Updated/Fact-Chacked on March 9, 2022 by John
You’ve done your research and chosen what seeds you want to grow. You’ve bought your seeds and learnt about what kind of soil they need and what their ideal conditions are. Depending on what you’re growing, you will have planted your seeds either in a pot, or directly into the soil of your garden.
If you’ve done everything right so far, you will have had the great satisfaction of seeing your little seeds sprout. This is also known as “germination”, which is the stage of planting where you see a small stalk and a couple of tiny leaves.
At this stage, your seedlings are delicate, so it’s really important to know what to do next. This article will give you a general idea of what’s needed to transform your seedlings into full-grown plants.
My Seeds Have Sprouted, What Do I Do Now?
Now, you need to make sure you give your seedlings everything they require. Think of it as like taking care of a baby – if you provide for them, they will thrive (as long as they don’t catch a disease, but we’ll come to that later).
They need several things:
Seedlings need the correct light, otherwise they might end up pale and weird-looking. A windowsill or a greenhouse is ideal. This is because seedlings have to have both light and darkness, so the sunlight of daytime and the darkness of night are the perfect combination for them.
Keep an eye on your plants to ensure the heat of the sun doesn’t dry them out. It’s also worth turning them twice a week so that they grow nice and evenly.
If you can’t offer natural light, you might want to invest in a grow lamp with a fluorescent bulb. These are great because they simulate real sunlight, which is split into two different varieties – red light and blue light.
For the best results, you should position your grow lamp a few inches above your seedlings, but make sure that the warmth of the lamp isn’t overheating them.
They won’t do well if they get too hot, so the rule of thumb is: if you put your hand at the level of your plants and it feels warm, your lamp is too close.
Everyone knows that plants need to be watered, but how much water and how often can be a tricky question. As a general rule, you should water your seedlings 2-3 times a day. The humidity of your growing environment will influence how much water they retain, but you should aim for them to be moist at all times.
To test the moisture, pop the end of your finger about an inch into the soil. If it’s dry, your plants need water. If it feels wet, you’ve given them too much love. Soil that is moist to the finger’s touch is just right for your little seedlings.
It’s worth mentioning that, if you’re using a spray bottle to water your plants, take care that the force of the spray doesn’t blast your delicate baby seedlings straight out of the soil. They wouldn’t like that and it could undo all your hard work. They will do much better with a gentle touch, and they prefer slightly warm water to freezing cold.
Plants adore a good, hearty meal. A few days after their first little leaves sprout, you should start to feed them with a fertiliser that is high in phosphorus. This mineral helps their roots to develop, and it comes in either organic or synthetic versions. Mix your fertiliser with your water and feed your seedlings about once a week.
If you have used a potting mix, take care to read the instructions. If your mix already contains fertiliser, you won’t need to give your seedlings any more. If you over-fertilise your plants, they can become weak and vulnerable to disease.
When your seeds are first planted, you need to keep them covered so that they sprout. Once they have sprouted, you can take off the cover and let the little shoots and leaves get some fresh air.
During the first week or so, you can cover them for a few hours a day to stop them from drying out. This is more important if they’re on a very sunny windowsill, or in a hot greenhouse.
If your seedlings have a decent airflow all around them, it will help them to grow into sturdy and handsome full-grown plants. If you don’t have much natural air in your growing environment, you can use a gently blowing fan for a few hours a day.
Your seedlings need a bit of space to be able to grow properly. You need to think about their roots under the soil and how much room these might take up. Lots of people end up with too many seedlings in a pot because they plant lots of seeds in the worry that some might not germinate. If this happens to you, just pull out or cut off the weaker, more puny seedlings. This might seem a bit mean, but it will ultimately give the healthier plants the space they need to thrive.
If you think your seedlings need more room, you can always repot them into a bigger container. This is also called “transplanting”.
If you’re doing this, remember that you’re dealing with delicate baby plants. Don’t be rough and try to grab them by the stem – they could break. Instead, you should push them up from underneath the soil, so that the roots remain intact.
One of the most common reasons for the demise of seedlings is a nasty fungal disease known as “damping off”. You’ll know if your plants have succumbed to this if they’re healthy one day, then dead the next.
If your little seedlings fall victim to damping off, alas, there is nothing you can do to save them. Prevention is the key.
Here are a few tips to help your plants avoid this awful fate:
- Use commercially produced compost – this is normally free from the organisms that cause damping off.
- Try to use new containers, or ones that have been thoroughly cleaned. Don’t use any pots or trays that have previously had damping off issues.
- Avoid overwatering your seedlings, and make sure they have good airflow.
- Don’t put too many seedlings in one pot.
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John Green is a 46-year-old graphic designer living in Durham. John is RHS level 3 certified and owns an allotment in Durham.