Transplanting & pricking out tomato seedlings: when, how & what soil
Spring is the perfect time to prick out and transplant tomatoes, before planting them out a few weeks later. Here are some helpful tips on how to go about this, including what soil to use, to give your tomatoes the best chance of success!
Pricking out tomato seedlings
Pricking out tomatoes involves gently separating the newly germinated seedlings and transferring them into their own pots. As tomatoes are hungry plants, they need a nutrient-rich soil after germination to stimulate growth and prevent deficiency symptoms. They also need more space to develop good strong roots. Pricking out seedlings can be tricky, so it takes a bit of time and patience to get it right!
When should tomatoes be pricked out?
Three to ten days after sowing tomato seeds, the first seedlings emerge. These should then be left in their seed tray for some time, allowing the plant to develop its first pair of true leaves, which are typically lobed or serrated. As the young plants begin to grow and the stored nutrients from the seed are depleted, they soon need a fresh supply.
What soil to use for pricking out tomato seedlings
For pricking out tomatoes, a pre-fertilised soil that provides all the essential nutrients is best. On top of that, the soil should be humus-rich, have a loose, permeable structure, and be able to store water well. Our Plantura Organic Tomato & Vegetable Compost combines all these properties while also being eco-friendly, as it does not contain any peat.
- Perfect for tomatoes & other vegetables such as chillies, courgettes & more
- For strong & healthy plant growth as well as an abundant vegetable harvest
- Peat-free & organic soil: CO2-saving composition
How to prick out tomatoes
First, carefully lift the seedlings out of the soil. This is easier with what is called a transplanting dibber, or you could simply use a wooden lolly stick or a spoon. Take care not to damage the leaves or roots of the tomato seedlings. Then place them in a larger pot with a diameter of 8 to 12 centimetres filled with nutrient-rich potting soil. It is important that you pick up the seedlings only by the leaflets and never by the stem. The stem contains tubes which are essential for carrying water and nutrients around the plant, so if these are damaged, your tomato seedlings could end up drying out in their new pot. Plant the seedlings up to the base of the first true leaves, removing the cotyledons (the baby leaves that emerged before the true leaves). Then lightly press down and water the soil. This will flush the water directly to the roots and stimulate growth.
Should the cotyledons be removed when pricking out? Yes, the cotyledons should be snipped off when the tomato seedlings are inserted deep into the soil to prevent the baby leaves rotting on the plant.
Summary: Pricking out tomato seedlings
- About 2 – 3 weeks after sowing the seeds, prick out the seedling as soon as the first true leaves become visible.
- With a transplanting dibber or spoon, lift the young plants out of the soil, only grasping them by the cotyledons.
- Place the tomato plants in pots 8 – 12 centimetres in diameter filled with nutrient-rich soil.
- Plant the seedlings up to the base of the true leaves.
- Fill in the soil, press lightly all around, water well and place pots in a bright, warm location.
Planting out tomatoes
After having been placed in a new pot with nutrient-rich soil, the tomato plants will shoot up in no time. If you plan to grow the plants outside, it is very important to harden off your tomatoes before planting them out. Provided the weather in April and early May is warm enough, you can begin to leave the plants outdoors for a few hours at a time, gradually increasing this day by day. This way, the plants become more robust and are less likely to suffer from transplant shock, as they have already been exposed to the colder temperatures and stronger sunlight outside. Too much sun, however, can be harmful to the sensitive young plants as it can cause sun damage. In this case, the leaves may even appear almost translucent, as they become thinner and lose chlorophyll. To avoid this, be sure to place your young tomatoes in partial shade to begin with. Should the weather suddenly become very humid or there is a sudden temperature drop during this hardening off process, simply bring your plants back indoors until conditions improve.
Tip: Should the leaves of the tomato seedlings turn yellow before planting them out, this may be down to a lack of light or a shortage of nutrients. If lack of light is ruled out by a sunny location however, focus on fertilising your plants. A liquid fertiliser is the best choice here, as it is applied during watering, quickly remedying acute nutrient deficiencies.
When should I transplant tomatoes?
Tomatoes are very sensitive to frost and should therefore not be planted outdoors until mid-May onwards. In a greenhouse or polytunnel, however, this can be done a few weeks earlier as it can hold warmer temperatures.
Planting tomatoes: plant spacing and methods
The right spacing between the tomatoes is essential to keep the plants healthy. We recommend 50 – 80 centimetres between individual plants and 80 – 100 centimetres between rows. However, this varies for different varieties, as wide spreading wild tomatoes need more space than the tall and slender beef tomato. Good spacing allows air-circulation, prevents dampness and reduces the risk of fungal diseases spreading through your crop.
To plant the young tomato, dig a hole as deep as possible in the bed. Alternatively, you can prepare a large pot with a volume of 10 litres, by covering the bottom with a few centimetres of high-quality potting soil. Bear in mind that the soil should meet the same criteria as already used for pricking out. Then, free the plant from its old pot by gently pressing the soil and pulling out the plant. Now place the tomato in the new pot or planting hole. Similar to pricking out, insert the plant deep into the soil so that only about one third of the stalk is above the surface and carefully pinch off any leaves which are below this level. New roots will form underground along the stem, increasing water and nutrient absorption later.
Tomatoes are heavy feeders, which means they require plenty of nutrients. For an optimal supply, mix compost or a natural slow-release fertiliser, such as our Plantura Tomato Food, into the excavated soil. This allows the nutrients to be released gently and slowly over a period of weeks, meaning you only have to fertilise once every three months.
- Perfect for tomatoes, chillies, courgettes, cucumber & more
- For healthy plants & an abundant tomato harvest
- Long-lasting fertiliser that is free from animal products - child & pet friendly
Now you can fill the pot or the planting hole with soil and press it down lightly. All that is left to do now is water your plant well. For particularly tall plants, we recommend staking with a wooden stick or strings attached above for support. Supporting sticks or stakes have to be pretty strong for heavy beef tomatoes. Sturdy bamboo canes, hazel branches or spiral supports made of metal are best suited. To guide the plant upwards, wrap the string around the entire length of the stem, before loosely tying it to a wooden stick. Upright plants make harvesting easier and reduce the risk of the plant or its fruit becoming infected with pathogens through contact with the soil. Take a look at this article for more tips on tying up tomatoes.
Tip: It is also possible to plant tomatoes in a raised bed.
Summary: Planting out tomatoes
- Plant tomatoes in beds or pots outdoors from mid-May onwards, in the greenhouse from the beginning of May.
- Keep a spacing of 50 – 80 cm between plants, 80 – 100 cm between rows.
- Dig a deep hole in the ground so that 2/3 of the plant sits below the soil surface.
- Mix compost or slow-release fertilisers into excavated soil.
- Fill in the planting hole or pot with soil, water well and support tomato plants.