Indoor Vegetable Growing

Many people grow pot plants on their windowsills, and they are almost always flower plants, so why not edible vegetable plants ?
There could be a number of reasons why growing vegetables indoors might seem attractive, but the two most obvious are; growing early crops when it’s far too cold outside, or you simply don’t have anywhere outside to grow any.

Growing herbs on your kitchen windowsill is probably the easy first step, so much so that it has become the fashionable thing to do. Several different herbs are readily available in shops and supermarkets nowadays, potted up and ready to be snipped and used. If you have bought one of these “instant” herb gardens and kept it alive for at least a few weeks, then you must be a prime candidate to become an indoor gardener and could very easily expand to include herbs that are not available in the shops.
If you haven’t bought a potted herb but like the idea of indoor vegetable gardening, then buying one is a good first step. Put it on a windowsill, master the art of watering it (see later) and see if you like the idea of becoming self sufficient … well in herbs at least.

The next step could be to grow some different herbs or maybe some different edible plants altogether. You will need a packet of seed and a small bag of potting compost from your local garden centre and something to grow it in. For a pot, it could be the suitably washed pot your now dead earlier herb was in, or maybe an empty yoghurt pot.
Any pot must have a few holes in the bottom, big enough to allow water to drain, but small enough so that the potting compost stays in the pot, somewhere between 5 mm and 10 mm holes are ideal. Almost fill the pot with compost and gently firm with your fingers or something slightly smaller in diameter than the pot, then sow a small quantity of seed, no more than eight or ten seeds, and cover with about 10 mm of compost. Stand the pot in a saucer and keep adding water to the saucer until it will absorb no more and then empty the excess in the saucer.
If you have a clear plastic top (from a yoghurt container) you could put that on the top, otherwise put pot and saucer on your windowsill and wait for you herb seedlings to appear, taking any top off immediately you see green shoots.
It will need watering from time to time and the way to do that is to pick the pot up and feel the weight. If it feels heavy it doesn’t need water, if it feels light it does. As before water the saucer, not the top, and throw away any excess water when no more has been absorbed after 10 minutes or so. Most plants hate to be waterlogged and if you continuously leave water in the saucer your plant will die.
For varieties, I wouldn’t recommend parsley purely because takes a very long time to germinate, but there are many different flavours of Basil to try and Summer Savoury is another that you probably won’t find in shops. Other fairly easy ones are Mint, Chives and Coriander.

Once you’ve mastered the skill of not killing your plants and/or want to grow something a bit more stomach filling than a pinch or two of herbs, then there are several vegetables that grow quite happily indoors.
When to sow is dependent on what you want to grow and the conditions you have to grow them in. If you have a heated room with a bright windowsill then you have the right conditions for early crops, but if you have an unheated room you can still grow crops later in the spring and summer which might be useful especially if you have nowhere else to grow them.
Vegetables that I have successfully grown indoors include; Carrots, French beans, Lettuce, Spring Onions, Peas, Peppers, Radishes and Tomatoes, plus Strawberries. The thing to remember when choosing what to grow is to look at the varieties that are either naturally dwarf or is a variety that has been bred for container growing. For instance, you could grow climbing French beans indoors, but it might prove to be a handful training 3 metre vines up to your ceiling, so it would probably be best to choose the bush varieties that stays a more manageable 40 cm tall. Also when choosing what to grow bear in mind that any flowering vegetables won’t get pollinated by bees in your living room, so even though there are dwarf varieties of Runner Beans, they need pollinating so stick to French Beans that do not.

・ Carrots
These can be grown for an early crop or at any time just for succulent young roots. Sown in a bucket means that they can be sown in mid-winter and kept indoors and then moved outside when the weather warms up in the spring or can be grown totally indoors as well. If you choose to grow in a bucket though, make sure you don’t over water unless the bucket has holes in the bottom. They also do well in troughs on a cooler windowsill providing you choose the shorter stump rooted varieties, Early Nantes, Chantenay, Mokum or the ball type for instance in troughs, plus the longer Amsterdam Forcing for buckets.
I would use a 50/50 mix of garden soil and compost, but if you don’t have access to garden soil then use all bought compost, the cheaper the better. Fertilizing soil for carrots is suppose to lead to forked roots, but I’ve grown them in pure new compost and never had that problem. You can sow fairly thickly, aim to have the seeds roughly about 20 cm apart. From a winter sowing you can expect to have reasonable sized roots by mid to late spring.

・ French beans
This is a very worth while vegetable to grow early indoors, so much so I’m surprised it’s not more popular. Grown in troughs on a sunny windowsill or a less sunny one for later in the spring, they will quickly produce tender pods for salads or as a cooked vegetable. Depending on the trough(s) you have chosen or have room for, sow one seed every 10 cm in a line up the middle of the trough. They germinate quickly with the warmth of a heated room and will soon grow into nice bushy plants that will flower and could be producing a crop of pods by February or March if sown in mid-winter. In an unheated frost free room they will be slower growing of course, but would be an ideal spot for sowing in early spring for April – June cropping.

・ Peas
Similar to French beans, these can be usefully grown indoors either for an early crop as well as later. If you like fresh peas and have no garden there is no reason why they can’t be grown in succession for an almost continuous crop.
Choose from the new very dwarf varieties like Twinkle or Avola, or the slightly taller Little Marvel.
These can all be sown in mid-winter despite what it says on the seed packet, for early crops or later for conventional cropping. Peas don’t like too much heat so later crops when the sun is stronger would prefer a bright but not sunny windowsill. As with beans sow in a trough, but can be sown closer, about 40 cm apart in a double staggered row, then they support one another although a few twiggy sticks would be useful for supporting Little Marvel.

・ Lettuce
“Cut and come again” loose leaf varieties are very easy to grow and can be treated like herbs. Sow in a shallow wide pot and place in a light spot and you will quickly have leaves to harvest.
For hearted lettuce I would choose small upright varieties like Little Gem or the new Iceberg Gem cross Elyburg, although I’ve yet to grow that one. Upright growing Cos type are best because lettuce leaves can quickly rot if they lay on the soil surface or lay on top of it’s neighbour, especially when growing conditions are not ideal.
Lettuces can be grown singly in pots or several to a trough. Sow seeds in situ and keep cool until germinated, not on a sunny windowsill, although they will need moving to a warmer sunnier spot after shoots start to appear. Bear in mind that lettuce won’t germinate if the soil temperature is above about 20 degrees, but will happily grow at that temperature and above once they have germinated.

・ Radish
Dead easy to grow, especially if you choose the fast growing Rougette. You can grow in shallow pots or troughs, sown fairly thickly about 30 cm apart each way and with Rougette you will have sizeable roots in less than 2 months.

・ Spring (salad) Onions
Use the same technique as the radishes except they take a little longer to achieve sizeable roots. They don’t require a great deal of heat and can be grown all year in a cooler room. Just about any variety will be fine, although there are now varieties bred for container growing that would possibly be a better choice.

・ Peppers and Tomatoes
Both chilli and sweet peppers can be grown in pots, although I must admit that I’ve never grown chilli peppers anywhere as I don’t like them. Tomatoes and peppers can be treated exactly the same, so all the instructions are for both. I wouldn’t grow either of them too early because they really need warmer growing conditions and while the vegetables above wouldn’t mind the occasional drop in temperature behind the curtains in winter, peppers and tomatoes would not be happy at all. But if you would like to grow early peppers or tomatoes be sure to move the pots into the room on winter nights. Sowing and growing are fairly straightforward, sow individual seeds in small pots (50 cm or yoghurt pots) and place in a warm spot, and airing cupboard is ideal … BUT check every day for shoots, as they need taking out into the light as soon as they appear. After a few weeks, when you see a few roots growing out of the drainage holes in the pots, carefully re-pot into larger ones until you get to the final pot size of about 170 cm. When they flower and the petals start to drop, wait until you see the small fruits start to grow bigger, then add a liquid tomato fertiliser to the water. I mix the recommended amount in an empty 2 litre milk container and use for every watering after that.
Choose the shorter growing varieties of both peppers and tomatoes that are recommended for container growing, although I would steer away from the drooping tomato varieties bred for hanging baskets.

・ Strawberries
OK, I must admit that strawberries are fruit and not a vegetable (but then so are tomatoes and peppers if you want to be factually correct). Strawberries grow very well indoors, and you will certainly get fruit before the local ones are available in the shops. There are two types of strawberry plants, ordinary and ever-bearing. Ordinary plants produce a flush of fruit for about a month to six weeks and then stop, ever-bearing ones just keep on fruiting until they give up in the autumn.
It’s up to you which sort you choose, they both have the same requirements, although you just might get fed up with a continuous supply of ever-bearing ones, not enough at any one time for jam making, can’t really successfully freeze them, but will still need picking every other day for maybe 6 months.
Whichever you choose, buy the plants (seeds are difficult and it will take a year) and plant in a trough about 20cm apart. Water well and if watering from the top make sure not to wet the fruit, or they might rot. Also make sure that any fruit doesn’t touch the window glass for the same reason.
Strawberry flowers are mostly self fertile, but hand fertilising reduces the likelihood of misshapen fruit. Use a soft artist type paint brush and brush each open flower in turn to transfer the pollen. When the fruit starts to show, feed with general purpose fertiliser once a week.

At times your plants will probably produce “runners”. These are long shoots with no flowers that will eventually have a small plant on the end. They are best cut off to preserve the vigour of the plants and to keep your windowsill tidy, but you can also produce new plants from them. If you want to increase, or replace your plants, fill a small pot with compost and peg the little plant down so that it is in contact with the moist compost. After a few days you will see roots growing and after a few weeks when your new plant is growing strongly, you can sever the runner at both ends and grow your new plant to full size.

A word on troughs, there are 2 types of trough available, one just like a flower pot with drainage holes and one with the drainage hole extensions that will leave a reservoir of water about 25 cm in the bottom and only drain above that.

Both are fine except you can’t water the reservoir type from the bottom, only from the top, although you still need it’s matching saucer to keep you windowsill clean if you happen to overwater past it’s 25 cm limit.
The other type is just fine for watering both from the top or bottom, although I would always recommend watering from the bottom.

Feeding, don’t feed radishes or lettuce at all, there will be enough fertiliser in the compost already. French beans and peas should also be OK, but with French beans in particular, if you see the older leaves turning yellow a dose of general purpose liquid fertiliser wouldn’t do any harm. Onions might need a general purpose liquid fertiliser after they have been growing for 2 or 3 months, especially if you want the bigger salad onions that you see in shops.
Tomatoes and peppers, as already advised, should be fed with tomato fertiliser at every watering after the first fruit appears, this is because these two plants will be living in the pots for a lot longer that the others and will have used up the added fertiliser in the compost when they need it most.
Always dilute liquid fertiliser as per the instructions on the bottle.

Yields, even if you have large empty windowsills it’s unlikely you will be self sufficient in vegetables, but it is fun to do and very, very satisfying to prepare a meal with some of your own produce.
A trough of 4 or 5 French beans will produce enough pods for 2 – 3 servings at a time and repeat that for probably 4 more times. Peas would be broadly similar, you can plan on roughly 6 or 8 pods per plant with 8 or so peas in each pod, not all the pods would be ready at the same time though.

Radishes, onions, lettuce and carrots are pretty much obvious, you get one mature vegetable per seed.
If you have enough room to grow all of those, plus a few tomatoes, you could certainly have a totally home grown salad at least once a week for a month or two. A bonus of course is that all your produce will be 100% free from pesticides, plus you can use organic compost and organic fertiliser if that is important to you, as the production from seed to plate is totally in your hands.

Good luck if you decide to have a go at growing something new on your windowsill, and if there is something you need help with, please don’t hesitate to ask over on the forum, joining if necessary.

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