Start seeds 8-12 weeks before last frost. Dwarf and microdwarf tomatoes can be started a bit later, about 6-8 weeks before your last frost.
Sow seeds 1/4" deep into potting soil. If planted too deep, seedlings may struggle to emerge. If planted too shallow, the seedlings may emerge with 'helmet head.' This is when the seed coat is attached to the seedling's cotyledon, and can prevent the seedling from taking in enough sunlight to thrive. The seed coat traps the cotyledons, rendering them unable to fan out and make room for the first set of true leaves to grow. If this happens, try not to pull the seed coat off, as this often can damage the cotyledons. Wet the seed coats down with a spray bottle every couple of hours to soften up, allowing the cotyledons to push free.
Keep at 16-30C. Using a heating mat will speed up germination, but is not necessary. Keep in a warm sunny area and use a clear dome if possible. This helps trap warmth and humidity- aiding in germination. Water from the bottom if possible when soil begins to dry out.
Seedlings should emerge in 7-21 days.
Use a well-draining soil. We like to use something with good drainage, to prevent soggy soil and dampening off disease. It is important to make sure your seeded trays are kept fungus gnat-free, as fungus gnats are very proficient at spreading molds and fungus that will kill off small seedlings, or even prevent from germinating at all.
Provide very bright sunlight in a south-facing window if possible. Even better, use grow lights. If you have a short growing season it is important to give seedlings the best head start possible, and growing under lights prevents seedlings from becoming too leggy.
Keep grow area well ventilated. Keep seedlings from being too crowded, as airflow to the stems of the plants prevents mildews and other fungus from growing. Keeping a small fan gently blowing towards the grow area will mimic wind, and tell the tomato plants to grow sturdier stalks.
Inspect plants often for pests and diseases.
Once half of the seeds have germinated, the dome can be taken off. Keeping a dome on for too long can cause too much humidity and encourage molds, fungus, and diseases.
When seedlings emerge, they have enough energy stored via the seed, to produce photosynthesizing leaves. This is when we start fertilizing our seedlings with a very very weak fish emulsion dilution.
Once seedlings have one true set of leaves, up-size into a bigger pot. Continue feeding every two weeks with worm castings, compost, fish fertilizers, and other organic and natural fertilizers.
Keep up-sizing tomatoes into bigger pots as needed. Once they start becoming root bound is a good time to pot up.
If the plants start putting out flowers, pick them off until 2 weeks after tomatoes have been planted in their final place.
Around 2 weeks before your last frost date, tomato plants will need to start being acclimated to being outdoors. On a warm day, move seedlings outside in a shady and sheltered spot of the yard for 10 minutes. Every day, increase this time, and gradually expose the seedlings to direct sunlight.
Keep an eye on nighttime temperatures. Once nights are mostly above 10C, the seedlings can be planted.
Here in Sturgeon County, Alberta, our last frost date is May 23rd. We usually wait until the first week of June to plant our tomatoes if growing outside, but plant our greenhouse and high tunnel tomatoes on May long weekend.
Add rich compost or other natural fertilizer when transplanting outdoors. We also like to add some mycorrhizae powder into the hole in the ground when planting, so that contact with the tomato plants roots is made.
Pluck off the leaves and branches on the bottom 1/3 of the plant. Plant the seedlings deep, so that the bottom 1/3 is completely buried. New roots will grow along this buried portion of the tomato, which ensures a deep root system. This allows the tomato plants to access water deeper in the ground when things are extra dry and hot mid-summer.
If the plant has any blooms on it, now is the time to pluck those off. This will encourage the tomato to put more energy into expanding and growing its root system before fruiting. Tomato plants with nice big root systems will be better equipped to take up water and nutrients, outlast dry spells, and overcome diseases.
Once the plants have been growing in their final place for 2 weeks, discontinue pinching blooms. The tomato should have recovered from any transplant shock and grown its root system, and be ready to start producing flowers. (This is when you can start bagging blooms if you are saving seeds)
In early stages, as flowers start setting to fruit, ensure tomato plants are getting enough magnesium & calcium. This, along with consistent watering, can help prevent blossom end rot.
or best flavor, pick tomatoes when they are fully ripe. Tomatoes will continue to ripen up on vine until first frost.
It is best to pick all tomatoes (even the green ones) if there is threat of a frost and plants cannot be protected. If tomatoes freeze, they will start to go bad before they fully ripen, so it is best to get all of them inside. Because we have such a short growing season, we always end up with green tomatoes in the fall. These can still be eaten! We lay them out in a single layer in a dark room in boxes or on newspapers. Over a couple of weeks, they will start to turn color. Pick the ripe tomatoes every couple of days. Compost any that are starting to get mushy, have large cracks, mold, or just seem off. After 2-3 weeks, any left over green tomatoes that have not gone soft or mushy can be used in recipes such as green salsa or green fried tomatoes.
Microdwarf tomatoes are a great way to get into growing your own food! These mini tomato plants are much more forgiving and produce fruits in less time than regular-sized tomatoes, making them very easy to grow!
Start your indoor tomatoes in late summer or early fall for a Christmas harvest. Start indoors in December and January for a spring harvest. If you want to grow microdwarf tomatoes on your patio or in your garden in the summer, don't start them at the same time as your full-size tomatoes. Wait until 6 weeks before your last frost date to sow these.
Sow seeds into good-draining potting soil. Keep moist and covered. Tomato seed germination happens best between 20C - 27C (65-85F)
Seed germination mats greatly speed up germination. If you do not have a mat, no worries... keep your seed trays at room temperature, a warm sunny window with afternoon light helps.
Little seedlings will pop up within 7-21 days. Once you see germination, it is safe to remove the tray cover if using one
If it's been more than 2 weeks and still no seedlings, we found that sometimes some varieties are happier with less moisture, and will pop up shortly after adjusting the humidity. We do this by removing the germinating dome or cover, making sure not to let the soil dry out
Once the seedlings get their second set of true leaves is the ideal time to pot up into something a little bigger... a 4" or 6" pot. Once the plant shows an established root system in that pot or that it's gearing up to put out flower buds, its time to pot up into the final 3/4 to 1-Gallon pot. I find this happens around 5-6 weeks post-germination
Use pots no bigger than 1 gallon unless growing bigger varieties like Christmas Tree or Dark Stripe. Most micro tomatoes truly do not benefit from a bigger pot, and will just put out more foliage and not necessarily more fruit
Be sure to place your tomato plant in a bright sunny room if you aren't using grow lights full-time. If you can't provide 14+ hours of sunlight per day, it would be very beneficial to give the tomato plants some supplemental indoor lighting in the early mornings and late evenings. Be sure to use full spectrum lighting.
Snip the bottom leaves off the microdwarf plants closest to the soil as they grow. This prevents diseases and pathogens from spreading to your plant's leaves from the soil by allowing more airflow. This can be challenging for very small varieties like Nina Neutron or Baby as the plants are so small and low to the soil... in these cases I make sure to water from the bottom of the pots and place in the best ventilated area in the grow space
Check your plant regularly for pests. Inspect the stem, branches, tops of leaves, and most importantly, the bottoms of the leaves. Indoor conditions make the best home for those pesky plant bugs as it's warm and cozy and there are generally no predators for them inside. They can get out of hand pretty quickly if they aren't caught early! I like to thoroughly inspect each plant when I fertilize, which is usually bi-weekly
Aside from keeping the stem foliage cleared for airflow at the base of the plant, microdwarf tomatoes don't really need to be pruned or have suckers removed. Because the plants aren't really growing up, they don't need to direct all their energy to a long main stem. I think the only micro tomato I've had to prune because it's just too unruly is 'Hardin's Mini'
Tomato flowers are self-pollinating so no need for bees or other pollinator friends. To ensure each bloom is self-pollinated you will need to help the flower release its pollen. This can be done very easily by tapping or moving the blooms with your fingers. I find the best results come from using an old electronic toothbrush with the brush removed to briefly touch the branches of the tomato plant with. The tomato blooms think that a bee is visiting, and release the pollen, which in turn pollinates the flower and ensures that the fruit will set. I do this daily or maybe even every two days when the tomato is actively blooming
Keep up on organic fertilizer. I mostly stick to a bi-weekly feed schedule. As the tomato plants are growing in smaller containers, they will use up available nutrients much faster. I will link below to some of my favorite products or websites I use to keep them fed. I use Frugal Bush Bunny's foliar spray (see link below) on the plants when they are smaller, and as they get bigger I stop using as a foliar spray and instead I use it as a soil drench every 3 weeks or so for an extra boost. It's full of good stuff like calcium (prevent blossom end rot), mycorrhizae, humic acid, kelp, magnesium, +more
When the tomatoes appear the be at their breaking point (when they start turning from green to red/orange/yellow/etc) scale down on large waterings. Saturating the soil can make a tomato taste bland when watered too much in their ripening stage. For the best flavor I like to give smaller amounts of water at this time and go as long between watering as possible without placing too much stress on the plants. While the tomatoes won't be as lovely as the sun-kissed tomatoes of summer, they are better than your generic imported winter grocery store tomato
A tray of freshly germinated microdwarf tomatoes. They are much shorter than regular size tomatoes when they emerge from the soil, as you can see in this photo
A micro dwarf seedling before being potted up into a 6" pot. Pictured here is Moonglow Garden's 'BZN F1' at 5-weeks post sow
Your micro tomato should be in it's final pot before it reaches this size. I like to make sure they are in their final pots at around 5 weeks post-germination. Give them 1-2 weeks to develop roots in their last pot before they start to flower.
Smaller micro tomato varieties do best in 3/4 to 1-gallon pots.
Larger varieties do best in 1-gallon pots
Or grow two smaller varieties in a 1.5-gallon pot
Experiment with what works best for your grow space
We found that putting micro tomatoes in larger pots does not necessarily mean more fruits.