How To Plant Zinnias Indoors

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.

Planting in the Garden:

  • 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.


Is it better to start my zinnias outside or inside? You can either start zinnias inside or outside, in the garden. You can get a head start by beginning them indoors if you have suitable indoor growth conditions, such as plant lights and a heat mat for germination. However, because zinnias are simple to grow from seed and bloom quickly, some gardeners may find that direct sowing is a superior alternative.

Is it possible to cultivate zinnias indoors? Zinnias may not thrive in many homes since they need full sun and high temperatures to develop effectively. In the summer, shorter varieties can be tested in a warm sunroom.

How should I take care of the cut zinnia flowers? When you cut your flowers in the garden, bring a pail of water with you, and as soon as you cut the flowers, immediately submerge them in the water. They will be able to absorb water through the newly sliced stem as a result. More surface area for the water to absorb when cut at an angle. Keep them away from the sun’s rays.

Do my zinnias need to be staked? Staking may be beneficial for taller kinds, especially if they are in a windy environment.

Why do my zinnias have much less flowers than I imagined and are tall and lean? Zinnias will grow tall plants and much smaller flowers if they are planted too near together. Always adhere to the planting instructions’ suggested spacing.

Can zinnia grow inside?

Make sure there is enough room and airflow around your potted zinnias. This aids in preventing the growth of the white powdery mildew that zinnias are prone to.

In the flower garden, zinnias are a well-liked annual. If you plant zinnias in a greenhouse or under fluorescent grow lights, you can grow them indoors. To prevent the pots from tipping over when the top growth’s mass exceeds the sum of the masses of the pot and its soil, pick one of the numerous shorter zinnia kinds. If you take off the wilted flowers, zinnias can stay alive for months indoors.

Get the growth containers ready. Indoor potting soil with fertilizer should be poured into 6- to 8-inch pots to within an inch of the top. To settle the dirt, tap the pots’ bottoms on a solid surface.

  • In the flower garden, zinnias are a well-liked annual.
  • Indoor potting soil with fertilizer should be poured into 6- to 8-inch pots to within an inch of the top.

A large shallow container should be half-filled with water. The shallow container should be filled with the seed-planting pots. Remove from water and let drain when the soil surface in these pots appears damp. To keep the soil moist until the seeds sprout, mist it every day.

Place the pots beneath a light source. As soon as seeds begin to sprout, or after around 10 days, grow lights. As the plants grow, give them a way to be raised so they are always approximately 3 to 4 inches over the tops of the plants. As an alternative, zinnias can be grown in a heated greenhouse.

  • In each pot, plant three to four seeds.
  • Once the seeds have germination, which takes around 10 days, place the containers under fluorescent grow lights.

Thin plants to the strongest seedling in each container once they have developed their third set of leaves.

Water the seedlings when the soil looks dry on top after keeping them generally moist until they are well-established. After watering, don’t let the water that drains out of the pots’ bottoms sit in the pots.

When should I start my indoor zinnia garden?

Zinnias (Zinnia elegans) are flowering annuals that offer summer color to a patio or garden. They have been a mainstay in the home garden for many years. Zinnia blooms can be grown in USDA hardiness zones 3 through 10, although they cannot withstand freezing. Before the final spring frost, plant zinnia seeds indoors to get a head start on your garden. When sown indoors, zinnias are simple to grow and should sprout within a week.

Do zinnias thrive in containers?

Zinnias provide color to any flower garden, are excellent for cutting, are simple to cultivate from seeds, and are a terrific option for container gardening.

Can zinnias be brought indoors during the winter?

Taking cuttings from your existing plants is another approach to overwinter annuals and the only practical method for true annuals. For delicate perennials like coleus and begonia that do not adapt well to transplanting, this may also be the best method.

Take a Cutting

Take 3- to 5-inch cuttings from plants that are actively developing in the middle to end of the summer. (Some plants can still be pruned into mid-fall.) Take the cuttings from non-flowering shoots if at all possible. If you must remove them from flowering shoots, remove any blooms or buds from each cutting by cutting or pinching them off. The cutting will be able to focus its efforts on growing roots as a result.

Root the Cutting

Each cutting should have the lower half of its leaves removed. The bottom third of the stem should then be inserted into a pot of moist potting soil. Although most cuttings will root without it, you can dip the cut end in rooting hormone if you choose.

Gardening Tip

If the cuttings are merely suspended in a glass of water until a strong root system forms, some plants will root rather successfully. Plants that readily take root in this manner include begonia, coleus, and impatiens. However, when roots are grown using this procedure and then moved to potting soil, they occasionally may not adapt well. The preferable technique, in the opinion of many, is to root plants in potting soil from the start.

Cover the Cutting

To keep the plastic off the plant, place a plastic bag over the pot and support it with skewers, twigs, or stakes. Set the pot somewhere where there is a lot of bright indirect light, but preferably not in the sun.

Wait for Roots

Keep an eye on the covered pot. Maintain the potting soil at a light mist but avoid saturation. Open the plastic briefly to let the moisture escape if condensation forms on it. The cuttings should root in three to four weeks. If you pull on the cutting and it resists your pressure, the root system has established. The pot can then be placed in a sunny window or under grow lights after the plastic bag has been removed. To continue developing the rooted cutting, you can transfer it into a bigger pot.

Care for the Plant

As with any indoor plant, care for your overwintering plants. Make sure they receive adequate light, water them in accordance with the needs of their species, and keep a watch out for any insect or disease issues. Typically, they won’t require food throughout the winter. However, if you’d like, you can begin providing them with a liquid meal, like vermicompost tea, in the late winter or early spring.

Move the Plant Back Outdoors

Give your newly rooted plants some time to adjust to outside conditions before relocating them there permanently when it’s time to relocate them back outside. Move the pot outside each day for an increasing number of hours after the threat of frost has passed. Spend at least a week doing this. After that, you have two options: either keep your plants in their outside containers or grow them in your garden.

Gathering seeds from your garden annuals and starting them indoors throughout the winter is another way to “overwinter.” This procedure has varying degrees of success because some hybrid plants do not “come true” when their seeds are sown because their seeds have a different genetic makeup than the parent plant. Other delicate perennials develop so slowly that starting them from collected seeds would not be practical. However, certain popular genuine annuals, like zinnias and snapdragons, are relatively simple to multiply in this manner. Simply keep the small seeds from flower heads that have finished maturing and collect them to plant indoors in potting soil or seed starter soil about two months before the last winter or spring frost. These species grow so quickly that it’s simple to create a nice crop of seedling plants to put outside in the spring.