Growing tomatoes in pots can be a fun and rewarding project. Potted tomatoes fit on a balcony, in your windowsill, or even in containers in your yard. For rich tomato flavor, nothing quite beats a sun-ripened tomato that you just picked off of your own plant.
Tomatoes are one of the many, mostly non-finicky seeds that you can start and grow to fruiting, even if you’re new to gardening. The best tomatoes for containers are dwarf tomato varieties, these are also known as determinate tomatoes. This means they have a self-limiting growth gene, and on-average will only grow 3 foot tall. If you have a very small space, micro toms, or micro-tomatoes only grow 6-12 inches. Micro-tomatoes are perfect for hydroponic growing, and only need a 6″-8″ pot for container growing.
Micro and dwarf tomato varieties normally blossom in a single flush, and fruit in a single flush. Indeterminate or traditional tomato varieties grow throughout the season, and blossom and fruit throughout the season. So, there’s more chance of losing green tomatoes to frost with indeterminate varieties than with determinate or micro varieties.
Your dwarf tomato varieties will have larger slicer and sauce tomatoes included. So if you want to grow tomatoes for sauces, dehydrating, or slicing for sandwiches, there will be a dwarf variety to fit your needs. Also, since their flowers and fruit happen in a smaller window during the growing season, it can be easy to harvest enough for a batch of tomato sauce.
Micro-toms are currently only cherry tomato varieties. These are great for fresh eating, salads, snacking, and sometimes dehydrating. Most micro-toms only produce a few handfuls of tomatoes. However, kept indoors a micro-tomato can have more than one flowering set in it’s lifetime, since it won’t get hit with frost. The plant will get a little sturdier, thicker, and more productive for each flowering and fruiting cycle it goes through. On average, a single micro tomato plant can go through 3 flowering and fruiting sets per year, as long as it’s kept protected from frost, and as long as you have space.
Growing Tomatoes In Pots:
Chose your tomato seeds based on your space, and what you want tomatoes for. For example, if you have a window-sill then a micro-tomato variety will be best. If you’re working with a patio, balcony or other small outdoor space, then some determinate tomatoes will be best.
If you want slicers, aim for a variety like Brandywine, or other large fruiting slicer type variety. For sauce, a roma type works best. For snacking, a cherry or smaller fruited variety can be a nice variation. There are dozens of different tomato varieties, from purples, pinks, white, yellow, green, and red varieties. Varying in sizes from the tiniest cherry tomato, to several pound slicers. Tomatoes can be a great way to get into heirloom and unique plant varieties, and their great for homeschool and kidlet led garden experiments.
When growing tomatoes in pots, you’ll want to chose a pot relevant to the size of the finished plant. Most tomatoes can be started in seedling cells, and then transplanted into larger pots as they grow. A micro tomato only needs a 6-8″ round pot for full growth. A dwarf tomato may need up to a 3 gallon, or maybe a 5 gallon for large fruited slicing varieties.
You’ll need a veggie potting soil blend, or to make your own blend with sterilized compost, peat moss, vermiculite and perlite. Especially for indoor containers, use sterilized potting soil. If you’re planting in outdoor containers, with established seedlings, a less sterile soil mix could be used.
You will also want to use fertilizers at some point during the growing season. A good all-purpose non-chemical option is Alaskan fish fertilizer, it’s good for promoting early growth, and can help with the production of leaves and stems. Worm compost, and a slightly higher potassium fertilizer are good to help promote blossoming and fruit set.
If growing slicing tomatoes, a tomato cage or other support may be necessary once blossoming starts. I like putting the tomato cage in the pot when the plant is about half grown, so that there’s no chance of breaking branches when manipulating the plant to fit into the cage. You can also simply stake the tomato plant.
Transplanting into Pots:
Whether you’re starting from seed, or if you purchase an established tomato seedling, you’ll need to transplant the tomato plant at some point during the growing season. Before starting transplanting make sure you have a clear workspace, your potting soil, and your fresh clean pots. You can re-use planting pots, simply wash with hot soapy water first to remove any old soil and bug or fungal potential. Some people like give their re-used pots a quick bleach rinse as well, then drying them in direct sunlight for a few hours to UV clean them too.
Make sure the drainage holes are clear, and if using recycled containers for pots, make sure you make adequate drainage holes.
Water seedlings well the night before transplanting. This helps prevent root breakage, while still making sure the soil is not too wet to handle. Watering right before transplanting will help if the plants are dry, but the root ball can be harder to work with. If you need to water just before transplanting, try to time it a few hours in advance so that the soil moisture is even and you don’t end up with dry patches and muddy patches in the root ball.
Partially fill the new pot with potting soil, and make sure the potting mix is lightly damp. It should hold together when squeezed, but not be so wet that it’s in danger of compacting. The fresh potting soil will have new nutrients for the plant to access, so there’s no need to fertilize at the time of transplanting.
Loosen your seedling from it’s pot, and loosen the root ball. Place in the new pot. With tomatoes, you can also remove the seed leaves, or cotyldens and lowest set of true leaves to enable the plant to have soil come up the stem to develop more roots. Do not remove true leaves if the plant has 4 or fewer true leaves, only remove true leaves to plant the stem deep IF the plant is leggy, or has at least 6 sets of true leaves.
Add more potting mix to fill the new pot and firm it in around the tomato plant. Water well, and set the plant back under your grow light, or in full sun if it’s already hardened off. When working with outdoor determinate tomatoes in pots, you can repot them during the growing season if you started with a too-small pot. Many sauce and slicer type determinate tomatoes like being in a 5-gallon pot, and will produce better in a larger pot.
Indeterminate tomatoes should be in a minimum five gallon container, but can go through two or three transplanting sessions to get there too.
If using very large containers, like a 15 gallon grow bag, or a bathtub, you will want to mulch the surface of your container. A simple straw or shredded paper mulch will help keep moisture in the container and may reduce the need for daily watering.
In summer, water small containers frequently, up to twice per day, to keep the plants happy and healthy. Especially if your small containers are in direct sun. Larger containers can go a little longer between watering, especially if they have a water saucer underneath that lets you give a bit extra in the morning so the plant can draw it up during the day.
Feeding Container Tomatoes:
After the tomato plant is well established, it is good to fertilize or feed, the tomato plant at least once every two weeks during the flowering and fruiting phase. A lot of gardeners like Alaskan fish fertilizer, as a natural fertilizer with a good balance. If you have local raccoons, it may be better to use compost or worm castings, or a simple compost tea made out of either of them, instead.
Potassium deficiency can lead to purpled stems and leaves in tomatoes. However, purple and black tomato varieties can naturally have a purple tinge to their leaves and stems. Also, cool spring weather can sometimes lead to purpling, due to the plant being less able to draw up the nutrients it needs. When the weather warms, cool-related temperature changes should resolve themselves. You can make banana water, by soaking banana peels overnight, to give the tomatoes a very light potassium boost.
Blossom end rot is also a concern with tomatoes. BER, as it’s also known, is caused by a calcium deficiency in the plant. Inefficient or irregular watering can cause the plant to take up less calcium than it needs from the potting soil. While some people add calcium tablets to their plant pots, or garden planting holes, others add crushed eggshells to keep some extra calcium available in the soil. The main concern, however, is keeping watering consistent and thorough.
While it can be nice to see a bushy, green, tomato plant, too much nitrogen or a high nitrogen balance fertilizer can cause excessive vegetative growth and reduce or prevent flowering. Plants need more phosphate and potash than nitrogen during fruiting.
Indeterminate tomatoes will have a vining growth habit. These tomatoes especially will need pruning to keep them from overtaking your patio, containers, or balcony. Prune to a single stem, and prune any excess growth over 3-4 feet, especially side growth. Let the central zone establish with flowers and fruit, and when you have 4 weeks left till your first frost, make sure to prune off any additional flowers that the plant attempts to set. This will help your harvest ripen on-time so you can harvest tomatoes before frost.
Your determinate, dwarf, and micro tomato varieties normally do not need extensive pruning. The only pruning a determinate tomato may need is a bit of thinning to let sunlight into the center, or to help train the plant to it’s supports.
If you are using 10-gallon or larger pots, you can still do companion planting with tomatoes, even in containers. Flowers like marigold, and herbs like basil, grow well alongside tomatoes and tomatoes grow well alongside them. Dwarf marigolds can provide a very pretty layer, that also helps protect the pot’s soil from sunlight and can help keep the pot from drying out excessively, especially paired with mulch.
For in-ground gardens, marigolds help repel soil nematodes that cause root knotting and prevent the plant from taking up adequate nutrients. In pots, the marigolds encourage plant growth, and add a pretty, flower, layer to your containers.
Basil and tomatoes simply seem to get along really well. Basil also goes great in tomato sauce and tomato based dishes. So, if you’re planning on growing basil anyway, place a plant in each of your largest tomato pots and see what happens.
If you don’t have space for even a few containers, you may still have space for microgreens and the space and ability to grow your own salads – all year round!
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