Since tomato plants are so easy to grow from seeds, they are really a favorite food for vegetable gardeners. Seeds for popular varieties can be found at any major seed distributor. Learning about tomato germination and planting is important since gardening with tomatoes is so rewarding!.
Gardening friends get together to discuss tomato plant cultivation just as spring arrives. To make it easy to grow tomatoes indoors, they use grow tents, greenhouses, or hydroponic systems that have the right amount of light and temperature. Starting tomato seeds will give you ample experience in growing food. And the flavor difference between a grocery store tomato and one grown in the garden cannot be denied.
Anyone who wants to learn more about the tomato plant life cycle should grow tomato plants from seeds. But what is going on during the germination process of a tomato seed? Let’s look at the plants that are involved in growing tomatoes from seeds.
Before a tomato seed becomes a seedling, it has to go through an enzymatic process called germination. Here is a basic overview of that process.
A seed starts out as an embryo, which is a dormant cell. An embryo is surrounded by a seed coat and an endosperm, which protect it. In the Solanoideae sub-group, which hosts tomatoes and peppers, the seed coat is relatively thin. It is broken through exposure to the right temperature and moisture.
The endosperm provides the seed embryo with starches that aid in germination. The embryonic root is covered by a cap. When heat and water break down the seed coat, the root and cotyledon come out of the seed. Tomato seedlings’ cotyledon rises to get nutrients from the air above them through sunlight, and the root embryo dips below to get nutrients from the compost. Tomato seeds contain one cotyledon, which becomes the first leaves of tomato seedlings. The cotyledon absorbs nutrients and ultraviolet light to feed young plants.
If you’ve ever grown tomatoes from seed, you know how exciting it is to see those first sprouts emerge from the soil Tomato seeds usually germinate within 5-10 days after planting Once they sprout, the tiny seedlings undergo rapid growth and changing before becoming full-sized tomato plants. In this article, we’ll take a close look at the sprouting and early growth stages of a tomato plant so you know exactly what to expect and can provide the best care during this critical time.
Germination Stage (Days 1-10)
Germination is when the seed sprouts and the first root emerges. Here’s a step-by-step look at what happens:
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Day 1: The seed absorbs water and swells up. This kickstarts the germination process.
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Day 2-3 The radical or embryonic root emerges from the seed coat and grows downwards
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Day 4-5: The hypocotyl, or new stem, elongates and pushes the cotyledons (seed leaves) up through the soil.
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Day 6-10: The cotyledons open and turn green. These leaves don’t look like normal tomato leaves. They are thick and oval or round in shape. The young root continues growing down while the hypocotyl keeps arching upward bringing the cotyledons completely clear of the soil surface.
![Sprouted tomato seed with thick round cotyledons][]
Sprouted tomato seed with thick round cotyledons. Source: The Old Farmer’s Almanac
Pay close attention because the cotyledons emerge and open quickly. If you blink, you might miss this first stage!
Early Seedling Stage (Days 10-20)
After the cotyledons open, the plant enters the seedling stage. Here’s what to look for:
- Days 10-13: The cotyledons continue expanding and the first true leaves appear. These leaves look like normal serrated tomato leaves but they are quite small at first.
- Days 13-15: More true leaves emerge. There are now 4 leaves total – 2 cotyledons and 2 true leaves. The stem and roots begin to turn purple or green.
- Days 15-20: Additional true leaves develop. There are 6 leaves now. The seedling grows taller, the stem and roots elongate, and the root system expands downwards.
So during the second stage, you’ll notice the tomato seedling getting larger and more complex. The cotyledons provide nutrients while the true leaves start photosynthesis. Make sure the seedlings get plenty of light at this point!![Tomato seedling with 2 cotyledons and 2 small true leaves][]
Tomato seedling with 2 cotyledons and 2 small true leaves. Source: The Old Farmer’s Almanac
Preparing for Transplanting (Days 20-30)
In the third stage, the seedling focuses on root and foliage growth in preparation for transplanting:
- Days 20-25: The leaves and stem continue expanding upward. More true leaves emerge until there are up to 8 leaves total.
- Days 25-30: The root system spreads out filling up the container. Flower buds may begin forming. The plant looks like a miniature tomato plant now.
When the seedling fills its container with roots and has several true leaves, it’s ready to be transplanted into the garden or a larger pot. This typically occurs around 4 weeks after sowing the seeds.![Bushy tomato seedling ready for transplanting][]
Bushy tomato seedling ready for transplanting. Source: The Old Farmer’s Almanac
Providing Proper Care
As you monitor your sprouting tomato seeds and growing seedlings, be sure to provide proper care:
- Moisture: Keep the soil consistently moist but not soaked. Water when the top inch becomes dry.
- Warmth: Maintain temperatures around 70-80°F for optimal germination and growth.
- Light: Give seedlings 14-16 hours under grow lights or in a sunny window.
- Air circulation: Gentle air flow prevents disease. Use a small fan to circulate air.
- Fertilizer: Apply a nitrogen-rich fertilizer once true leaves emerge.
- Thinning: If more than one seed sprouts per cell, snip off the weaker ones with scissors.
With the proper environment and care, your tomato sprouts will thrive right from the start. Pay close attention to their growth stage and changing needs. The healthy seedlings you grow now will translate into a bountiful tomato harvest later!
Common Issues with Tomato Sprouts
While most tomato seeds sprout without issue, you may encounter problems like:
- Poor germination: This could be due to old seeds, incorrect soil temperature or moisture levels, or planting too deep.
- Leggy seedlings: If stems and leaves stretch and flop over, the seedling isn’t getting enough sunlight.
- Discoloration: Purpling of the stems and leaves may indicate cold temperatures or phosphorus deficiency.
- Slow growth: Inadequate light, improper hardening off, or overwatering can stunt seedling growth.
- Damping off: Fungal disease causes seeds and seedlings to rot at the soil line. Improve air circulation to prevent damping off.
Catch problems early and make adjustments to get your sprouts thriving again!
Frequently Asked Questions
Here are answers to some common questions about tomato sprouts:
How long does it take for tomato sprouts to emerge?
Tomato seeds usually germinate in 5-10 days after planting. The timeframe depends on soil temperature, planting depth, and seed age.
What do tomato sprouts look like?
When seeds first sprout, you’ll see two green, oval cotyledon leaves rising up out of the soil. The stem and roots will be white.
How many leaves do tomato sprouts have?
Tomato sprouts start with just two cotyledon leaves. Within two weeks, they develop 2-4 true leaves for 4-6 leaves total. More true leaves continue emerging after that.
Can you transplant tomato sprouts?
Tomato sprouts can be transplanted once the root system fills the container and they have at least 2-4 true leaves. This usually occurs 3-4 weeks after germination.
Why are my tomato sprouts turning purple?
Purpling of the stems and leaves indicates cool temperatures below 55°F. This isn’t harmful but seedlings grow best with warmer 70-80°F temperatures.
Conclusion
Paying close attention to your tomato plants as soon as they sprout is crucial. Look for the cotyledons to emerge first, followed by the growth of true leaves and branching of the main root and stem. Providing proper moisture, warmth, and light ensures your sprouts transition smoothly into healthy seedlings ready for transplanting. With a little care, your tiny sprouts will soon become mighty tomato plants!
How to Germinate Tomato Seeds
There is no one particular way to germinate tomatoes. They can thrive outdoors, indoors, or even in a hydroponic system. Starting tomato seeds is a cinch!.
Start tomatoes in trays with potting soil. Seed starter pellets can also be used, but we highly recommend Epic 6-Cell Seed Starting Trays. Place on a heating mat. Plant the seeds about ⅛ inch deep and wrap the tray or starter pot in plastic wrap to keep the heat and water in. Keep the mat heated within the range of 60 to 70 Fahrenheit. Seeds should germinate within one to one and a half weeks. If it takes a long time for the seeds to sprout, it’s likely because there isn’t enough heat. Simply increase the temperature on your heating mat if you notice this.
In the northern hemisphere, put tomato plants in a sunny south-facing window. In the southern hemisphere, put them in a sunny north-facing window. Try not to expose your seedling containers to too many hours of sunlight. For seedlings, a few hours a day of temperatures between 50 and 70 degrees Fahrenheit are best. Too much heat from the sun will burn plants. Note that sprouting in a warm windowsill could produce leggy seedlings. If possible, use a grow light instead.
Grow tents are a great way to control the climate around your seedlings and ensure higher germination rates. Begin by starting seeds in potting soil in containers, and place them in your tent. For plants that don’t need soil, you can use coconut coir or a mix of vermiculite, perlite, and sand. Whatever mix you use, ensure it’s suited to tomato seedlings. Adjust the temperature and the humidity in your tent as needed. Then plant them in a larger pot when the cotyledons fall off. One sign that the humidity is too high might be soil that looks a little moldy.
A tomato plant can also be grown in a hydroponic system. This way, you’ll get a good healthy yield from each plant, conserve water, and carefully control the climate. But your whole plan could fail if the pH of your nutrient mix is off by even a little. For hydroponics, plant in a soilless mix. Then you should put seedlings in your hydroponic system in a solution of nutrients that has a pH of about 4. 5.
If you live in a warm place with a long growing season, you can plant seeds in the ground of your garden when the weather is right. This is the riskiest method of starting seeds as they are fully exposed to the elements. Animals, insects, and heat can damage seeds quickly. Gardeners who start seeds outdoors know to observe carefully and use caution.
Seedlings that will be planted outdoors must be hardened off in their pots for a couple of weeks. To get your tomato seedlings ready for the garden, put them somewhere partly sunny for a couple of weeks. Check on them often. Then transplant them to a container or in the ground.