Tomatoes are one of the most popular plants to grow in the garden, and for a good reason. They’re not only delicious but also very easy to care for. As long as you provide them with a sunny location and keep their soil moist, you’ll be rewarded with a bountiful harvest.
Planting tomatoes from seed is one of the best ways to grow your produce. It’s cheap, easy, and allows you to plant whatever variety of tomato you want. Depending on what works best for your timeline and climate zone, you can even start your seeds indoors or outdoors.
The key to successfully starting tomatoes from seed is finding the right seed-starting mix. Although there are several types of potting soil, only one has the right texture, nutrients, and pH level that tomatoes need to germinate and thrive. This article will discuss the best seed starting mix for tomatoes.
If you are a gardener, or even if you are curious about gardening, you may have heard the term “seed starting mix” or “seed starting soil.” But what is the seed starting mix, and why do you need it?
What is Seed Starting Mix?
Seed starting mix is a lightweight mixture of soil and organic matter that is sterilized and free of pathogens. It typically contains peat moss, perlite, and vermiculite but may also include sand, coarse coconut coir, and other materials.
Why Do You Need Seed Starting Mix?
Seed starting mix can be used for many purposes, including growing seeds indoors and transplanting seedlings into other pots or containers. The main purpose of using seed starting mix is to ensure proper drainage and aeration for the plant. Soil from outdoors tends to be heavy and can get compacted easily, resulting in poor drainage. In addition, soil from outdoors will often contain pathogens that can harm your plants’ growth. Lastly, soil from the outdoors is usually too slow draining for most plants, especially those that require well-drained soil, such as cacti and succulents.
What are the best ingredients for starting tomato seeds?
Sphagnum peat moss
Sphagnum moss is a great medium for starting or propagating tomato seeds. It’s available online and in garden centers and some specialty stores. It is available in peat moss, sphagnum liquid, sphagnum pellets, etc.
Peat moss has water-retaining properties, which are ideal for starting seedlings because they help you to keep the seedling moist while they’re germinating.
It can be used as a growth chamber under fluorescent lighting to get your seedlings ready for transplanting into pots.
It’s also a good option for starting seeds outdoors if you have a warm, frost-free winter climate with no danger of frosts that can kill young seedlings.
Sphagnum peat moss is fairly easy to work with and doesn’t need a lot of preparation. The trick is to make sure it’s kept moist and never dried out during growing. You want the peat to stay damp throughout the growing season, so use it only when the temperature outside goes below 45 degrees Fahrenheit (and even then, it’s best to check the temperature inside your greenhouse before placing your seedlings in a pot).
This is the white stuff that looks like popcorn pieces. It’s hardened molten glass (it’s very safe). You can find it in any garden center or larger home improvement store, usually sold by cubic foot. Perlite is used in potting mixes to help them drain faster and retain moisture better. A common ratio is 1/3 perlite and 2/3 peat moss to make up the bulk of your mix.
Perlite is the best choice for seed starting media because it meets all of the criteria of a good germination medium:
- Lightweight (makes it easy to handle)
- High drainage abilities
- Easy to control moisture retention
- pH between 6 and 7 (neutral or slightly acidic)
Vermiculite is a soil amendment used to improve drainage and aeration in the garden. It’s especially useful in sandy soils, which tend to drain quickly and lose moisture.
The most common reason for using vermiculite is that it is sterile. Most people try to start their seeds in a sterile environment. This reduces the chances of introducing a fungus or bacteria into your seed starting mix, which can wipe out all of your seeds before they even sprout.
Vermiculite is also very light and porous. This allows it to retain a lot of water, which helps keep your seeds moist while they are germinating. It also helps it drain well so that your seeds do not get too wet.
Vermiculite is easy to use and does not need preparation before planting your seeds. Unlike peat moss, which needs to be hydrated before use, vermiculite is ready to go right out of the bag.
Lime is a calcium-rich rock that is available in powdered form. Adding lime to seeds or seed-starting mix helps prevent blossom end rot, which can be a problem on tomato plants if the soil is acidic (low pH).
Blossom end rot is a physiological disorder of tomatoes, peppers, and eggplants. The bottom of the tomato or pepper turns black and rots, leaving an ugly scar. Blossom end rot does not attack the plant’s roots, stem, or leaves. It is caused by a low level of calcium in the fruit, which can happen when:
- The soil pH is below 6.0 (too acidic)
- The soil lacks enough calcium.
- The soil lacks enough nitrogen (fruit growth slows if there’s not enough nitrogen in the soil).
- There’s too much water stress on the plant (consistently wet or dry soil).
Lime helps raise pH levels in acidic soils so plants can absorb calcium. It also increases the amount of calcium in sandy soils, where it washes out quickly. You can use dolomitic limestone or hydrated lime to raise pH and add available calcium to your garden soil.
Let’s review some of the best seed starting mixes for tomatoes you can easily buy online. They include:
Sun Grow Black Gold Seed Starting Mix
What makes Black Gold special? It’s a blend of organic materials, including peat moss and earthworm castings, that will hold moisture and nutrients. And it contains mycorrhizae, beneficial fungi that help plants absorb water and nutrients from the soil.
This product is OMRI-listed for organic gardening, which means it’s approved for use in organic production by the Organic Materials Review Institute.
- Fibrous, peat moss-based compost.
- Moisture-retaining properties.
- Good drainage properties.
- Completely sterile growing medium.
- It contains no weed seeds or pathogens, with no seedling disease or insect damage.
- It’s pH balanced.
- Promotes healthy root growth and strong seedling development.
Jiffy Natural and Organic Seed Starting Mix
Jiffy Natural Seed Starting Mix is a convenient, nutrient-rich, and uniform soil-free growing medium that supports seed germination and early plant development. Jiffy is a special combination of organic materials that provides all the necessary elements for healthy plant growth.**
Jiffy is a high-quality mix that contains no added ingredients or artificial additives. It’s moisture-proof and will not dry out during storage. It contains the perfect amount of nutrients for each stage of plant growth and will not cause any disease problems in your seeds.
Here are the features that make Jiffy Natural and Organic Seed Starting Mix stand out:
No pesticides or herbicides: Many commercial potting mixes contain neonicotinoids, a class of pesticide that can be deadly to bees. That’s not something you want in the soil growing seedlings in. And some mixes may have been treated with other insecticides or fungicides that could harm young plants. Jiffy Natural and Organic Seed Starting Mix has no pesticides or herbicides.
Complete nutrient package: Even if you know what kind of fertilizer your seedlings need, it’s usually difficult to amend commercial potting mixes to provide it. The fertilizer blend in Jiffy Natural and Organic Seed Starting Mix is perfectly balanced for seedlings — they just need water.
Retains moisture: When starting seeds, they need to stay moist without getting waterlogged. It’s easy to overwater when you want to make sure young plants get enough water, but too much can cause them to rot before they even germinate. Jiffy Natural and Organic Seed Starting Mix retains moisture so well that it only needs watering once a day (or less).
Miracle-Gro Seed Starting Potting Mix
Grow new plants easily with Miracle-Gro Seed Starting Potting Mix. It has nutrients to feed seedlings and young plants to help them grow big and strong. This soil contains a wetting agent that improves the absorption of water and nutrients. Miracle-Gro Seed Starting Potting Mix is a good solution for starting seeds, cuttings, and rooting houseplants. This potting mix contains horticultural-grade peat moss, perlite, and limestone, allowing for ideal air porosity and water drainage. The formula also includes fertilizer to feed your plants for up to 3 months.
- Ideal for starting seeds and rooting cuttings.
- It contains sphagnum peat moss for optimum aeration and moisture retention.
- It is enriched with Miracle-Gro Plant Food for stronger root growth.
- Formula feeds seedlings for up to 6 weeks.
- It helps seeds and cuttings get a healthy start.
- Lightweight mix.
- It is specially formulated with Miracle-Gro Plant Food.
- It contains sphagnum peat moss, composted forest products, and perlite.
Burpee Natural and Organic Seed Starting Mix
Burpee® Organic Seed Starting Mix is a finely textured, high porosity mix for ideal seed starting. This mix is ideal for all seeds, contains coconut coir for moisture control, and is enriched with a water-soluble fertilizer. For best results, remove seedlings when they are the correct size to be transplanted into the garden or containers.
- Organic seed starting mix.
- Ideal for all types of seeds.
- It contains coconut coir for moisture control.
- Enriched with a water-soluble fertilizer.
Espoma Organic Seed Starter Potting Mix
Organic Seed Starter is a premium, all-natural, organic mix that promotes strong root development while protecting your seeds. It contains mycorrhizae, a beneficial soil microorganism that enhances nutrient and moisture uptake through the roots. Specially formulated to nourish your seedlings as they grow and start right!
- Organic seed starting mix with mycorrhizae.
- All-natural and organic seed starting mix.
- It contains mycorrhizae to promote root health.
- Feeds plants for up to 6 months.
- Improves nutrient uptake while reducing transplant shock.
Black Gold Seedling Mix
The Black Gold Seedling Mix is high quality and all-natural product. It will come in handy for any seed starting you may want to do. It is also great for indoor and outdoor growing pots. You can use this product to start just about any seed you can think of, including vegetables or even herbs.
- Each bag holds 8 quarts of soil
- Seedling mix is ideal for starting seeds and cuttings
- Contains a blend of sphagnum peat moss, reed sedge peat, and perlite
- Formulated to provide good aeration and drainage while holding moisture.
- Features a light texture that is easy to handle.
ProMix Premium Organic Seed Starting Mix
This 100% Organic Seeds Starter Mix is ideal for starting seeds and rooting cuttings. It contains Canadian sphagnum peat moss, perlite, composted bark fines, soft rock phosphate, greensand, kelp meal, and dolomitic lime. OMRI is listed for organic gardening.
- Perfect for starting seeds and cuttings.
- It contains the ideal balance of organic matter, nutrients, and trace elements for healthy seed germination and growth.
- Professional growers prefer them.
- It can be used with potting soil to increase the organic content.
Which products can you mix with your current soil to make the best tomato seed starting mix?
Miracle-Gro Perlite can help ensure a successful harvest when you’re growing indoors. It helps with aeration, drainage, and water retention. It also contains nutrients that feed your plants.
It helps aerate soil blends, so roots have plenty of room to grow.
It contains essential plant nutrients that feed your plants for up to 3 months.
Encourages strong root development for better growth.
For indoor and outdoor container plants.
Sphagnum Peat Moss
Greensmix Sphagnum Peat Moss
Greensmix Sphagnum Peat Moss is the best choice for lawn, garden, and house plants. Garden soil needs to be well-drained; this peat moss adds organic matter to aid in water retention. Green Sphagnum Peat Moss will also help balance pH levels by increasing acidity and aerating soil. Perfectly sized for all types of gardening projects, it is great for seed starting and potting mix use. It can be used for various growing conditions, including raised beds and container gardens.
- All-purpose soil amendment
- Adds body to soil mixes
- Improves soil structure
- Increases aeration
- Reduces water loss
Char Coir 100% RHP Certified Coco Coir
This RHP-certified coco coir (coconut fiber) has a low salt content and a high air-filled porosity. Use it as a soil conditioner or an amendment to your existing soil. It can be used by itself, although you may want to add some nutrients to the mix. This product comprises fully matured coconut husks and contains no fillers. It is free of any soil or foreign matter.
- 100% RHP Certified Coco Coir.
- 100% natural coconut coir is a renewable resource.
- Excellent for seed starting, hydroponic growing, and indoor gardening.
- Great water retention properties.
- Ideal for soil amendment or use in potting mixes.
Harris Premium Horticultural Vermiculite
Harris’s vermiculite is a lightweight and sterile soil additive that improves aeration and drainage. It is 100-percent organic and safe for all plants, making it ideal for indoor use. This product can be mixed with other growing media or used alone.
- Pure and clean horticultural vermiculite with no additives.
- No chemical coatings or treatments.
- Lightweight, sterile, odorless, and non-flammable.
- Aids in seed germination and the development of strong roots.
- It gives the growing medium good water holding capacity.
- Allows the soil to breathe and holds nutrients for better plant growth.
Tomatoes are one of the most popular and rewarding garden crops, but most varieties won’t germinate if the soil is too cold. Therefore, growing tomatoes from seed require a little more preparation than some crops.
Here’s what you’ll need:
- Seed starting mix
- Seed starting trays
- Heat mat
- Watering can with a fine rose
You can use a heat mat and seed starting trays to save space. This is essential gear for tomato seedlings. Here’s why:
Seed Starting Trays
For propagating seeds, use a good-quality seed-starting tray with cells for each plant and holes for good drainage. These trays are reusable, but if you have an old one with a cracked bottom, I wouldn’t recommend using it as the soil can seep out the bottom. Or maybe you have an old one where the plastic turns yellow and brittle – throw it away and get a new one!
A heat mat is important to start your seeds because they need to be kept warm during the germination process. You want them to be kept at around 70 degrees F or 21 degrees C. You can control how warm they are by simply adjusting the time you leave them on. For example, if you put your trays on your kitchen countertop or other areas that don’t stay at a constant temperature, consider using a heat mat to keep them nice and warm during the day and then turn it off at night when you don’t need it.
In the end, the best seed starting mix for tomatoes does come down to your preferences and goals. If you don’t mind buying a bag, Miracle-Gro potting mix is a good choice, but if you want to save money home, made mixes are a viable alternative that can save you plenty of cash in the long run.
Whichever type of mix you choose, the most important thing is to ensure that it’s high quality and free of contaminants. Your goal should be to provide your seedlings with everything they need to grow strong and healthy, so don’t skimp on quality—whatever you use as a growing medium will greatly impact your results!
Here are all the products mentioned in this article for starting tomatoes from seed, sorted by price:
For further information, here is a great video on growing tomatoes from seed using seed starting mix: