Zinnias are well-known annual flowers, primarily recognized for their easy and fast growth. Their wide range of growing habits contributes to their popularity, as they can range from short and bushy to tall with a singular stalk. Regardless of their growing habit, Zinnias are prolific bloomers. They belong to the aster family and are native to Mexico and Central America, thriving particularly well throughout the South.
Photo: De’Anthony Price
Zinnia Characteristics
There are three distinct types of Zinnias based on floral structure: single, double, and semi-double. The different floral structures do not necessarily correlate with plant habits. ‘Single’ refers to flowers that have only a single row of petals, with the center of the flower clearly visible. ‘Double’ Zinnias have multiple rows of petals, and the center is not clearly visible. ‘Semi-double’ cultivars exhibit a combination of traits, with flowers having multiple rows of petals while still maintaining a clearly visible center.
Pollinators and Zinnias
Zinnias are great for attracting pollinators, especially butterflies. Interplanting zinnias between rows of vegetables or as a border around vegetables is a great way to attract more pollinators to your garden. There are a few guidelines available for attracting butterflies to your yard using zinnias. The taller varieties are better than dwarf or compact cultivars, and those with wide, flat blooms provide a larger landing surface. Flowers should have prominent yellow centers (disc floret); double bloom varieties make it difficult for butterflies to access nectar. It is also possible that some varieties attractive to butterflies produce a larger quantity of and/or better-quality nectar than others.
Photo: UF/IFAS
Planting Zinnias
Zinnias perform better in garden beds than containers and, due to their ability to grow so quickly, can be direct seeded. To direct seed, the soil temp should be at least 70 degrees and plant the seeds at 1/4’” deep. Zinnias can also be planted as transplants and should be done once the soil warms to 60 degrees. Plant spacing can be anywhere from 8 to 12 inches depending on the plant’s habit. Singular stalk varieties can be planted closer together and bushier varieties should be given more space. Zinnias prefer full sun and well-drained soil. For longer flowering, remove the old blooms.
Zinnia Management
When planting zinnias, it’s recommended to incorporate a general-purpose fertilizer with equal parts nitrogen, phosphorus, and potassium into the soil. Following planting, monthly fertilization with a phosphorus-rich fertilizer is advisable to encourage continuous blooming. Maintaining adequate moisture is crucial for zinnias but avoid overwatering as they thrive in moderately dry conditions. To prevent fungal diseases, water only when the top 1-2 inches of soil are dry, focusing on watering the base of the plant rather than the foliage whenever possible. Powdery mildew is a common issue with zinnias, but it can be managed by applying a fungicide when necessary. However, it’s best to prevent this problem by ensuring good air circulation and avoiding wet foliage.
Photo: De’Anthony Price Diseased Zinnia
Zinnias as Cut Flowers
Zinnias, known for their vibrant charm, make delightful cut flowers that can brighten up indoor spaces for a week or longer. For optimal longevity, harvest the blooms when their centers are just beginning to unfurl fully. Trim away lower leaves and promptly place the cut ends into water-filled vases. Regularly refreshing the water helps prevent the growth of algae. When it comes to drying zinnias, double-flowered varieties are preferred as they tend to maintain their shape better than single forms. While all colors undergo slight changes during drying, cutting stems at their peak, removing leaves, and hanging them upside down in bundles away from direct sunlight facilitates the drying process effectively.
Unlike areas with cooler climates, North Florida’s weather is a bit of a rollercoaster. Where the traditional four seasons allow for one growing season, the panhandle’s temperature changes create two growing seasons – spring and fall. During the winter, temperatures fall too low to keep plants happy, so those who expect to grow tropical plants in Florida may be disappointed. During the summer, the heat and humidity climb to levels that even plants can find stressful! Many of our vegetable crops simply can’t handle the extremes and wither away.
There are a few edible plants we can grow, however, that don’t seem to mind the hot weather. If you simply can’t live without a productive garden during the summer, you might consider trying these:
Also called Southern peas, black-eyed peas, or field peas, these are known for their ability to produce a crop despite the harshest of conditions. Actually a bean rather than a pea, they take 65 to 125 days to grow to full maturity, depending on variety. Because they are a nitogen-fixing legume, they have also been used as a cover crop.
Malabar Spinach. Photo Credit: James M. Stephens, UF/IFAS
Popular in Asian countries, Malabar spinach is actually a vining plant unrelated to true spinach. It grows quickly and is edible both raw and cooked, though some people may not appreciate its mucilaginous texture. Similar to okra’s sliminess, this quality does make it useful for thickening soups. Malabar spinach may be propagated from seed or by cuttings, which root easily. The plant also produces berries which, while not toxic, have very little flavor and tend to stain whatever they touch.
A traditional Southern favorite, okra takes the heat and keeps producing. Related to cotton and hibiscus, it grows pods that are ready to harvest after 60-70 days. Seeds have a tough exterior and need to be soaked overnight before planting. Harvest every couple of days at least for best results, as pods that grow too large become tough and fibrous.
Though they may need extra attention paid to them due to their attractiveness to pests, Seminole pumpkins are a great option for a summer planting. Similar to butternut squash, these cucurbits aren’t your traditional carving pumpkin, but they make great eating. Give them plenty of room to spread out in a sunny space. They take 120 days after planting before they’re ready to harvest, and their thick skin allows them to be stored for a long time after.
Does well in sandy soil? Check. Doesn’t mind the heat? Check. Sweet potatoes are great for our neck of the woods. Start out with disease-free slips for best results, and pick varieties such as ‘Beauregard’ that do well in our area.
Related to cowpeas, yardlong beans grow on a climbing vine. The beans themselves, as the name suggests, are contained in a pod that can reach 36 inches in length. These can be picked and cooked much like green beans while the pods are still tender.
Spending time outdoors during the Florida summer is not for the faint of heart. It’s hot! And it’s humid! Just moving around outside for a moment in the early morning causes you to break out in a sweat. Most evenings, even after the sun is low in the western sky, but there’s still enough light to enjoy the outdoors, the sweat doesn’t stop. A Floridian’s only hope is that nearby, there is a large shade tree to take cover under. In north Florida, there’s nothing more inviting than a huge live oak draped in Spanish moss for a drink of ice water and a slight breeze. If you don’t have such a spot, start thinking about planting a shade tree this winter!
A large live oak is great for shade! Credit: Dawn Reed.
In north Florida, we have many options to choose from, as we live in an area of the United States with some of the highest native tree abundance. Making sure you get the right tree for the right place is important so make a plan. Where could this tree go? Is there plenty of space between the tree and any structures? You’ll want to give a nice shade tree plenty of room – 20’ to 60’ away from structures and/or from other large trees – to grow into a great specimen. Be sure not to place a large tree under powerlines or on top of underground infrastructure. You can “Call 811 before you dig” to help figure that out. If space is limited, you may want to consider trees that have been shown to be more resilient to tropical weather. Also try and place the tree in a way that provides added shade to your home. Deciduous trees planted along your home’s southeast to southwest exposure provide shade during the summer and let in the sun during the cooler winter. However, be careful that the tree doesn’t grow to block the sun from your vegetable garden!
A density gradient map of native trees in the US. Notice where the highest number occur. Credit: Biota of North America Program.
Here are some ideas for shade trees, those trees that are tall (mature height greater than 50’) and cast a lot of shade (mature spread greater than 30’). All of these are native trees, which have the added benefit of providing food and shelter to native wildlife.
Even with this young sycamore, you’ll be made in the shade. Credit: UF/IFAS.
While it may take a while for you to relax under the shade of your tree, they can surprise you in their growth and, as they say, there’s no time like the present. If you have questions on selecting or planting shade trees, contact your local UF/IFAS Extension office.
North Florida vegetable gardeners have made it to summer and now the plants and gardeners are starting to give in to the heat and humidity. The squash has likely succumbed to squash vine borers, many of the tomato varieties are having trouble setting fruit, stink bugs are all over, and gardeners easily wilt by noon. This is a good time to use our oppressive heat to your advantage in the vegetable garden by solarizing the soil.
We have reached the peak of heat. Use it to your advantage in the garden. Source: National Weather Service.
Soil solarization is a method of pest control that creates a greenhouse to heat up the soil in an effort to drive away pests. Pests that can be reduced with soil solarization include weeds, various soil-borne fungal pathogens, and nematodes. Weed seeds can actually be killed by the increased temperatures, sometimes as high as 140 degrees Fahrenheit, while fungi and nematodes are merely driven deeper into the soil layer as they try to escape the heat. Although they are not killed, this can help vegetable gardeners as it may take these organisms 3-4 months to repopulate in high enough numbers to cause damage. Soil solarization can be considered another tool in your integrated pest management (IPM) toolbox, along with other cultural, physical, and chemical means of pest control.
A raised bed being solarized over the summer. Source: Evelyn Gonzalez, UF/IFAS Master Gardener Volunteer.
To properly execute soil solarization, the site should be in full sun and the existing vegetation removed, either by hand or with a tiller or other implement. Tilling can help loosen the soil surface and allow heat to penetrate deeper in the soil horizon. Before being covered with plastic, the area should receive rainfall or be irrigated, as the water will help conduct heat to greater depths. The next step is to cover the area with plastic. Note that this can also be done over raised beds! Clear plastic is best for maximum solar radiation penetration. Black plastic will heat up mostly on the surface and opaque plastic sheeting may not let enough light in to get temperatures high enough. The plastic should be slightly larger than the area covered, as the edges will need to be buried to create an air-tight seal. It’s recommended to leave the plastic in place for at least six to eight weeks, just in time to begin fall gardening preparations.
It’s important to monitor the site while it’s “cooking” to look for any holes that might appear. Small holes can be repaired with duct tape, while large holes or rips in the plastic may require starting over. Overlapping strips of plastic is not recommended since too much heat will be lost.
You may be wondering what happens to all of the good soil microbes. Well, unfortunately, they are also either killed or suppressed. Fortunately, researchers have found that they are able to repopulate quicker than the pest organisms, especially in soils with a good amount of organic matter.
Much more information on soil solarization can be found in these two documents:
Are you interested in growing lettuce and other leafy greens? Are you looking for tips on extending the growing season for your leafy green crop? If so, then check out this very informative instructional video by Washington County Horticulture Agent Matthew Orwat.
