Growing Tomatoes Indoors (Is It Worth It?)
In the winter, the average supermarket tomato is shipped about 1,500 miles from the warmer climate in which it’s grown. To ensure it survives the journey, this tomato — along with many others just like it — is harvested while still green, and it ripens during transit.
The result? A bland, watery tomato that comes at a premium price because it was grown out of season and shipped across the country.
So it’s no surprise that when many people learn about indoor gardening, one of the first crops they think to grow is the tomato. Plump, vibrant, flavorful tomatoes fresh off the vine in December — that sounds pretty amazing.
But if you’ve done much research (or experimentation), you may know that fruiting crops don’t always fair well indoors, certainly not as well as herbs and leafy greens. That said, if you’re determined — and up for a challenge — that mythical winter tomato is possible.
In this post, you’ll discover the three keys to successfully growing productive fruiting crops indoors.
Disclaimer: This is hard.
Even if you do everything correctly, it’s unlikely that your fruiting crops will be as productive inside as they would be outside. Mother Nature has had eons to perfect her approach. We’re still catching up.
If you’re willing to invest time and money — and can tolerate a little frustration — you may enjoy a humble winter harvest. But I want you to know up front, results are not guaranteed. So proceed at your own risk.
1. Pick suitable plants.
Listen: if you try to grow a vining cucumber plant indoors, you’re likely setting yourself up for failure from the start. Most homes simply cannot accommodate the crop’s invasive, sprawling growth habits.
To save yourself from headaches like this, carefully evaluate the traits of the plants you want to grow. Then select only those that your indoor environment can support.
Size is important. (Pro tip: many fruiting plants come in dwarf or mini varieties!) But it’s not the only factor you should consider.
Here are a few general guidelines for picking fruiting crop varieties.
Indoors, you should stick to compact plants, such as mini peppers or dwarf tomatoes.
The first fruiting crop I tried growing indoors was green beans. And considering I didn’t know much about what I was doing at the time, they grew relatively well. A single plant yielded a handful of pods every few days.
Bush beans — which, as you might expect, grow in a bush-like fashion — are the best type to grow indoors. Pole beans, the vining type, are much more unwieldy. (Read more about bush and pole beans here.)
Peas tend to grow well indoors, too. But bush pea varieties are really just tame vines. So if you want to grow them, be prepared to deal with that.
I tried growing my own peppers indoors once. But they weren’t small varieties, and they grew beyond my grow lights. Ultimately, I had to transplant them outside.
Fortunately, many hot (and some sweet) chili varieties grow in a compact fashion. Once you find the right variety, be sure to review these tips on growing peppers.
Strawberries don’t take up much room. This trait alone makes them well suited for indoor environments.
There are a few different kinds of strawberries you can grow. (Read about the types here.) But I can personally vouch for the small, super sweet alpine strawberries. These seem to be a favorite for other Tower Gardeners, too.
Tomatoes are either determinate, which means they grow to a certain point and stop, or indeterminate, which means they grow in a vining fashion, expanding indefinitely.
Knowing this information, you might assume determinate tomatoes are best for indoor environments — where space is limited. Initially, I thought the same (which led me to try the dwarf determinate variety Tiny Tim indoors).
But there’s a catch with determinate varieties. Once they reach their full, mature stage, they usually produce one big round of tomatoes — which all ripen at once — and then stop producing.
Indeterminate varieties, on the other hand, will keep producing for you all winter long. But they also require a lot more attention — you’ll need to do some serious pruning. (More on that to come.)
Regardless of which type of tomato you grow, I recommend sticking with varieties that yield smaller fruit (e.g., cherry tomatoes). Beefsteak and other big slicing varieties are more challenging indoors.
You can find more info about growing tomatoes here.
Technically, there are bush varieties of squash and cucumbers, bred specifically for indoor growing. But I think they get way too big and cumbersome indoors. So proceed with these crops at your own risk.
2. Use (the right) lights.
Plants need a lot of light. That’s the reality for any food crop, but it’s doubly true when it comes to fruiting plants. Without adequate light, they simply will not yield flowers or fruit. That’s why successful indoor gardeners use grow lights.
Wondering if you really need grow lights? Thinking a large window might suffice?
If you have a big south- or west-facing window and are willing to turn your garden daily, that’s great. Your plants will love it. But you’ll likely still need grow lights for maximum productivity.
With that in mind, here are a few guidelines for choosing the right ones.
T5 fluorescent bulbs are the most cost-effective lighting option for the average indoor grower.
Grow light type
I wrote about grow lights two years ago. And my opinion now is as it was then: For the average home gardener, T5 fluorescent lights cannot be beaten.
Other common options include high-intensity discharge (HID) and light-emitting diode (LED) lights. Both of these cost significantly more than T5 fluorescent lights and aren’t really worth the investment unless you’re running a large-scale indoor operation.
Plus, in the case of HIDs, you’ll also need to buy ballasts, fixtures, fans, and other equipment. And the lights themselves produce a lot of heat, which can negatively impact plant growth, pose a fire risk, and even bleach fabric.
Within the world of fluorescent lights, you have a few options. T5, T8, and T12 bulbs are long and narrow — often referred to as “shop lights.” Of these, T5s (the bulbs that come with the Tower Garden Grow Lights Kit) are by far the most efficient and powerful.
You can also use compact fluorescent lights (CFLs) for spotlighting specific plants.
Regardless of what type of grow lights you use (*cough* T5 fluorescent *cough*), the light color temperature also matters.
Grow lights are generally divided into two groups: cool-colored, which is considered blue, and warm-colored, which is considered red. These light colors are measured in Kelvin (k) units — a theoretical measurement of temperature.
Cool-colored (~6500k) lights are good for compact vegetative growth, but not ideal for convincing plants to flower. Warm-colored lights (~2700k) are the opposite — great if you want to encourage your plants to flower and set fruit, but not the best for leafy growth.
Note: You should be able to find a bulb’s color temperature listed on its package.
If you’re reading carefully, you may have guessed that fruiting crops need red light. And that’s correct. But here’s an interesting detail: They also need blue light.
In fact, all plants need both red and blue light.
So it’s best to use a combination of cool-colored and warm-colored lights. If you’re using the Tower Garden Grow Lights Kit and want to grow fruiting crops, Joe Daugirdas suggested a clever idea over on Tower Talk:
Replace two of the bulbs included with the kit (which are 6,500k) with warm-colored (~3,000k) T5 fluorescent bulbs, which you should be able to find on Amazon.com or possibly at a local garden store. Then, simply alternate the bulbs: blue, red, blue, red.
This configuration should encourage balanced growth for all your plants and, when the time is right, induce flowering in your fruiting varieties.
If you don’t want to change out the bulbs in your Grow Lights Kit, you can alternatively spotlight the fruiting crops with a warm-colored CFL when you’re ready to initiate flowering.
3. Tend to your garden.
After you have picked the right plants and are using the best lights, your indoor garden should flourish. All that’s left for you to do is a little routine maintenance.
Fruiting crops require a little more attention indoors.
Use a fan
Aiming a small fan at your Tower Garden will help improve airflow around your plants, reducing the risk of mildew, leaf fungi, and other plant problems. It may also facilitate pollination (but you’ll probably still need to help with that).
Indoors, you should prune early and often. Pruning promotes healthy plant growth and, by improving air circulation, discourages plant diseases.
But most importantly, pruning prevents your more enthusiastic growers (e.g., tomatoes, peas) from overtaking your indoor space or extending past the range of your grow lights. Speaking of which, be sure to cut your plants back from the grow lights — leaves that touch the bulbs will burn.
You can find more detailed pruning instructions here.
Growing fruiting crops indoors is more tedious and time-consuming than growing them outside, largely because of pollination. Since your home (hopefully!) doesn’t have many bees buzzing around inside, you must play the pollinator if you want to actually harvest anything.
Hand-pollination is pretty straightforward. (But here are some tips just in case.) Most of the fruiting plants you might grow indoors are self-fertile — meaning a single flower contains all the necessary parts to produce fruit. So all you really need to do is shake those parts up.
The easiest, fastest way to do this is with the help of an electric toothbrush (ideally one you haven’t cleaned your teeth with). Simply activate the toothbrush, and vibrate the back of each flower for a few seconds.
If you don’t have an electric toothbrush, a cotton swab or small paintbrush will work — just touch the inside of each flower to move the pollen around.
For best results, hand-pollinate open flowers daily. If you have kids, consider letting them “be the bee” — it’s an easy task that makes for an engaging learning experience!
We covered a lot of ground! If you have any questions, leave a comment below or browse the following indoor gardening materials:
- The Ultimate Guide to Indoor Gardening
- 21 Plants That Flourish Indoors
- How to Ensure Your Indoor Garden Is a Success
- Tower Garden Grow Lights Kit
Otherwise, happy (indoor) growing!
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