Growing Tomatoes Indoors: A How-To Guide

There is hope for tomatoes in the winter!

Growing tomatoes indoors, a step-by-step guide:

  1. Step 1 — Choose the tomato seed. There are two types of tomatoes: determinate, which means they only grow to a compact height and stop growing after they produce one round of tomatoes — which all ripen at once, and indeterminate, which means they will grow and produce fruit in a vining fashion, blooming, setting new fruit, and ripening all season long. They require more attention because you will need to do a lot of pruning, but are good for indoor growing.

There are thousands of varieties of tomatoes; several hundred named varieties are readily available as seed or starts. Choose plants to grow based on:

  • How you plan to use the fruit after harvest: fresh eating, cooking, canning, preserving, or drying. Choose beefsteak and slicing tomatoes or cherry or miniature tomatoes for fresh eating; choose paste or cooking tomatoes for cooking
  • The length of your growing season: early, main crop, or late harvest
  • The size of the plant you can accommodate in your garden or container
  • Whether you plan to stake or cage the plant or let it sprawl
  1. Step 2 — Choose a location for the plants. Tomato plants need at least 8 hours of full sun per day in order to produce fruit. Near a window would be an ideal location, as long as there is not a draft, since tomatoes are sensitive and growth could be stunted if they get too cold. Temperature should be at least 65 degrees Fahrenheit, although best growth occurs between 75–85 degrees Fahrenheit. This can be difficult to achieve, so grow lights or portable greenhouse are always an option.
  2. Step 3 — Sow your tomato seeds. This means the seeds will be planted so they can germinate and begin to grow. It is best to plant in flats (starter trays) using PittMoss Performance, which is ideal for seed germination.

You should place the seeds ¼ inch deep. The seedlings should be in a warm location to germinate, the top of the refrigerator is ideal but if that is not practical the sunny location chosen above will be fine, and you can cover the plants with foil or plastic wrap to keep the heat/moisture in. Be sure not to over-water the seedlings — PittMoss has an amazing capacity to retain water and the best practice is to keep your PittMoss on the dryer side.

  1. Step 4 — Move/Transplant your seedlings. Once germination occurs in 5–10 days, you can remove their cover and move the seedlings into new pots and to the brightly lit area that you chose in Step 2. Once the seedlings have reached about 3 inches high and have 1–2 leaves, it is time to move them to a 3.5–5 gallon pot. Place the whole seedling on top of the PittMoss. It is good to put a few rocks at the bottom of the pot; this will help ensure good drainage by keeping PittMoss from falling out of the hole(s) and clogging it up later. Fill the container about a third of the way with PittMoss. You want it full enough that when you put your seedling on top, just the very top leaves of the seedling are just barely peeking over the top rim of the container. Water the PittMoss until it starts to drain out of the hole(s) at the bottom.

Add more of the mixture around the seedling so that the PittMoss in the pot is level everywhere and water again. The reason they are planted so low in the container is to help them build good root systems. About four weeks after germination, about two weeks after potting up seedlings the first time, you can pot the plants up again to about a 10-gallon pot but this is not necessary.

Typically, every 2 weeks the seedlings would need to be fertilized. But, by using PittMoss Performance, which has an added CRF (Controlled Release Fertilizer) it is a ready-to-grow potting mix, and therefore there is no need for extra fertilizing, so this is a step you can skip. Don’t forget to turn your plants frequently so each side gets adequate sun and fruit production is even and continue to water every other day.

  1. Step 5 — Stake the plants. Since tomato plants have no natural way to hold themselves up, if left alone, they will vine along the ground, so they need staking for support. A wooden post works best, just make sure you don’t use chemically treated wood for stakes, since chemicals will run off into the soil. Wooden stakes should be at least 1” square to provide adequate support. Rope ties work best cut about 18–24 inches long.

Insert stake into the ground about 3–6 inches from the base of the tomato seedling, just after planting (to prevent root damage) or right after flowering occurs. Place the stake on the north side of plant so the stake will not shade the tomato. The stake should extend at least four feet high above the soil surface. Wait to tie plants to stakes until first flowers appear. This encourages the main stem to grow strong.

Tie branches to the stake for support. Use a piece of rope and loop the tie from the stake, around the stem or extended branch, and back to the stake. Tie in a square knot to secure. Make sure the tie allows some “give” room for the plant so branches can get larger as the season progresses. Tie branches to the stake opposite blossoms so that when fruit grows, it is not trapped between the stake and the tie. Make sure you check plants regularly — even daily — for new growth. Continue to tie center stem and branches every 18–24 inches.

  1. Step 6 — Pollinate your plants. Since these tomato plants are being grown indoors, there is the absence of pollinating insects, so hand pollinating is a good idea. All you have to do is tap the stems lightly when flowers bloom to spread the pollen. You can also use a Q-tip and put it into each flower to speed things up.
  2. 7. Step 7 — Prune your plants. Indoors, you should prune early and often. Pruning promotes healthy plant growth and, by improving air circulation, discourages plant diseases. One way to know when it is time to start pruning is to wait for the stems and leaves below the first set of flowers to turn yellow. When you notice this color change, you can start pruning. Make sure you check for suckers. Look for the tiny new branches sprouting in the spot where a branch meets the stem on an indeterminate plant. These are called “suckers” and they are what you want to remove. Suckers left to grow will take energy from the rest of the plant and cause the plant to bear fewer fruits. This isn’t always a bad thing, but strategically removing suckers will help your plant bear large fruit all season long. To remove a sucker, grab a growing tip by the base between the thumb and forefinger and bend it back and forth until it snaps cleanly. This should ideally be done when the shoot is young and supple. Be sure to remove yellow leaves. Yellow leaves are leaves that use up more sugar than they produce. As the plant begins to mature, the lower leaves will naturally begin to yellow and wilt. This is perfectly normal, so pull these from the plant when they appear. It will keep the plant fresh and help ward off disease.
  3. Harvest your plant. Tomato plants produce fruit in 60–80 days beginning from the time the plant started flowering. Pick tomatoes when the color is full and size is reached (this varies depending on variety). Support the vine or stem in one hand and lift and gently twist the fruit away from the vine with the other. Ripe tomatoes should be firm but not too soft or too hard. Green tomatoes can be harvested and ripened indoors on the counter. Green, unripe tomatoes can also be fried or pickled. Ripe tomatoes will keep in the refrigerator for up to one week. Tomatoes also can be frozen, canned, or dried whole or sliced and can be made into juice, paste, relish, or pickles.

Written by Laura Noro

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