that they don’t like frost at all. So, wait until the last spring frost is over before you plant the sunflower seeds. This means it’s a great project to start in the spring, anytime between the middle of April and the end of May. If you’re planting the seeds outdoors make sure you wait until the end of May before you transfer them from your pot.
Look for sunny places in and around your home. A window sill or a balcony are great places where you can put the pot with the baby sunflower seeds in. For taller varieties of sunflowers you will have to eventually get them into a bigger pot outdoors, so make sure you reserve the sunniest spot in your garden for that moment.
Put together a list of all the things you will need
Luckily planting a sunflower is easy and it won’t require many trips to the supermarket. All you need are a few easy-to-find supplies:
- Sunflower seeds
- Clear plastic bags
- Pots
- Compost
- Cane
- Labels
