Useful Tips for How to Grow an Indoor Vegetable Garden

Grow your own food throughout the year with an indoor vegetable garden. Discover the best vegetables to grow indoors, how to grow food hydroponically or with potting mix, lighting, nutrient and water requirements, pest advice, and tools.

Growing your own food is something that we tend to think of as an outdoor pursuit. But what if the season is too cold or you don’t have much outdoor space to garden? Creating an indoor vegetable garden will allow you to grow food all year round, no matter where you live. It will not be restricted by season or availability of outside space, plus you could have fresh herbs or veg just a couple of steps away from your plate. Whether you have a windowsill, conservatory, or a dark apartment, it’s time to get sowing, growing, and enjoy all the benefits of homegrown fruit and veg.

It’s not as simple as migrating your outdoor gardening techniques inside the house though. Indoor gardening presents challenges that are less than an issue in your outdoor vegetable garden so you’ll need to think differently. There is the issue of how to pollinate fruit, knowing what grows well indoors, and how to grow them, and the cost of equipment and materials. This piece will give you useful tips for how to grow an indoor vegetable garden and guidance on what you can grow.

Ways to Grow an Indoor Vegetable Garden

Growing edible plants indoors can be simple and fun or complicated depending on what you choose to grow. You can sprout seeds in jars, grow microgreens in mini trays and cloches or try larger plants like tomatoes and chilis. You could also stick to more traditional methods of sowing seeds in pots, modules, or seed trays and just simply enjoy the wonder of watching them germinate indoors. There are also many easy-to-grow vegetables that will grow both indoors and in the garden.

You can grow an indoor vegetable garden in potting mix, much like you would do in an outdoor garden. If you are feeling more adventurous you can even grow food without any soil at all, hydroponically, by channeling water and nutrients directly to plant roots. I’ve also seen people set up small greenhouses indoors, and even grow rooms dedicated to providing the light and conditions that plants need.

Humidity is something that needs monitoring, both in the seedling stage and when mature. The air inside the home tends to be drier than outdoors so you can use plastic covers (propagators), misters, and other techniques to keep plants happy.

You’ll also need to keep an eye on lighting, potting mix moisture, and indoor pests. If your crops need pollinating, you might need to give them a hand. With no pollinators inside your house, some fruit flowers will need you to spread pollen from one flower to the next. It’s not that complicated since you can use a small artist’s paintbrush to brush pollen from one flower to the next.

Vegetables to Grow Indoors

Indoor growing isn’t suited for all vegetables but there are some that will do great! Ideally, prolific cropping petite plants are best so they take up minimal space. Chilies, microgreens, tomatoes, and greens such as salad leaves and spinach provide abundant harvests which can keep you gardening indoors all year round, even if the weather outside is not prime. And of course, a kitchen cannot be without herbs! See below for recommended varieties and how to look after your indoor vegetable garden.

Herbs	January-April is a great time to sow herbs, although you can grow them all year round. Rosemary mint, basil, chives, oregano, parsley can all be grown in pots on a windowsill. Sow in small batches for continuous crops and evergreen rosemary will just keep on going with little intervention.	Grow in a bright area. No feed is required. Many herbs are drought tolerant so weekly water should be enough but keep a careful eye on basil as that is far needier for water than the other herbs.
Microgreens	Microgreens are a healthy addition to salads and sandwiches since they are packed with nutrients. Grow in small pots or a propagator, any time of year. These fast-growing superfoods can be on your plate in two-three weeks. Try pea shoots, kale, basil ‘dark opal’ or rocket ‘Victoria.’	Mist or water from the base but do not keep too wet or roots may rot off. Go easy on the seed, do not overcrowd. Keep aerated. No feed is required as they mature so fast from the seed.
Sweet peppers	‘Mini Belle’ and ‘Mohawk’ are great compact varieties. Sow seeds from February-March in a propagator. The stem may need support as the plant matures.	Peppers love light and warmth. Water little and often and boost weekly with a high potash feed once flowers appear.
Lettuce	Cut and come again salad greens can be sown from February. Try rocket,  mizuna, lollo rosa, salad bowl, baby oakleaf, and compact butterhead Tom Thumb. Succession sowing in pots will ensure you always have a fresh crop. Sow seeds little and often.	Grow by a south-facing window for plenty of light but take care not to scorch leaves in summer. Lettuce is particularly suited to grow lights or hydroponics. Water twice a week to keep moist. Check it does not dry out. Feed every couple of weeks with a high nitrogen fertilizer to promote healthy green foliage.
Chilies	Chilies need a long growing season to achieve fruits, about six months from seed to maturity. Sow January – February. Larger plants may need support.  Varieties vary in heat strength. See the Scoville scale. Try mild pimento, banana pepper, medium jalapeños, Serrano, Numex Twilight, cayenne, apache, and compact Prairie Fire or scotch bonnet and habanero if your taste buds want to be tested!	Chilies like heat and humidity. Place by a good light source. Air can be kept moist by placing a water bowl on a nearby radiator. Chilies may require artificial light during winter. In hot weather, you may need to water two-three times a week, less in winter. Feed weekly with a high potash fertilizer.
Radishes	Sow in spring through to autumn in a deep container. Radishes are quick to mature so keep sowing little and often for a continuous crop. The green leaves are edible too. Thin seedlings. Grow ‘Caro,’ ‘Cherry Belle,’ ‘D’Avignon,’ or ‘Early French Breakfast.’	Place in a bright area with at least six-hour sunlight a day. Water two to three times a week, do not constantly soak or roots will rot, feed with an organic all-round fertilizer like seaweed every couple of weeks.
Tomatoes	Bush toms are compact for containers. Try dwarf ‘Tumbling Tom’ and ‘Tiny Tim’ or if more space available grow cherry tomatoes like ‘Sungold,’ ‘Sweet Million’ and ‘SuperSweet100.’ All good indoor croppers. Fruits are small and plentiful but the plants will need support as can grow to three-foot (one meter).	Grow by a south-facing window for maximum light. If growing through winter you may need artificial light to aid growth. Feed and water weekly with high potash formula to promote fruit growth. Organic seaweed is ideal. Better to give a good, long soak rather than multiply brief sprinkles.
Spinach	Grow spinach in a well-drained container with potting mix or hydroponically. Sow March-April. Try baby leaf sweet ‘Monnopa’, disease-resistant, slow to bolt ‘Toscane,’ exquisite ‘Rubino’ for colorful foliage, or perpetual spinach for larger, perennial plants.	Place in a bright spot but not direct sun. Keep watered but not wet to avoid root rot and fungal disease. Feed every two weeks with a nitrogen-based fertilizer, like nettle tea, to promote green leaves.
Citrus fruits	Dwarf citrus trees are excellent for indoor growing. Try dwarf lemons ‘Meyer’ or ‘Ponderosa,’ limes, tangerines, and nectarines. Best to buy root grafted dwarf trees.	Citrus trees like lots of light and cool roots so avoid dark pots, which absorb heat. Choose free-draining citrus potting compost to keep roots moist but not soggy and feed with a citrus fertilizer.

Indoor Gardening in Potting Mix

There are various challenges with growing vegetables indoors, and many of them have to do with what the roots grow in. For indoor gardens, buy quality peat-free potting mix and use perlite, vermiculite, or coir to help retain moisture, aerate the soil and improve drainage. You can use up to 33% of these additional materials.

Whatever you do, make sure to not use garden soil. Firstly, it compacts and dries out very quickly in containers. It will also contain fungi, weeds, diseases, and microorganisms, and possibly even worms. All of which will not be beneficial or necessary for an indoor vegetable garden. The downside of not using your own homemade compost is that you have to purchase a premade product, usually in a plastic bag, and remember to mind your back when lifting.

Growing Food Hydroponically

Hydroponic gardening involves growing plants without soil. Instead, water and nutrients are delivered directly to the plant’s roots supported in a growing medium such as rockwool or hydrocorn, vermiculite, perlite, or sand. On the whole, growing hydroponically can be advantageous.

First off, it’s a successful way to grow an indoor vegetable garden practically anywhere. Increased oxygen to roots promotes growth, yield, and health; and by delivering feed in liquid form, nutrients are quickly absorbed with minimal energy. This can produce healthy strong plants which are less prone to pests and diseases. Hydroponic gardening can be expensive and have an environmental impact, though. There’s also a big debate on whether it can even be considered organic.

Light Requirements for Indoor Vegetables

Germinating seeds in summer is easy. Pop your pot near a bright window or conservatory and your new seedlings will receive all the natural light they need. However, if you are starting seeds indoors in the winter, you may need to boost your plant’s daily expose to light with grow lights. There just is not enough daylight available during winter to ensure the plants can sufficiently photosynthesize to grow strong and healthy.

Grow lights will provide your plants with their lighting requirements but at a cost both financially and potentially with energy use. I know that my electricity bill goes up a bit when I’m starting seeds and seedlings indoors so that’s something to consider. The type of light you use makes a big difference though and fluorescent (CFLs) will be less efficient than light-emitting diodes (LEDs). There’s a little more information that you may find useful on this over here.

Nutrient Requirements for your Indoor Vegetable Garden

Like plants growing outdoors, the crops in your indoor vegetable garden will need nutrients. They include nitrogen, phosphorus, and potassium (NPK) as well as trace minerals. Outdoors, much of this comes from compost mulch that you apply to the soil, but it can also come from the soil itself. Though potting mix has a good mix of these nutrients initially, it depletes quickly, and you will often need to feed indoor crops. Some of them may have an odor though, so make sure that the ones you use don’t offend your senses.

Liquid seaweed is a great natural fertilizer all-rounder for the indoor vegetable garden but if you want to encourage leafy growth use homemade nettle tea and for fruits use potassium-rich comfrey tea in potting mix. You will usually feed plants by mixing granules into the potting mix or adding the liquid to water and using it in the watering regime. Feed every couple of weeks through the growing season, depending on the plants you’re growing. You do not need to feed as frequently as outdoor veg as nutrients are not leached away by rain.

Liquid fertilizers are preferable for indoor vegetable gardens and hydroponics. With the latter, there is less chance of pipes clogging up than with powdered or granular fertilizers. And rather than buying premade fertilizers, there is, of course, the option of making your own DIY organic fertilizers.

Watering Indoor Vegetables

Hydroponic systems should have their waters changed every couple of weeks. You can get some pretty troublesome issues with pot-grown indoor vegetable gardens if you don’t closely monitor their moisture levels and watering technique, though.

Because tap water contains additives that plants don’t respond well to, it’s best that you always water them with rainwater or filtered water. Avoid watering the top of the potting mix too. Instead, water plant pots from the base. That way the roots can draw up water directly from a saucer or tray.

You can also set the pots in a sink to first draw moisture up, and then by pulling the plug and leaving them in the sink, the excess moisture can drain out.

If you water the top of the potting mix it can, in time, rot the stem or wash away the soil and expose fine roots on the surface. If you’ve ever seen houseplants with shriveled or wilted leaves it could be due to root exposure damage. Watering from the top also creates a crust, which can be difficult for young seedlings to grow through. It’s not a big deal for larger plants, but something to think about if you’re germinating trays of seeds.

When it comes to watering, you also need to think about the moisture in the air. The humidity inside our homes is 40-60% less than what plants tend to thrive in and it can contribute to leaves wilting, yellowing, developing brown edges, and generally looking sick. One way to increase humidity around your plants is by misting them with a simple plant mister. Water evaporating from leaves creates a temporary change in humidity.

Dealing with Fungus Gnats

Fungus gnats are tiny dark flies with transparent wings, which can be found, on the surface of pots, and seed trays or flying around indoor plants. They bear an uncanny resemblance to tiny mosquitoes but don’t bite.

Fungus gnats thrive in damp compost and relish people who overwater their plants. They can be an utter pest in hydroponic systems too. Although the adults don’t particularly pose a direct problem with your plants or home, the larvae en masse can damage roots and hinder plant growth.

So how to avoid them or get rid of fungus gnats if they have set up residence in your home? You can sterilize your potting mix, don’t allow fungi to breed, or use a pebble mulch to deter female flies from laying eggs on the potting compost surface. Some people have success with popping chunks of raw potato in an infected pot because the larvae are drawn to the chunks and then can be removed. You can also hang up sticky traps to reduce the number of adult flies.

For biological control, you can apply Nematode Steinernema feltiae or bacteria Bacillus thuringiensis to destroy the fungus gnat larvae or apply a fungus gnat mulch top dressing to deter egg-laying.

Indoor Gardening Products and Kits

The gardening industry has recognized the growing desire for people who want to grow food in their houses. Sometimes the gadgets are a little expensive and perhaps unnecessary and sometimes they’re absolutely brilliant! Here are some that I found online:

• AeroGarden Harvest is a compact unit that facilitates growing herbs and vegetables all year round. It has the capacity to grow six plants at a time under a 20-watt LED lighting system so is both compact and productive.
• The Complete mason jar sprouting kit is a genius germination kit, which provides you with everything you need to sprout seeds in one space-saving device. It allows you to easily grow and harvest mung beans, alfalfa and broccoli, and other high nutrient microgreens.
• If you have the budget and are serious about creating a modern indoor vegetable garden, the Vertical hydroponic grow kit by Aerospring might be up your street. It can grow 27 plants at the same time so can keep you well-stocked in greens all year round.

Benefits of Growing an Indoor Vegetable Garden

Growing an indoor vegetable garden has tremendous benefits because it can keep you in homegrown veg regardless of outdoor space. It also ensures you can keep gardening throughout the cold winter months even when the soil outside is frozen.

Having herbs and vegetables in close proximity to the kitchen is always a win, but especially so if you can’t grow outdoors! Just snip off herbs and veg as you need them; ingredients do not get fresher. You could even try growing tropical crops like pineapple.

Indoor Gardening Inspiration

Now you are raring to set up your indoor vegetable garden, check out these useful ideas. They include additional reading about edible houseplants, toxic houseplants to avoid if you have pets and helpful tips to help you get the best out of growing your own veg.

• Houseplants that are Toxic to Cats
• Guide to Edible Houseplants
• How to Plant a Winter Vegetable Garden
• Don’t Make these Common Gardening Mistakes