Growing indoors is a great way to extend the herb garden all year. Even with an outdoor space, growing on your kitchen worktop or window sill, keeps the herbs at your fingertips and you will use them more often. Fresh is best!
As with all types of gardening it is important to make sure that the plant that you are trying to cultivate is happy in it’s environment. Herbs can be tolerant of different soil types but they do have various needs.
INDOOR HERB GROWING TIPS
Light is the most important aspect of growing indoor herbs, and many people don’t have enough. Most experts agree that six to eight hours of light per day is optimal.
Orientation: A southwestern-facing window is your best bet for good light.
If you can’t get light from the sun: Get a few clamp-on reflector lights with compact fluorescent bulbs, the lights should be placed very close to the plants, about four to six inches away. There are also light fixtures that mount under a kitchen cabinet if you want to have herbs on the counter. The bottom line is, no plant will thrive if you can’t give it enough light.
A few issues explained:
If you see brown spots on the foliage: That means the plants are getting too much light, but this is a rare scenario unless you are using grow lamps.
If the plants are growing longer stems and fewer leaves: They’re not getting enough light and are stretching to find more. Add supplemental light or move them to a place that receives more natural light.
When to water: It depends on your plants. The best thing to do is wait until the soil has dried out, which you can gauge by inserting your finger up to the knuckle into the soil as this allows you to feel the moisture at the roots. Keep an eye on them and then water when you feel that the roots are dry.
How to water: Put the plants in the sink and water from the top, just like nature. Water the base of the plant where the stem meets the dirt, not the leaves; let the water soak through. Then soak the plants again. Let them drain completely and put them back in their trays. You can water in the morning and let the plants drain while you’re at work. Never leave the plant standing water in the tray or you’ll run the risk of rotting the plant’s roots.
If the leaves are yellow: DO NOT immediately water. Most yellowing is due to over watering. Check that there is no stagnant water in the tray. Lift the plant and see if the roots are wet or dry. Reduce fertilization if the roots are dry as this may be the cause.
What material to use: Terra cotta, because it breathes. The saucer material is not as important, since its main purpose is to protect your counter or window sill. I personally don’t put stones in the bottom as I find they clog the roots.
The best size: Bigger is better. For individual herbs, the pots should be no smaller than 15cm diameter. To grow multiple herbs together, you’ll want to put two or three in a pot that is about 25cm in diameter and about 20cm deep.
High-quality organic potting soil with good drainage is a must, and it should be rich, loamy, and not compacted. You can add perlite (buy it at any garden store) to increase drainage; a ratio of 1 part perlite to 25 parts soil is good. Do use soil for indoor growing not just a shovel from the garden. Outdoor soil can contain diseases and may not haver the right nutrients available for growing indoors.
How to judge drainage: Roll some of the soil when wet in your fingers it should stick together but feel a little grainy to the touch.
Add eggshells: Mediterranean plants like rosemary, thyme, and basil do well with a little extra lime; you can use eggshells for this. Collect some organic egg shells, break them up and put a spoonful into each pot when you prep the soil for planting.
Herbs are fairly robust, but they still like to be fed a good organic fertilizer such as liquid seaweed. You’re growing herbs for their leaves, not their flowers, so find a fertilizer that doesn’t promote blooming. That means the fertilizer needs to have a low level of phosphorous.
Watch your plants : The plants will let you know if they need to be fed . If they seem to have stopped growing, they probably need food. If the plants are turning yellow and you’ve already ruled out watering issues, this may also mean they need feeding.
If you are a novice and would like to get quick results consider buying plant “plugs” (baby plants), not seeds—growing from seeds is harder and takes longer. When you’re buying plants to grow indoors, buy an herb that’s never been planted outside; changing the environment can be traumatic for the plant. Shop local and you will find plants that are acclimatised to your area.
Rotate them: Move your plants regularly so they benefit from all round sun.
Harvest with care: Cutting your herbs encourages growth. But don’t cut more than a third off.
Ventilation: Herbs need good air circulation as they are prone to fungal diseases such as powdery mildew. You can combat this by putting your pots on a large tray covered in pebbles so that air can circulate up through the drainage holes.
Pest inspection: If you see aphids, rinse them off in the sink. If you see scale (it looks like a brown, rusty spot on the underside of the leaf), wash it off with a mild soap or rub off each spot with a little bit of rubbing alcohol, and then rinse the plant.
Winter: Most herbs go through a rest period during the shorter days of winter due to the reduced light so be aware that they require no fertilisation and very little water during this period.
Repotting: Check potted herb perennials about once a year to be sure the roots aren’t growing out of the bottom of the pot. If they are, take the plant out of the pot and inspect the roots: They should be healthy and white, not brown and growing around in a circle. If the roots look bad, you have two options:
- Trim off a little bit and transfer the plant to a bigger pot.
- Or if you are happy with the size of your herb you can just cut around the roots vertically, about a 1.5cm to 3cm, and slice the same amount off the bottom. Repot with extra soil, and take off about the same amount of upper growth as you removed from the roots, to maintain a balance.