All Green is open and so is gardening! Read about our Christmas Trading Hours here.

How to start an indoor herb garden

Garden advice
How to start an indoor herb garden
All Green
All Green
November 8, 2021
minute read

Everything you need to grow thriving, luscious herbs

Starting your own indoor herb garden is not necessarily an easy hobby, but it is a rewarding one. Herbs can be particular, and require attention and patience. But once you’ve picked your first batch, and tasted the fresh flavours of your own efforts, you’ll know that the reward was well worth the effort.

In this guide, we’ll teach you everything you need to know to grow a flourishing indoor herb garden. Once you’ve got the knowledge, have a look at our range of herbs, either online or in store, and pick your favourites.

1. Picking the perfect pot

Herbs can be grown in practically any container, if you’re willing to make a few modifications here and there. But you want to give your new herb garden the best chance to survive and thrive, so you need to be mindful of what’s most important. Here are our key considerations:

  • What material should your herb pot be made of? In order to choose the right kind of pot for your herb garden, you must consider your indoor humidity levels. Herbs are sticklers for humidity. Ceramic is impermeable: it doesn’t absorb water and let it evaporate. If you live in a dry or hot environment, ceramic pots would be ideal. On the other hand, porous terracotta pots are better for humid climates, since they let excess moisture out. Plastic pots are both common and affordable and, like ceramic, hold water well — but they do warp  in the hot sun, which may be of concern to you.
  • How big should a herb pot be? Herbs should be planted in a pot of at least 15 centimetres, if you’re planting one herb per pot. The roots of the herb will need space to grow deep and strong. Once you’ve decided on the herbs you’d like to grow, we recommend speaking to one of our experts for advice on your herbs’ specific needs.
  • How much drainage does a herb pot need? Herbs cannot be kept in standing water, so having adequate drainage is vital for their survival. If you find that your pots drain too quickly, add a layer of rocks or pebbles beneath the soil. Always remember to place your pots on top of a saucer or tray to prevent draining water from staining your sills and counters.

2. Potting mix or soil?

Herbs need potting mix, not soil. Confusing the two for each other is a common beginner’s mistake. Potting mix is usually a mixture of peat, pulverised bark and either perlite or vermiculite; those last two ingredients are aerators to help with drainage. Remember to check the packaging of your potting mix — it will usually tell you if it’s suitable for indoor potting. We’ve got a range of potting mixes that’ll be perfect for your herb garden.

3. Fertilising an indoor garden

You will need a fertiliser high in nitrogen, which promotes the growth of strong and healthy leaves. We recommend liquid seaweed or fish emulsion-based fertiliser: Seasol is a great fertiliser. How you fertilise your indoor herb garden depends on the season and temperature:

  • Summer: warmer weather promotes active herb growth, and you should fertilise your indoor herb garden once a week. 
  • Winter: in cooler weather when the sun doesn’t shine as much, you can reduce your fertilisation routine to once a month.
  • An alternative idea: many gardeners prefer to add liquid fertiliser to their herb garden every time they water it. To do this, dilute approximately ¼ of the prescribed quantity in the water poured into the herb pot. The reasoning here is that you are replacing the nutrients being washed away by the draining water.

4. Giving your herb garden adequate sunlight

Herbs love the sun, and need 6 to 8 hours of direct sunlight every day for optimal growth. You’ll need to consider which windows in which rooms are capable of delivering that level of sunlight to your herbs. We recommend placing your herb garden near Northern windows, which get the most sunlight down here in the Southern Hemisphere.

If you’re worried about consistent sunlight, either because you don’t have Northern windows or because of cloudy weather, there are solutions. You might consider investing in full-spectrum grow lights, which mimic sunlight. LED grow lights are perfectly calibrated for herb growth, and are also affordable and highly energy efficient.

5. The right temperature for for growing herbs

Herbs thrive in temperatures between 18ºC and 21ºC. Fortunately, that’s quite a comfortable temperature for people, too.

Of course, temperatures fluctuate well outside the ideal range during the day, and especially at night. But herbs are hardy enough to withstand that, though they must still be carefully monitored for health.

6. Giving your herbs just the right amount of water

Herbs do not need nearly as much water as many novice gardeners think they do. In fact, indoor herb gardens are commonly overwatered.

Here’s the trick to watering an indoor herb garden: you need the herb’s roots to grow deep and spread out. So, it’s best to let their pot dry out a little bit between waterings. The roots will grow down in search of water; they won’t bother if water is readily available at the surface. 

  • When to water herbs: wait for the surface soil to dry out — about two knuckles deep — and then water. 
  • How to water herbs: always in the sink, so that you can drain out excess water without damaging your sills and counters. Pour water in at the base of the herb, and pour till it flows out the bottom. You want the water moist, but not a sludgy mess. Wait till the water stops draining out of the bottom before you return the pot to its place. Never leave the standing water in your herb garden.

A little tip: if you spot yellowing in the leaves, that could be a sign of overwatering as much as of underwatering. If that’s the case, leave a little longer between waterings.

7. Herb health: how to check roots and pests

Making sure your roots are healthy is a simple process, and only needs to be done once or twice a year. You don’t want to disturb the herb too much, especially if there are multiple herbs planted together.

  • Lift the pot and check if the roots have grown through the bottom. If they have, the pot’s too small and the herb needs to be repotted. 
  • Remove it from the pot and gently break up the soil; the roots should be a healthy white and ready for repotting. 
  • If the roots are brown and tangled, they’ll need to be carefully trimmed before repotting.

Aphids are a common herb problem, but there is an easy solution for indoor gardens: simply rinse the herbs under strong running water in the sink. That should rinse the aphids off and down the drain.

If you notice little bumpy brown spots on your leaves, you might have a scale problem. Scale are actually insects, though they look like some sort of disease or burn. To get rid of scale, dip a cotton swab in rubbing alcohol and gently rub each insect. You’ll need to monitor your plants closely in the coming weeks to make sure you’ve killed them all.

A final note

The sight of a thriving indoor herb garden is always worth the time and effort that goes into it.

Just remember the most important thing: herbs are for eating. We’re not trying to be obvious — regularly cutting about a third of their leaves encourages herbs to grow thick and strong. Don’t feel guilty about giving your beautiful (and delicious) work a trim now and then.

Related articles

Powered by EngineRoom