Now that you are familiar with zinnias and their popularity, let’s explore the potential causes of your zinnias’ potential garden difficulties. There are numerous reasons why this occurs, and each of them is normally treated differently. Your plant might or might not be able to be saved, depending on the reason why your leaves or blossoms turned brown. Let’s examine each reason in more detail, along with possible solutions.
Alternaria Leaf Spot or Blight
Your plant may have been infected by the fungus Alternaria zinniae if you start to see small, dark, round, reddish spots with white to grayish-white centers on the leaves of your zinnias. Unfortunately, a wide range of flowers are impacted by leaf spots.
These patches will enlarge, take on an uneven shape, and change color from dark red to dark brown or purple. On the interior of the diseased lesion, you could detect dark, concentric circles. As the plant tissue begins to decompose, the spots may eventually turn into holes.
Alternaria leaf spot can cause severely infected zinnia plants to swiftly lose their green leaves and turn brown and shrivel. Brown lesions may also appear on the stems. If stem lesions are severe enough, they can girdle the stem, which will cause the upper part of the plant to wilt and eventually die off since the circulatory system is cut off.
How to Fix:
If they are minor or moderate, fungal infections in Zinnias may usually be handled. Use horticultural oils, such as jojoba or neem oil, to solve the issue. If less effective solutions like neem oil are unsuccessful, a commercially available fungicide can potentially be a possibility.
Powdery Mildew
The fungus that causes powdery mildew is highly prevalent on zinnias in the late stages of the growing season. The leaves will develop a white, powdery growth that will eventually cover the stems and blooms. Typically, powdery mildew spreads up the plant.
At the plant’s base, severely affected leaves start to turn brown and eventually die. Plants that are severely affected will become weak and stop growing.
Like blight, powdery mildew can be treated with neem oil or a commercial fungicide. However, it works best when applied early in the season, before powdery mildew has a chance to develop. You might be forced to pull your badly affected plants and replant them if that is your only option.
Cercospora Leaf Spot
Cercospora leaf spot and Alternaria leaf spot resemble one other strikingly, making them readily confused. Both Alternaria leaf spot and cercospora leaf spot can frequently happen together.
The fungus Cercospora zinniae is what causes cercospora leaf spots, which are rather large, circular, dark purplish, with gray to gray-white centers. As rot advances, the plant tissue may come loose from the cores. Leaves that have been severely diseased will quickly turn brown and shrivel.
A commercial fungicide is used to treat the fungus that causes leaf spot. Neem oil also has potential. When compared to other fungal illnesses, leaf spot is often easier to treat, and if caught early enough, your plant will have a greater chance of surviving.
Lack of Water
Zinnias don’t need a lot of water at first, but there comes a time when they do. It’s probably due to a lack of water if you’ve been facing drought conditions and your zinnias are beginning to perish.
Wilting is one of the first indications that your plants aren’t getting enough water. If the situation is not fixed, the leaves will droop, shrivel, and eventually start to turn brown and die. If the plant is given enough moisture to recover, wilting can be swiftly reversed.
It is probably too late to save the plant if it has already started to turn brown and die from a lack of water. Drought stress can have long-lasting and irreversible consequences on a plant’s growth, even if it survives.
Set up a regular watering routine. Changing your watering regimen should bring them back quickly as long as the plant isn’t going brown. If the leaves on your zinnia are brown and crispy, it’s probably too late to salvage it.
Waterlogged
More frequently, zinnia plants can also become waterlogged and experience problems. Why does this matter? It indicates that either the soil is not draining properly or that the soil has received too much water. While water is essential for plants, oxygen is also necessary for plant roots.
When the soil is waterlogged, the pore space—the area between soil particles—is completely filled with water, leaving the plant roots with little to no access to oxygen. The roots will start to deteriorate from a lack of oxygen, and you’ll start to see the edges of the plant leaves turning brown.
If you’ve been routinely watering your zinnias and you realize this is happening, stop. Drain the soil, please. Always pick a spot in your garden that has good drainage when planting zinnias to avoid problems from wet circumstances.
Since too much water can also be a problem, the answer is similarly straightforward. Avoid overwatering them or amend the soil to make it more permeable. In essence, a plant that is soggy is drowning. The solution is usually as simple as adjusting our water routine.
Frost
Zinnias enjoy heat. They are an annual that enjoys the summer! They therefore don’t withstand the majority of cold temperatures, like many annuals. Your zinnias will continue to bloom long into the fall, but suddenly the first frost of the year will arrive.
Your zinnias will abruptly turn brown overnight as a result of the freezing temperatures when that occurs. Your zinnias are probably done for the season if the frost wasn’t too severe or if another frost doesn’t come around for a while. However, this is not always the case. After all, everything nice has to end.
There isn’t a genuine technique to stop zinnias from disappearing in the winter. Covering the plants in the winter when it becomes too cold is the best approach to prevent severe frost damage. Depending on your environment, your flowers won’t normally blossom past October.
Setting Seed
Zinnias are annuals once more. This indicates that they go through their entire life cycle in a single season or year. The seeds will begin to sprout in late spring, the plant will start to blossom in the summer, and when it has bloomed profusely, it will start to set seed.
Gardeners can prevent this by deadheading the faded flowers to encourage new blooms, but occasionally we could miss a few blossoms or perhaps we’re not bothered with that level of upkeep.
Up until the entire flower head has turned ugly, crunchy, and brown, you’ll see that the flower petals will fade away and turn brown. Not to worry! Simply grasp this withered flower head and gently press it between your fingertips. There are a large number of brown zinnia seeds. One of the few instances when your zinnias turning brown is beneficial is right now!
The life cycle of the zinnia includes setting seed. There isn’t really a cure for this because annual plants finish their life cycle in a full year. However, when it does, it can help you initiate more spring flowers and is actually a wonderful thing!
Bacterial Leaf Spot
This leaf disease is caused by the bacteria Xanthomonas campestris. At first, very small, diffuse, translucent specks with wide, yellowish haloes will form. The patches will gradually start to expand in wet environments.
The spots will then develop a reddish center and take on an asymmetrical circular or angular shape. The lesions could combine to create sizable dead regions. Small brown spots may appear on the flower petals, and if the infection is serious enough, the entire flower head may become disfigured and begin to rot.
Similar to fungus, bacterial leaf spot can be treated. Neem oil, fungicide, and even a baking soda solution can be used to cure it. These remedies are more natural and frequently more accessible than other, less practical, solutions.
Aster Yellows
The phytoplasma that causes aster yellows is spread by leafhoppers. Members of the Asteraceae family, which includes zinnias, are impacted by this organism. Small, deformed flowers and yellow, stunted growth are symptoms.
The plant will start to die back and turn brown as the infection worsens. After infection, the plant will never recover. If you see any of these signs, get rid of the sick plants right away and either burn them or bury them.
It is very challenging to get an aster yellow infection under control. You will probably need to remove the diseased plants from the area if your zinnias have Aster yellow. Since this illness spreads quickly, there is little purpose in attempting to treat it once it has begun. Aster yellow has no known causes, symptoms, or treatments. The plant must be removed, and you must pray that it does not spread to other plants.
Root and Stem Rot
Root and stem rots are brought on by fungi like Pythium, Rhizoctonia, and Fusarium that live in soil. At the base of the plant, dark brown, gray, black, or red patches are the earliest signs of root and stem rot.
The plant may wilt, die back, or lose vitality as a result of the rotting of the tips of roots beneath the soil’s surface. The inside of the stem may start to turn brown or the stems may turn dark and spongy.
Often, it is too late for the plant to recuperate once symptoms start to appear above the soil line. The most common times when root and stem rots happen are in the chilly springtime when it’s very humid or soggy.
Root rot is challenging to heal. When zinnias reach a certain point, it’s essential to completely remove the plant since root rot can spread. If there is only one plant, the best course of action is to thoroughly wash the plant’s roots with water. Eliminate any soil that might have come into contact with the diseased regions. After applying a fungicide to the roots, replant them.
How can you revitalize zinnias?
One of the simplest flowers to plant, zinnias grow quickly and provide a lot of blooms. Additionally, they will continue to bloom right up until the first fall hard frost. Consider trying zinnia flowers this year to add a huge splash of color to your yard.
About Zinnias
Since zinnias are annuals, they will only produce blooms and seeds for one season before dying. The original plant will not reappear the following year. They are excellent for use as a cutting flower or as food for butterflies since they have vivid, solitary, daisy-like flowerheads on a single, tall stem.
Types of Zinnias
Zinnia elegans, the most widely grown zinnia species, has been developed to produce a large number of distinctive variants.
Single, semidouble, or double zinnia blooms are the three most common varieties. The number of petal rows and whether or not the flower’s center is visible serve to distinguish between these forms:
- A single row of petals and the center are both visible on single-flowered zinnias.
- Petal rows abound on double-flowered zinnias, and their centers are hidden.
- Between the two are semidouble-flowered zinnias, which have several rows of petals but discernible cores.
In addition to these shapes, zinnia flowers also occur in “beehive,” “button,” and “cactus” forms. Additionally, the plants themselves come in various heights: taller types function best as a garden bed’s background, while shorter varieties are useful as a border. There is a zinnia for every garden, in fact!
In an annual or mixed border garden, plant zinnias. Smaller zinnias work well as window boxes, edging, or in other containers.
To have a lot of flowers all season long, choose a place that receives full sun (6 to 8 hours of sunlight every day). Additionally, later in the season, foliar diseases like powdery mildew can be avoided by planting in an area with sufficient air circulation.
Although zinnias can grow in a variety of soil types, they prefer organically rich, well-draining soil. The optimal pH range for soil is between 5.5 and 7.5. The blooms will grow more quickly if compost (humus) is added to the soil. Find out more about soil improvements and getting the soil ready for planting.
When to Plant Zinnias
- Because they dislike being transplanted, it is advised that you start your zinnia plants from seed directly in the garden bed. If the correct circumstances are present, they will develop quite quickly from seed.
- It should be noted that zinnias can be grown from seed inside if you like. Just make sure to transfer them gently and young.
- Because zinnias are delicate to frost, wait to plant them until after the last frost in your area. See the frost dates in your area.
- Zinnias can tolerate daily temperatures as low as 60F (16C), although a range of 7484F (2328C) is ideal.
- To prolong the flowering time, sow a new crop of seeds every week or so for a few weeks.
How to Plant Zinnias
- Depending on the kind, place plants 4 to 24 inches apart. (Many common kinds are planted 2 feet between rows and 6 inches apart within the row.) For information about each variety, consult the seed packet’s back.
- Plant zinnia seeds no deeper than 1/4 inch.
- The majority of zinnia cultivars will produce seedlings in just 4 to 7 days, but it may take up to two months or more for blooms to appear (depending on planting site and climate).
- To promote air circulation, thin seedlings when they are three inches tall, spacing them 6 to 18 inches apart. As a result, powdery mildew is less likely to grow.
- To promote development and blossoms, keep the soil’s moisture level moderate and apply a mild fertilizer.
- Deadhead zinnias once they have finished blooming to facilitate the development of new blossoms.
- Since zinnias are annuals, they will perish with the first fall hard cold. Let the final blooms of the season fully mature before dispersing their seeds if you want them to reseed.
Still not sold on zinnias? In your garden, try them out for the following six reasons:
- With cultivars from the Dreamland Series, you can have a full-sized flower on a little plant. These zinnias are compact and dwarf, with stems that are 812 inches tall and totally double flowerheads that can be up to 4 inches across with a variety of colors.
- The dwarf, spreading cultivars of the Thumbelina Series have weather-resistant, solitary or semi-double flowerheads in a variety of hues. Their stems can reach a length of 6 inches, and their petals are 1-1/4″ wide.
- One of the largest and tallest of them all, the State Fair Series has huge, double flowerheads that measure 3 inches in diameter. Stems can reach a height of 30 inches.
- Typically, it takes zinnias 60 to 70 days from seed to flower (though it depends on conditions and variety). They are fantastic in a bunch of flowers!
- The tiny, narrow-leafed zinnias are great for hanging baskets and also make lovely dried flowers.
- Zinnias are considered to represent memories of those who have passed away. Discover more about the significance of flowers here.
- Zinnias may be harmed by bacterial wilt, powdery mildew, and bacterial and fungal spots. To prevent illness, keep leaves from getting too damp and correctly space your plants.
- Problems can also be brought on by caterpillars, mealybugs, and spider mites. Spraying should be avoided unless there is a real infestation because some leaf damage is not a problem.
- Thanks to their resistance to deer, zinnias may be able to prevent surrounding flowers from being eaten.