Tomatoes are a warm and cold-loving crop, so temperature is critical when germinating – keep the temperature at 20°C and above, and you need lots of moisture.
Keep out of the light, wrap them in a clean wet towel and keep them moist for about 12 hours to germinate. Sow seeds for seedlings immediately after germination.
Seedlings take about 5-7 days to emerge when nursery, and it is important to keep the soil moist during this time. Dry soil in the seedbed will dry out the germinated seeds again and cause a lack of seedlings. To save time, you can also cover the seeds with mulch after sowing to keep them moist and warm, and keep a check on the mulch at all times.
Transplant when the seedlings have 3-4 leaves. Apply sufficient fertiliser and transplant the plants 30-50cm apart. Water immediately after planting to allow the soil and roots to fit closely together so that the tomato seedlings can be brought back to life and growth can resume in about 5-6 days.
The seedlings will be alive and growing in about 2 weeks after the seedlings have been given sufficient fertiliser, so it is important to water them thoroughly.
The aim is to quickly promote the growth of thick and strong seedlings. In combination with watering, follow up with a compound fertiliser to promote bud differentiation and strong flower buds.
The second fertiliser waits until about 7-10 days after the first spike of fruit has been set. A further follow-up spray of 02% potassium dihydrogen phosphate + 0.5% urea will promote fruit expansion and swelling. Potassium phosphate can also help to improve frost and heat resistance in the event of bad weather. Potassium also promotes fruit colour change. Improves commercial quality.
Before tomatoes turn colour, a critical period for quality, it is important to remove old yellow leaves that can block light under the fruit in time to increase light penetration and ensure light is available for even colouring. A moderate amount of potash should also be applied.
Potassium is very helpful in colouring tomato fruit. However, potash must be followed up before colour change. Absorption of potash is slow and largely ineffective if applied during the colour change period.
The lower leaves of the tomato should not be thinned out when the opposite leaves start to turn red. Otherwise it will weaken photosynthesis and lead to an inadequate supply of nutrients, which will ultimately affect the colouring of the fruit. If you are growing tomatoes in a greenhouse, you will also need to do a good job of temperature control. The temperature should be controlled at 22-28°C during the day and 15-20°C at night. Also try to increase light, using supplemental lights on cloudy days.