Nothing says summer like a freshly picked, ripe tomato from the vine. However, in cold climate and short growing seasons it does not happen very often, if at all. Most tomato growers around here pick green tomatoes in the fall and after ripen them indoors. Our summer seem to be just too short and too cool to ripen tomatoes.
Tomatoes are a summer crop. They die when freezing weather occurs. But they also do not like it cold, windy, and wet. In order to grow tomatoes and get them to ripen they need a warm, dry spot. However, with summer night temperatures dropping under 10C (50F) tomatoes will be shivering. What to do? With these 9 simple tips we too can harvest ripe tomatoes in the summer.
To achieve ripe tomatoes in a greenhouse is much easier than it is outdoors, and I think it is the best way to go for us northern growers. Still, I will concentrate here on outdoor growing and just give some tips on greenhouse growing.
1. Choose an early tomato variety. Not all tomatoes are the same. Some ripen faster and tolerate cool weather better then others. Generally determinate or dwarf tomatoes are earlier and better suited for outdoor growing. Caseys heirloom tomatoes catalog has a Guide to the Best (Non-Cherry) Tomatoes To Grow Outdoors in Calgary (zone 3a) and also a Guide to the Best Tomatoes to Grow in Pots. You might find your favorite variety on that list. We have had great success with Mano and Native Sun. However, other suppliers have great tomatoes for outdoor short and cool season, too. Just make sure they are early. It is best to get seeds from local growers, or a climate similar to yours. Those tomato plants have already been adjusted to the weather, and will grow and produce better.
2. Start tomatoes about 6 – 8 weeks prior to planting them out. You want the seedling to be just about setting out buds. Not bloomed yet. In our area, our last frost date is May 26. Since tomatoes do not tolerate any frost, we might have to wait till June 1 to plant them outdoors. So the earliest to start them indoors would be beginning to mid April. If you have grow lights or a very sunny window, the seedlings will grow faster so plant them later. It does not work to start seedlings earlier to get ripe tomatoes earlier. If the seedling is overgrown, it will suffer, and you will get ripe tomatoes later, or not at all. Read all about starting tomatoes from seeds here. If you do have a greenhouse, you might be able to plant them up to two weeks earlier.
3. Choose a sheltered location. Location is everything when it comes to growing tomatoes. If you have a spot in your garden that is too hot for most crops, it might be just right for tomatoes. If you do not have a warm spot in your garden, but on your deck, tomatoes can be grown in pots or grow bags. We grow ours in grow bags on our driveway. The heat from the concrete and the black bags will help to keep the heat loving plants warm. See how to grow in grow bags.
4. Add manure to the soil while planting. Manure tends to warm up the soil better. Especially horse manure is known for that. Just make sure the manure is composted. Later in the season, water with compost tea. The boost will help the plants to grow better and mature earlier.
5. Water with warm water. Watering plants with tap water may or may not harm beneficial bacteria in the soil, but it sure is to cold for heat loving plants. It is better to use water that is warmed up from the sun. That way the plants will not go into shock every time you water.
6. Cover your young tomato plants. You get what you pay for, or in this case what you invest in. To plant tomatoes in open field, and leave them to the elements, will not lead to early ripe tomatoes. Give them as much protection as you can give outdoors. I like the Plant Protection Blanket, it is light weighted and can be left on for days, as the weather permits. You can cover a tomato bed with it, or wrap an individual plant. Jakob also built a wind barrier for the tomatoes out of recycled windows. You can also use a Kozy Coats Water Filled Garden Teepee, add water and place the filled teepees over the plants. The Kozy Coat becomes an igloo, keeping in the heat and warmth from the soil.
7. Add thermal mass. The Kozy Coat already works as protection and thermal mass, or simply put a milk jar filled with water next to the plant. Rocks work the same way, build a little wall behind your plants, the rocks will heat up during the day and give the heat back at night, giving some wind protection as well. Thermal mass seems to be even more important in a greenhouse (See water tank in a greenhouse). A plastic covered greenhouse gives you only about 3 degrees at night, but heats up the place beyond comfortable during the day. The fluctuation is very hard on plants. Thermal mass helps to regulate it. We also added a radiator to the thermal mass, that worked really great.
8. Hand pollinate. Pollinating tomato plants is very easy, just shake the plants, or the flower cluster a bit, that’s it. Sure, wind or insects can do it for you, but while waiting for them you might lose some precious ripening time.
9. Prune your plant. Most determinate plants do not need pruning. Still, if you have very big tomato clusters, cut them back some, they will ripen faster. If the plant is indeterminate, definitely prune it back. See whether to prune or not to prune tomato plants. Outdoors you want to prune the plants even more than in a greenhouse. You will get less fruit, but they will be bigger and ripen faster. It’s the better choice.
The more protection, love, and care you give, the earlier the plant will grow and ripen. However, some summers are better than others for growing ripe tomatoes around here. If the weather is just too cool, and it snows in between, do not beat yourself up about it. Tomatoes do ripen nicely indoors. Happy tomato growing!