Zinnias are the star of the summer flower garden, loved by novice and expert gardeners. They bloom effortlessly from summer to frost and the more you cut, the more they branch and bloom. If you were wondering how to grow zinnias from seed, youve come to the right place!.
Zinnias are native to Mexico and as a frost-sensitive annual appreciate warm weather. Zinnias bloom heaviest when daylight is less than 12 hours.
When to sow outside: RECOMMENDED. 1 to 2 weeks after your average last frost date. The ideal soil temperature for zinnia seed germination is 70°–80°F.
When to start inside: 4 to 6 weeks before your average last frost date. Transplant outdoors after last frost. Zinnias do not benefit from being planted early; wait for warmer weather.
Use a lightweight seed starting mix/media (sterile, and lighter than potting mix), and sow seeds 1/4″ deep. Plant two seeds in each pot. Once the leaves appear, thin the plants down to the strongest one (use scissors to cut off any extra plants at the soil level). The strongest plant may not be the tallest; look for thick, strong stems and deep color, too. By thinning early, you minimize the negative impact of crowding, like stretching for light. If the seed starting mix you use doesn’t have nutrients in it, feed your seedlings regularly with a liquid fertilizer that has equal amounts of nitrogen, phosphorus, and potassium. It is better to use a weak fertilizer solution more frequently rather than to over-fertilize. Read about more indoor sowing tips.
Nearly any clean container with drainage holes will work. Often zinnias are started in 4- or 6-celled pots, and our 1½” biodegradable pots also work well. Up-pot zinnias into a larger container before they become rootbound, being careful not to disturb roots.
Harden-off seedlings for 7 to 10 days prior to transplanting. Transplant seedlings after the threat of frost has past, as zinnias are frost sensitive. It is best to transplant on a cloudy day or in the evening to reduce transplant stress.
If you want to grow a certain type of plant, space your seeds 8 to 12 inches apart and ¼ inch deep.
Zinnias should always be slightly damp but not soggy. Once plants are established, let the top inch of soil dry out between waterings. Water the soil, avoiding the foliage to help prevent fungal disease. Zinnias can stay healthy and weed-free if you mulch around them. This will also keep the soil moist all season.
Zinnia seedlings should be cut back to just above a set of leaves when they have four sets of leaves. This will help them grow shoots. Zinnias often stay in bloom because deadheading stops them from making seeds, which makes them want to start the bloom cycle all over again.
Zinnias are a popular annual flower that can brighten up any garden with their bright, cheery blooms. Many gardeners start zinnias from seed indoors and transplant them outside after the last frost. But when is the right time to transplant zinnia seedlings? How big should they be before putting them in the ground? In this article, we’ll discuss the ideal size for zinnia transplants and provide tips for ensuring successful transplanting.
When to Transplant Zinnia Seedlings
Zinnias are native to Mexico and prefer warm conditions. They should not be transplanted outdoors until after the last frost date in your area, when soil temperatures have warmed to at least 70°F. Transplanting zinnia seedlings while it’s still cold will stunt their growth.
Most sources recommend starting zinnia seeds indoors 4-6 weeks before your last expected frost. This gives enough time for the seedlings to develop before moving them outside. Some gardeners wait and start seeds only 2-3 weeks prior if they want smaller transplants.
How Big Should Zinnia Seedlings Be?
When transplanting zinnias, the general rule is to move them outside when they have developed their second set of true leaves. This usually occurs 3-4 weeks after germination. The seedlings should be about 2-4 inches tall at this point.
Some signs that zinnia seedlings are ready for transplanting:
-
Have 2-4 sets of true leaves
-
Are 2-4 inches tall
-
Roots are beginning to show through the bottom of containers
-
Appear healthy, stocky and vigorous
You don’t want to transplant zinnias too early when they are still tiny and delicate. But also avoid letting them get too large and rootbound in their starter containers.
Problems with Transplanting Too Early
Moving seedlings outside before they are the proper size makes them more prone to damage from wind, cold temperatures, and pests. Stunted growth or death of transplants are common issues seen with transplanting too early.
Some specific problems with transplanting zinnia seedlings too small include:
-
Cold injury – Young tender seedlings can’t tolerate cold snaps or frost. Their growth is set back and they suffer dieback.
-
Damping off – Seedlings weakened by cold are more susceptible to fungal diseases like damping off.
-
Damage from wind/rain – Small delicate stems easily snap or get battered by harsh weather. Hardening off helps but may not be enough protection.
-
Disturbance to roots – When roots aren’t well established yet, they can be damaged during transplanting leading to stunted plants.
-
Poor survival rates – Higher chances of transplants dying from the combined stresses of early transplant and underdeveloped root systems.
Problems with Transplanting Too Late
On the other hand, letting seedlings get too big before transplanting causes a different set of issues. When zinnia seedlings are rootbound or “pot bound” prior to transplanting, it negatively affects their growth and performance.
Problems seen with transplanting overgrown zinnia seedlings:
-
Permanent stunting – Rootbound plants often fail to thrive and never reach their full potential size.
-
Root circling – Roots that have started circling the container don’t grow properly once planted in the ground.
-
Poor establishment – Seedlings struggle to adjust from their confined starter pots and are slower to establish themselves.
-
Delayed flowering – Plants put energy into untangling roots instead of flowering, pushing back bloom time.
-
Disease susceptibility – Weakened, stressed transplants are more prone to problems like damping off and mildews.
Caring for Seedlings Prior to Transplanting
Proper care when starting zinnias from seed will ensure they reach the ideal size for transplanting on schedule. Here are some tips:
-
Use small individual containers like cell packs instead of large shared pots. This prevents roots from getting overcrowded.
-
Allow at least 2 inches between seedlings to reduce humidity and disease.
-
Water carefully to keep soil consistently moist but not soggy.
-
Give seedlings plenty of bright light from fluorescent grow lights or a sunny window.
-
Begin fertilizing once true leaves appear using a diluted liquid fertilizer.
-
Monitor for pests like fungus gnats, aphids, and thrips which can weaken seedlings.
-
As they grow, gradually expose seedlings to outdoor conditions by hardening off.
Following these simple practices will result in stocky, healthy zinnia seedlings that are ready to transplant on time.
Hardening Off Zinnia Seedlings
An important step when growing transplants is gradually hardening them off for 7-10 days before transplanting. This transition toughens up the seedlings and prevents transplant shock.
To harden off zinnia seedlings:
-
Move them outdoors to a sheltered spot during the day. Bring back inside at night.
-
Slowly increase the amount of time they are left outside over a week.
-
Check plants frequently for any signs of stress like wilting.
-
Allow them to experience light rain and wind. But provide cover if harsh weather occurs.
-
Reduce watering slightly to help seedlings adjust.
-
Transplant on an overcast day or later in the evening to avoid hot sun.
Hardening off ensures transplants establish an
Your cart is empty
Log in to check out faster.
The world needs more flowers, and this collection gives you plenty to…
- Home
- Vegetables
- Flowers
- Herbs
- Organic
- Garden Products
- Specialty Products
- Articles & Blogs
Search
Zinnias are the star of the summer flower garden, loved by novice and expert gardeners. They bloom effortlessly from summer to frost and the more you cut, the more they branch and bloom. If you were wondering how to grow zinnias from seed, youve come to the right place!.
Zinnias are native to Mexico and as a frost-sensitive annual appreciate warm weather. Zinnias bloom heaviest when daylight is less than 12 hours.
When to sow outside: RECOMMENDED. 1 to 2 weeks after your average last frost date. The ideal soil temperature for zinnia seed germination is 70°–80°F.
When to start inside: 4 to 6 weeks before your average last frost date. Transplant outdoors after last frost. Zinnias do not benefit from being planted early; wait for warmer weather.
Use a lightweight seed starting mix/media (sterile, and lighter than potting mix), and sow seeds 1/4″ deep. Plant two seeds in each pot. Once the leaves appear, thin the plants down to the strongest one (use scissors to cut off any extra plants at the soil level). The strongest plant may not be the tallest; look for thick, strong stems and deep color, too. By thinning early, you minimize the negative impact of crowding, like stretching for light. If the seed starting mix you use doesn’t have nutrients in it, feed your seedlings regularly with a liquid fertilizer that has equal amounts of nitrogen, phosphorus, and potassium. It is better to use a weak fertilizer solution more frequently rather than to over-fertilize. Read about more indoor sowing tips.
Nearly any clean container with drainage holes will work. Often zinnias are started in 4- or 6-celled pots, and our 1½” biodegradable pots also work well. Up-pot zinnias into a larger container before they become rootbound, being careful not to disturb roots.
When 2″ tall, thin to 1 every 12″
Harden-off seedlings for 7 to 10 days prior to transplanting. Transplant seedlings after the threat of frost has past, as zinnias are frost sensitive. It is best to transplant on a cloudy day or in the evening to reduce transplant stress.
If you want to grow a certain type of plant, space your seeds 8 to 12 inches apart and ¼ inch deep.
Zinnias thrive in fertile, well-drained soil.
Zinnias should always be slightly damp but not soggy. Once plants are established, let the top inch of soil dry out between waterings. Water the soil, avoiding the foliage to help prevent fungal disease. Zinnias can stay healthy and weed-free if you mulch around them. This will also keep the soil moist all season.
Choose an area with full sun (6 or more hours per day).
If soil is deficient, fertilize with a slow-release or liquid, phosphorous-rich fertilizer.
Zinnia seedlings should be cut back to just above a set of leaves when they have four sets of leaves. This will help them grow shoots. Zinnias often stay in bloom because deadheading stops them from making seeds, which makes them want to start the bloom cycle all over again.
For longest vase life, harvest before the small yellow flowers emerge from between petals.
Common Pests and Diseases
Powdery Mildew looks like a white powder on leaves and thrives in humid weather with cool nights. Keep the leaves dry and only water your plants in the morning and during the day to lower their risk of getting this disease. Proper spacing of plants will provide good air circulation, too. Do not compost diseased plants; spores may over-winter and re-infect crops the following season.
How to Transplant Zinnia seedlings
How do you transplant Zinnia plants?
Dig a hole in the soil that is 1 inch wider than the current root ball size of the zinnia seedling. My pot contains 2 zinnia plants which I will be transplanting into the same hole. Make sure the hole is just deep enough so the top of the soil is the same level as the plant was in the pot.
How do you plant Zinnia seeds?
To plant Zinnia seeds, sow them about ¼ inch deep and lightly water after planting. After about a week, you’ll see seedlings emerge from the soil. Plant the seeds 6 inches apart in the row and two feet apart between the rows. Prepare the garden bed by cultivating and loosening the soil.
When should Zinnia seeds be transplanted?
Consider the following factors when determining the right time for transplanting: Wait until the zinnia seedlings have developed a strong root system and multiple sets of true leaves before transplanting. This typically occurs when the seedlings are around 4 to 6 inches tall.
How long does it take for Zinnia seeds to grow?
Zinnia seeds take 4 to 7 days to germinate and appear as seedlings. However, it will be several weeks to a couple months before blooms appear, depending on the planting site and climate. When seedlings reach three inches tall, thin them so that they’re 6 to 18 inches apart to maximize air circulation.
- Can You Safely Eat a Potato Affected by Blight?A Complete Guide - September 14, 2024
- Are Tomatoes With Green Insides Safe to Eat? - September 14, 2024
- A Visual Guide to Spinach Plants - September 13, 2024