An armful of zinnias are the epitome of the summer. These cheerful blossoms, which come in a vibrant spectrum of colors, are a must-grow for any flower enthusiast.
Since they are among the simplest cut flowers to raise, they make an excellent first crop for new growers and are a consistent, prolific performer for the majority of flower farms and gardeners.
Since the beginning, we’ve grown zinnias, and each year, I fall more and more in love with them.
Because they dislike the cold, zinnias prefer to be planted once it has warmed up a little. However, in chilly Washington, we start our plants in 72-cell trays in the greenhouse 4 to 6 weeks before our last spring frost. Many gardeners in warmer regions of the world are successful at direct seeding their zinnias out into the field.
Around the middle of May, after the weather has sufficiently warmed up and any threat of frost has passed, plants are tucked into the field. On our farm, we work to give each blossom the greatest possible start. Find out more about preparing the soil here.
After preparing the planting beds, we install four drip irrigation lines that are spaced about a foot (30.5 cm) apart, and we then cover the beds with a layer of pre-burned landscape cloth to keep weeds at bay. With five rows per bed, plants are spaced 9 inches (23 cm) apart.
Plants can grow enormously large and require some sort of support if given suitable soil and a consistent supply of water. We employ a layer of horizontally stretched Hortonova netting that is 12 inches (30.5 cm) above the surface. Metal hoops that we bent using our Johnny’s Quick Hoops Bender are used to hold the netting in place. Any stake, whether made of wood or metal, will do. As the plants develop, they push through the netting grid and receive the support they require.
Because they prefer the heat, zinnias must be grown in full sunlight. I always grow them in cloth for the extra heat in addition to choose a sunny location.
Since they are cultivated in such rich soil, there hasn’t been a problem with disease, which I was concerned about when we first started planting zinnias this close together. Every two to three weeks, we succession sow zinnias to provide a constant supply of these lovely blossoms throughout the summer.
Pinching your zinnias when they are young is the key to getting the longest stems from them. Here is how to accomplish it: Use sharp pruners to remove the top 3 to 4 inches (8 to 10 cm) of the plant when it is between 8 and 12 inches (20 and 30 cm) tall, right above a set of leaves. This instructs the plant to grow more stems above the point of the cut, increasing both bloom production and stem length. The image up top shows pinching with a different kind of plant.
Deadhead any spent blooms if you don’t routinely pick your zinnias in order to direct the plant’s energy toward growing new blossoms rather than setting seed.
Zinnias must be selected when they are completely ripe in order to stay fresh in the vase. Use the to determine if a zinnia is ready to be harvested “Waggling test Just gently shake the stem while holding it approximately 8 inches (20 cm) down from the blossom head. The stem is not ready to be cut if it droops or bends. It is time to harvest if the stem is rigid and continues to stand upright.
Zinnias are regarded as a “Adding a few drops of bleach to their water will help clean up soiled flowers. Given that the flowers are quite sensitive to cold, do not place them in the cooler.
There are an astonishing variety of zinnias available in every imaginable size, color, and shape. Whatever your requirements, there is undoubtedly a zinnia for you.
Consider how many options there are if you’re looking for flowers in the peach-salmon color spectrum, for instance.
Giant Salmon Rose, Cinderella Peach, and Queen Lime Orange are in the top row, from left to right.
sowing zinnia seeds
Because zinnias are known for hating root disturbance, it is better to direct seed into finely tilthed, easily draining soil. If you want to sit outside in the evenings, wait until May or June to do this. It’s still too cold if the evenings are cool enough to make you want to eat dinner indoors rather than outside. Your zinnias should be planted in a greenhouse or polytunnel if you reside in a region of the country where eating outside only happens once every five years.
Choose a sunny area, scatter two or three seeds there, 5 cm (2 in) apart, and space each cluster about 30 cm (12 in) away. When the seedlings appear, thin them out until there is roughly one plant every 12 inches (30 cm). Pinch the tips out to promote branching. Individual stakes work best for supporting zinnia plants. Use pea or jute netting to cover your young plants and support it between bamboo or hazel canes if you’re growing them in a vegetable or cutting garden for picking. The zinnias are barely supported and will climb up and through the grid. The netting will soon be covered in fresh leaves and foliage.
Staking them correctly is worth the work because they benefit immensely from early straight growth. They will never develop or bloom as effectively when supported vertically as they will if they collapse.
growing zinnias in a pot
When the nights are warm in late May or early June, you can plant zinnia seedlings that you’ve purchased or grown yourself into containers (earlier if you keep the containers under glass for a few weeks). Before planting, wait until the seedlings have two or three sets of genuine leaves.
Choose your pot size wisely because different zinnia types require different sized containers. Put peat-free, freely draining compost inside. Plant no more than three seedlings in a pot with a diameter of 35 cm (1 foot), but this will actually depend on the variety you have, so read the instructions for each type.
4-6 weeks after planting, or around the time the fertiliser in the compost is depleted, water thoroughly and fertilize with a liquid fertilizer.
Can I trim the leggy zinnias back?
I was apprehensive about cutting back my tiny Zinnia plants. Everyone advised cutting them back to help them branch out and produce more flowers, and after doing a lot of research and watching several videos on YouTube, I decided to follow their advice. I shuddered and removed them all. Let me tell you, cultivating zinnias was the best choice I ever made! They multiplied like weeds! I have enormous, overgrown plants that have simply continued to bloom all summer!
Zinnia plant pruning is quite simple. Simply wait until they are between 10 and 12 inches tall; you want to ensure that they have a few sets of leaves. You should remove the plant tops when they get to this stage. With a good pair of pruners, I removed the top two sets of leaves by about 4 inches. (See the image above) It’s that simple to prune zinnias!
My zinnias are leggy; why?
Leggy seedlings are mostly brought on by a lack of light. It may not be enough light coming through the window where you are growing your seedlings or the grow lights you are using may not be close enough to the seedling. The seedlings will become leggy either way.
This occurs as a result of how plants respond to light naturally. Plants always expand toward a source of light. The same factor that causes crooked houseplants also causes leggy seedlings. The plant strives to heighten itself in order to get closer to the light because it is too far away for it to survive as it grows in the direction of the light. An unfortunate fact is that a plant can only grow so much. The width of the stem is sacrificed in order to acquire height. You end up with lengthy, floppy seedlings as a result.
There are various reasons why leggy seedlings are a concern. First, moving seedlings outside will present challenges if they are too tall. They can’t withstand weather conditions like wind and heavy rain as well because they are thin and floppy. Second, weak seedlings have a difficult time developing into powerful plants. Thirdly, seedlings that are toppling over may be more susceptible to illness and pests.
How can leggy zinnia seedlings be fixed?
Giving leggy seedlings enough light right away is the greatest cure! This can entail upgrading to a stronger light, lowering your present light closer to the seedlings, or using an additional grow light if you don’t already have one. A smaller, brighter amount of space becomes available beneath a light’s canopy as you lower it. As a result, to adequately illuminate a large number of seedling trays, it may be necessary to use multiple lamps or a single larger unit. Otherwise, those who linger at the edge are excluded! In such situation, rotate various trays in front of the light each day until you can supply more.
Why do my zinnias grow so slowly?
Zinnias can be grown from seed that is sown early indoors and moved outside after a frost, or from potted plants or seeds sown directly in the ground after a frost.
Indoor Seed Sowing
- Utilizing a seed starting kit, sow indoors 5-7 weeks before to the date of outdoor planting in the spring.
- plant seeds A quarter-inch deep in seed starting solution
- At 70–75 degrees Fahrenheit, keep the soil moist.
- The seedlings appear in 7–10 days.
- As soon as seedlings appear, give them lots of light on a sunny windowsill or grow them 3–4 inches beneath 16–hour-per-day fluorescent plant lights that are off for eight hours at night. As the plants get taller, turn up the lights. Because they will become too hot, incandescent bulbs will not function in this process. Do not leave lights on continuously for 24 hours; most plants need a time of darkness to flourish.
- when they have two sets of leaves, thin to one seedling per cell.
- Seedlings don’t require a lot of fertilizer; feed them when they are 3–4 weeks old with a starter solution (half the strength of an indoor plant food), as directed by the manufacturer.
- After the first frost, transplant hardened-off seedlings into the garden.
- Seedling plants must be “hardened off” before being planted in the garden. By relocating young plants to a protected area outside for a week, you can acclimate them to outside circumstances. At first, be sure to shield them from the wind and the light. If frost is expected at night, cover or bring pots inside; then, in the morning, reintroduce them to the outdoors. The plant’s cell structure is toughened during the hardening off process, which also lessens transplant shock and scorching.
Direct Sowing in the Garden
- After any threat of frost has passed, direct-sow seeds in ordinary soil in full sunlight.
- The top 6 to 8 inches of soil should be cleared of weeds, and then it should be leveled and smoothed.
- The majority of plants do well in soils that have had organic matter added. Compost is a beautiful organic material that can be applied to your planting area whenever you like. It has the perfect pH level and nutrient balance. If compost is not available, topdress the soil with 1-2 inches of organic mulch after planting; this mulch will break down into compost over time. Following the growth season, a soil test will reveal what soil amendments are required.
- equally space the seeds 12 inches apart, then top with 1/4 inch of fine dirt.
- Lightly press the soil with your hand, water, and maintain an uniform moisture level.
- In 7–10 days, seedlings will start to show.
- When seedlings are 1-2 inches tall and 8–24 inches apart, depending on the variety, thin them.
Gardening: Planting
- Choose an area with good, rich, moist organic soil that receives direct sun.
- Turn the soil under to a depth of 8 inches to prepare the bed. To get rid of grass and stone clumps, level the area using a rake.
- For each plant, create a hole that is sufficiently large to hold the root ball.
- Set the top of the root ball so that it is level with the dirt around it. Up to the top of the root ball, cover with soil. Your hand should firmly push the earth down, leaving a small depression to hold water around the plant.
- Water deeply until a puddle appears in the saucer you have made. As a result, there is strong root-to-soil contact and the plants become established.
- Use the plant tag to indicate its location.
How to Grow
- Keep weeds under control while the plants are growing. Weeds compete with plants for water, space, and nutrients, therefore keep them in check by frequently cultivating or by using a mulch to stop the germination of their seeds.
- Mulches also support stable soil temperatures and moisture retention. Shredded leaves used as an organic mulch for annual plants give the bed a more natural appearance and, as they decompose over time, enrich the soil. Mulches should never be placed on a plant’s stems to avoid potential decay.
- During the growing season, make sure plants are well-watered, especially during dry spells. The growing season requires roughly 1 inch of rain every week for plants. To determine whether you need to add water, use a rain gauge. The optimum irrigation method is a drip or trickling system that releases water at low pressure directly into the soil. To reduce disease issues, water early in the day if you want to use overhead sprinklers so the foliage has time to dry before dusk. Maintain a moist but not saturated soil.
- Some protection from strong winds and intense sunlight may be required until plants grow established. Additionally essential is good airflow.
- A mild fertilizer can be administered after new growth starts to show. To prevent burn damage, keep granular fertilizers away from the plant’s top and leaves. Use moderate amounts of a slow-release fertilizer because greater amounts could promote root rots.
- Unless you are growing them purely for cut flowers and want long stems, pinch young plants to induce branching.
- To prolong plant flowering till fall, remove spent flower heads. Cutting zinnias fosters the emergence of fresh blooms and they make excellent cut flowers.
- Observe for illnesses and pests. For advice on pest management measures that are suitable for your area, contact your cooperative extension service.
- In order to prevent disease problems the next year, remove plants that have been killed by frost in the fall.
Growing Tips
- Zinnias can be arranged in tiny clusters alongside perennials or in mixed plantings with other summer annuals. They thrive in cottage and kid-friendly gardens, and cutting gardens frequently cultivate them.
- For containers, shorter zinnia cultivars are best. Be careful not to crowd them because the plants may grow taller and the blossoms may be much less than they should be. Never use garden soil instead of commercial potting mix, and make sure the containers have enough drainage. Plants growing in containers will need more water and fertilizer; keep an eye out for wilting or nutrient deficiencies.
- For cut flowers, trim stems before the blossom opens.
- Hummingbirds, butterflies, and beneficial insects are drawn to zinnias.
Common Disease Problems
Alternaria Leaf Spot: On the upper surface of the leaves and along the midrib, small, rounded, reddish-brown dots with white to gray centers appear. The lesions could surround the stems and result in wilt. Warm, rainy, or extremely humid conditions makes this sickness worse. Avoid getting water on the foliage, advises Burpee. Avoid working with moist plants and remove any contaminated plant components. Make sure there is lots of air movement. For advice on fungicides, get in touch with local cooperative extension service.
Aster Yellows: Plants grow excessively, become stunted, and develop witch’s brooms. Their petals also turn green and become malformed. Leafhoppers propagate this virus-like ailment. Burpee advises removing and destroying diseased plants. Eliminate leafhoppers. Eliminate any weeds in the area that the illness can also live on.
Bacterial Leaf Spot: The earliest symptoms are small, translucent spots with a wide, yellowish edge. Over time, these spots gradually get larger and develop an angular or irregularly circular shape with a reddish center. It flourishes in cooler climates. Flower heads may be impacted by the disease and become deformed. Burpee advises getting rid of diseased plants. Crop rotation should involve diverse family plants. Avoid watering from above. When plants are damp, stay away from them.
Botrytis: This fungus turns flowers, leaves, stalks, and buds a greyish color. It thrives in chilly, rainy weather. Burpee advises removing the damaged plant sections, avoiding watering at night, and not watering directly on the plant. Make sure plants receive adequate airflow. For advice on fungicides, get in touch with local cooperative extension service.
When the weather is humid, a fungus illness known as powdery mildew develops on the tops of the leaves. The surface of the leaves seems to be white or grayish, and they may curl. Burpee advises giving the plants adequate air circulation through optimum spacing and pruning in order to prevent powdery mildew. For advice on fungicides, get in touch with local cooperative extension service.
Common Pest and Cultural Problems
Aphids: These disease-transmitting sucking insects that feed on the undersides of leaves might be green, red, black, or peach in appearance. On the foliage, they deposit a sticky substance that draws ants. Burpee advises attracting or introducing aphid-eating predators like lady beetles and wasps into your garden. You can also use an insecticidal soap or a powerful spray to wash them away.
Leafhoppers: These insects damage leaves and retard growth. Moreover, they spread sickness. Burpee advises clearing up plant detritus. Use soaps with insecticides. For additional advice on insecticides, contact local cooperative extension service.
Burpee advises hand-picking Japanese beetles in the morning into a pail of soapy water.
Compared to what is typical for the variety, plants are shorter, and blossoms are much smaller: Overcrowding can cause zinnias to become stunted and produce smaller flowers. Always adhere to the spacing guidelines for each variety.
Spider mites: These minuscule insects, which resemble spiders, are approximately the size of a peppercorn. They can be yellow, brown, black, red, or black. They ingest plant liquids, sucking out chlorophyll and injecting poisons that leave the foliage with white spots. On the plant, webbing is frequently seen. They cause the leaf to stipple, dry, and become yellow. They proliferate swiftly and do best in dry environments. Burpee’s Advice Every other day, a strong spray can help control spider mites. Try using insecticidal soap or hot pepper wax. For advice on miticides, contact your local Cooperative Extension Service.