Love Gomphrena? Here’s How To Grow It From Seed

A growing awareness of the environmental impacts of the traditional cut flower industry is encouraging many sustainability-minded North Texans to grow their own cut flowers at home. One old-fashioned flower quickly becoming a favorite of North Texas’ hobby floral farmers thanks to innovations in breeding and its low input requirements is gomphrena.

Let’s take a look at what it is and what it takes to grow gomphrena successfully from seed.

What is gomphrena?

Gomphrena (Gomphrena globosa), also known commonly as Globe Amaranth, is in the same family as amaranth and celosia and originates from Central America.

A favorite of pollinators, gomphrena is a multi-branched plant that grows to around two-feet high and is topped with globe-like florescences in shades of red, pink, purple, and white. No matter drought nor 100+ temperatures, gomphrena blooms in the Dallas-Fort Worth area from late spring through first frost earning it a well-deserved reputation as one of the toughest annual flowers for North Texas cutting gardens.

Tips for starting gomphrena by seed

Though very easy to grow once transplanted, gomphrena can be a bit finicky when started by seed. Here are some tips for seed-starting success:

1. Start seeds indoors with a heat mat

Gomphrena seeds can be direct-sown outdoors, but it is easier to start gomphrena indoors. Starting indoors gives you more control over seedling growth, but most importantly, it allows you to provide supplemental heat with a seedling heating mat. It’s also a good way to get a head start on the season.

With a heat mat, I can get germination in as little as three days with soil temperatures between 75 and 80 degrees.

(Here are the tools that I use to start seeds indoors.)

2. Sow more than you need

No matter the seed company nor the variety, my gomphrena success rate from seed to transplant is around 25%. So, for every four seeds I sow, only one of those will make it all the way into the garden. Though this may seem really low, keep in mind that gomphrena plants will grow to be quite large in one season and bloom continuously.

Their success rate is fairly low for two reasons:

1. Gomphrena has a low germination rate. It is rare that all of the gomphrena seeds I sow germinate. I believe my current average is 50-75%.
2. Gomphrena seedlings grow slowly. I often start gomphrena at the same time as cosmos and marigolds, but it can take 2-3 weeks longer for the gomphrena to reach ideal transplant size. Because it grows so slowly, there is a greater risk of the seedlings dying for various reasons including overly saturated roots due to over-watering or cool temperatures.

3. Don’t pot up too quickly

Because gomphrena seedlings are slow to take off, resist the urge to pot them up too quickly or into pots that are too large. After losing several seedlings to root rot after moving them from a 72-cell tray into 3.5″ pots, I’ve had better success with 2.5″ pots. I’m also very careful to use a well-draining potting mix.

4. Hold until garden soil temperatures are ideal

As mentioned previously, gomphrena plants love the heat. That’s why they grow so well in our dry and hot North Texas summers. To prevent your gomphrenas from stagnating in the garden, hold your transplants until soils are warm enough. Soil temperatures should be at least 65 degrees before planting out. (Here is a good resource for estimating your average soil temperature.) In North Texas, soil is typically warm enough by mid-April, but best growth will begin to occur in May.

Once gomphrena is transplanted it requires very little care. It is drought and heat tolerant, and does not seem to show a preference for fertilizer, although I do like to provide an all-purpose fertilizer at least once or twice during the growing season to maintain bloom.

When to start gomphrena in North Texas

Start gomphrena indoors 6-8 weeks before the average last frost date (March 12 is average last frost or Dallas-Fort Worth). Or wait until early April to plant gomphrena seed directly in the garden.

Commercial availability of gomphrena seeds is low relative to demand so order your gomphrena seeds as early as possible to avoid sell-outs.

Popular varieties of gomphrena

Gomphrena growing guide

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Callie Works-Leary

Founder of The Dallas Garden School, Callie is an expert garden educator with 17 years of personal and professional gardening experience. She specializes in growing food, small-space gardening, managing community gardens, and plant propagation. She has an MBA from Southern Methodist University, a bachelor's degree from Skidmore College, and served as a horticulture intern for the Dallas Arboretum & Botanical Gardens. Callie is a member of the Native Plant Society of Texas, The Herb Society of America, the National Garden Bureau, and is a Certified Texas Master Gardener.

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