Maybe it’s the Italian blood coursing through my veins or maybe it’s the challenge, but growing great tomatoes is a priority for me every year. For me, great tomatoes start with growing strong seedlings that will transplant well. My seed starting post goes over my top basic tips for starting all seeds but different varieties have their own little tricks and tomatoes get a lot of special treatment in my seedling room!
Starting your own tomatoes is very satisfying and it allows you start the varieties you want in the amounts you want them. If you do it right you will also have really strong seedlings that will produce well.
Every tomato grower has their own protocol for growing tomatoes successfully. I have tried a few different methods and am always learning and making changes, but I am really happy with the tomato seedlings we grow so am sharing my method.
We start our tomatoes in flats with 72 cells. This works for us, some people start them in smaller cells, mostly for space saving purposes. Heat is extremely important for good germination of tomato seeds, the temperature should stay at 25 degrees Celsius or higher. Heat mats really help with temperature control and making sure the soil stays warm enough. I don’t like using plastic domes because it does not allow for good air circulation and you can get mold growing on the soil surface and damping off of seedlings. However, sometimes to get the soil warm enough, you need to use them. We have found a higher dome with vents in the top, while still not ideal I think these are better than the low domes without vents. But the moment seeds have germinated and sprouts appear, you need to remove the dome to allow for good air circulation. Consistent moisture is also important for good germination, so make sure you are watering as soon at the top of soil begins to dry out.
**A note on soil blocks. You may be familiar with soil blockers for starting seeds. When I first read about soil blocks in Elliot Coleman’s “The New Organic Grower”, I was hooked and couldn’t wait to try them. There is a lot about them to like and I would love to love them, but I don’t. I do still use them for some crops but not tomatoes and peppers. I find when potting up, though the blocks make it quick and easy, I don’t get the developed root systems I want. I also find it difficult once they are in the final large block to keep the block sufficiently moist and transplanting into the garden is cumbersome at that size. But if you find they work for you – that is great!
Potting up is really important with both tomatoes and peppers. We pot our tomatoes up as soon as they have their first set of true leaves, this is often about 1 week after they have sprouted. At this time if you look at the bottom of the cells, you will see some roots starting to poke through, they may not be root bound yet but trust me they will appreciate the space.
We transplant our tomatoes into 4 inch cells and that is where they stay until we transplant them out. I used to be nervous about potting my seedlings up – that I would disturb the roots or not do it right and they would die. Now I don’t worry at all. The biggest key to success is WATER! I give the seedlings a thorough soaking prior to transplanting. Then I fill the pots with soil mix that is lightly moistened. Gently remove the seedling from its cell and place it into the pot. Then finish filling the pot until the soil is just below the first set of leaves, this means you are covering much of the stem. Tomatoes are able to send roots out from their stems when in contact with soil. By covering their stems up to the leaves, you are making sure that they develop a really strong root system and you are preventing them from becoming leggy and stressed. After you have finished potting them up, water thoroughly and place back under lights.
I have to say it always amazes me how the tomatoes take off right after I have potted them up. Now is the time to really prevent legginess. To do this I keep the lights 3-4 inches above my seedlings. As the seedlings grow, I raise the lights. Read my seed starting post to see how I manage the lights in our seed room.
Hardening off is incredibly important with all transplants but I do find that tomatoes are a bit finicky and to really flourish once they have been transplanted, you need to take some time to do it properly. Most people think we harden off to get seedlings used to the cold – true, however, the bigger issues are heat and humidity. More seedlings die from heat shock and dry air or wind then they do from cold. Having said that, unless you are transplanting tomatoes out into a cold frame or under cover, DO NOT transplant our until after all risk of frost has passed because tomato seedlings will not tolerate frost.
A week or two before I transplant out, I bring the seedlings out of the seed room and place them in an unheated room in the house. I leave them there and reduce the amount of water I give them. Then I start taking them outside, just for a few hours. When I first take them out, I place them in a shaded area out of direct sunlight. I increase the time they are outside over a few days and then transplant them.
When transplanting them into the garden, we make sure our soil is well prepared. We amend our soil with lots of compost, chicken manure, sea kelp and a small amount of lime for calcium. When you transplant the seedlings in, again cover the stem to the first set of leaves. The key to success once you have transplanted, is to stay on top of watering for the first few days while the tomatoes get rooted down. Then take a deep breath and smile because you have successfully transplanted your seedlings and area ready to watch them grow…and man do they grow! Then will come pruning and trellising – but that is for a future post!