For healthy plants, punctual sowing, fertilizer and the right watering are one thing. But there is much more to plant care in order not to ruin the progress made so far. Because not only sudden frost can damage your young plants, too much sun during the first time outside also makes them suffer. Therefore, so that your initial effort is not in vain, you should not only wait for the right time to plant them, but also harden off your tomato plants. We explain how to do this below.
Why toughening is so important
The plants were used to being pleasantly warm and relatively shady inside. If you were to change these conditions suddenly instead of gradually, you would be making life extremely difficult for the plants. What will change from now on:
- Temperatures will fluctuate. Indoors, the room temperature was relatively constant, but outdoors it alternates from warm to cool and vice versa.
- The sun’s rays are significantly stronger. True, in the room or greenhouse, the plants stood on the windowsill and very brightly. But the amount of direct radiation was significantly lower and also somewhat weakened by the glass pane. That is why the tomatoes can get sunburnt if the sun is suddenly stronger.
- Inside there was no wind, but now there are sometimes stronger winds against which the plants have to be hardened. However, this part is not so much part of the initial hardening, but happens gradually by itself.
When can tomatoes go out?
As you know, nighttime temperatures play the biggest role here. Because up to a certain point there is still a certain risk that frost will appear and damage the tender plants. For this reason, more sensitive plants are also allowed outside after the ice saints. However, you don’t want to leave the tomato plants outside around the clock to harden them off, but put them back in at night, which is why you can start earlier here. So when can you put tomatoes out?
You can get started from the end of April or the beginning of May at the latest. Then it is already warm enough during the day to be able to harden your tomato plants.
Hardening tomato plants in a few days – Here’s how to do it right
In the following we would like to give you a small guide with which you can successfully harden off your tomato plants. You have two options for this:
- They take their time and plan up to two weeks for the adjustment phase. In this case, the plants can stay outside all day and you don’t have to keep track of the hours of “outdoor” to bring them back inside in time.
- A “crash course” takes less time overall, but it also requires you to be on site to bring the plants back in after a certain amount of time.
So that you don’t have to carry all the plant pots out and then back in again individually, it is worth using a basket, tray or box in which you can transport several plants at the same time.
In all phases of hardening, you should choose locations that are as sheltered from the wind as possible, because the plants are not used to wind either. That doesn’t mean they can’t handle the odd gust of wind, but it shouldn’t be too blustery.
Harden off tomato plants in 2 weeks
week 1
- The plants can finally get some fresh air, but be careful where you place them. This should be shady in any case, and by shady we really mean that absolutely no direct sunlight should reach the tomato plants. Sometimes it only takes a few minutes for the still sensitive leaves to get burned by the sun’s rays.
- The tomatoes can then spend the whole day in this shade. Only in the evening or before the sun goes down and it gets much colder can you bring the tomato plants back into their quarters.
- It stays in this daily shady spot for 5 to 7 days.
week 2
- The tomatoes can do with a bit of sun now. That’s why they can now be placed in the penumbra, where you get a moderate amount of sunlight. In this way, the tomato plants can be hardened off in a gentle way without risking burns.
- If the nights are not that cold (over 10 degrees), the plants can stay outside, but preferably protected from the wind.
- To be on the safe side, or if the weather forecast predicts low temperatures, it’s better to put them back inside.
- After about 5 days of partial shade, you can already dare to put the plants in the sun and then plant them in the bed after the ice saints.
Last minute hardening for your tomatoes in a week
If you missed the point in time and are now a little late in hardening the tomato plants, you can also carry out a “crash course”. However, you should be available in good time to store the young plants in good time.
Day 1 to 4
- Put the plants outside for about 2 hours. Shade is recommended as even minimal amounts of direct sunlight can cause damage. Also protect the tomatoes from rain and drafts.
- For the next 3 days, increase the time period again and again.
Day 4 to 7
- The plants can now feel the sun.
- Choose either partial shade all day or a few hours of direct sunlight on an east or west side.
- Under no circumstances should the young plants go straight to the south side, where the sun is strongest, especially at midday.
- After the acclimatization week is over, you can follow the night temperatures and leave the plants outside permanently.
- After the Ice Saints, the plants are hardy enough to be planted out in the bed and survive both the stronger sun and the lower temperatures at night.
