Experimenting with Root Vegetables in Containers

I like eating root veg but I don't grow them much as some other vegetables, mainly because each plant can only be harvested once. Unlike runner beans or tomatoes, which you can pick over several weeks, even months.

Another reason I'm hesitant to grow some root veg is that I've rarely had consistent success with beetroot, radish or carrots. It remains a mystery to me why their roots sometimes swell up beautifully and sometimes don’t…. Is it to do with spacing, soil quality, sun, watering, pot size, feeding - or a perhaps a mix of all these?

In an attempt to learn more about them, I dedicated one of my growing ladders to root veg this year. 

I grew carrots, leeks, spring onions, beetroot, and radish in bucket sized pots. I started by sowing them close together, aiming for maximum yield. I then thinned them out as they grew.

Two weeks after sowing. The wire mesh is to keep out the blackbirds digging up the seedlings. Clockwise from top left: Tokyo long white bunching onions, radish, spring onions / scallions, beetroot, leek, carrot. 

Here's how they each did. 

Radish

Radish are often described as easy to grow, but many of us (including myself) struggle to grow them consistently in containers. Sometimes they swell up well, sometimes not.

Luckily, this sowing (variety Chioggia) did well. I thinned the plants out after a couple of weeks to leave about 1cm between them. Young radish leaves are edible and tasty, so we ate the thinnings, stir fried with lemon and garlic. Delicious.

The main crop was then harvested five to seven weeks after sowing. Here's one of the pickings: 

Radishes don't always plump up well in containers.... luckily these ones did ok.  

Radishes are fast to grow, often ready to eat in just three or weeks. The leaves are tasty, too. This makes them a great choice if you have an empty pot to fill for just a few weeks.

As I said before, the roots don't always plump up well - so don't be too hard on yourself if you just get a harvest of tasty leaves!  

Spring Onion / Scallions (variety ‘White Lisbon)

This was by far the most successful crop in the experiment, and has convinced me that spring onions / scallions are one of the most worthwhile and productive choices for small spaces. Furthermore, it seems they can be picked over many weeks without going tough or bitter (indeed, I still have some in the pot over 8 months later!). I wrote a separate post about growing these here.

One of many bunches of spring onions picked from the one bucket. Delicious freshly picked, too! 

Japanese bunching onions

Like the spring onions, these were happy to grow very closely spaced, probably only about 1/2 cm /  1/4 inch between plants. They grew strongly and even larger than the spring onions.

However, unlike the spring onions, I noticed they needed picking within a shorter time frame - or the leaves started to loose their colour. Still, they remain a highly productive and delicious crop - making them a good choice for our small container gardens.

The Japanese bunching onions, top left, grew strong and large - but started to lose vigour once they got to this size. So they need to be picked sooner - or perhaps grown in a larger pot with more space. 

Leeks

These did OK but were much slower to grow (the variety was Carentan). After reaching a certain size (about pencil thick), their growth stalled. I suspect they might have benefitted from more space (each plant was about 1cm / 1/2 inch apart, and then thinned to 2 cm / 1 inch) and a larger pot. The small leeks were tender and tasty to eat. However, overall, it didn’t seem like a great yield. I will continue to experiment by using a larger pot and giving each plant more space to see if it results in a better harvest.

Carrots

I don’t grow often grow carrots, mainly due to a lack of consistent success with them - and because they are so cheap to buy.  I chose the variety Parisian Paris Market for their short stubby roots and good flavour. 

I sowed them close (1/2cm / 1/4 inch between seeds), and then thinned to about 1cm apart. Unlike the spring onions, they didn’t appear to like this close spacing.  The harvest was tasty but the roots small, making them fiddly to deal with, and not giving much to eat.

An unsatisfying harvest of rather small carrots, probably because grown too close together. 

I then resowed the carrots in two more pots, giving the seeds more space (about 1.5cm / 3/4 inch between seeds) to see if this made much difference. I also grew some in new potting mix and some in old potting mix with added fertiliser. The greater spacing worked better and produced some decent sized carrots. Interestingly, they thrived better in the old potting mix than the new one. We may not be able to draw many conclusions from this, except that carrots can still grow well in old potting mix.

Giving each carrot more space resulted in slightly larger carrots. 

Beetroot

My strategy with beetroot is usually to sow close, and then thin out as they grow, leaving just six to ten plants in the pot to swell up. I use the thinnings for their leaves, which are tender and tasty (like an earthy spinach). However, as with radish and carrots, the degree to which the roots then plump up in my containers seems to be variable. Fortunately, this time, they performed reasonably well, despite the plants not looking particularly healthy (see leaves in the photo below).

Not a bad harvest from a bucket. But also quite a lot of effort to grow basically what is enough for just one meal. 

Conclusions

Success in gardening comes from trying and experimenting and learning as you go. I haven’t grown root crops as regularly as some others - and this small trial definitely helped my learning. Here are the main lessons - I'd love to hear your experience and learning in the comments. 

• Spring onions / scallions seem to grow well when sown close together and then thinned out as they grow. They are very productive when grown like this and can be harvested over a long period. This, coupled with how useful they are in the kitchen, has convinced me that I will want to grow lots of spring onions every year! 
• Bunching onions grow similarly well but need to be harvested over a shorter period when grown with close spacings in this way. 
• Radishes are quick to grow, productive but don't always plump up reliably. They also need to be picked in quite a short window of they can taste tough and bitter. 
• Leeks are slower to grow and probably benefit from more space and a larger pot.
• Carrots also seem to do better with more space.
• Beetroot are a bit slow, but can grow to a reasonable size in a bucket sized container. Fun and tasty, but not hugely productive relative to the space they take up.
  

What are your observations? 

How have you found growing carrots, radish, beetroot, leeks and spring onions / scallions in containers? Do they always plump us successfully or are they a bit hit and miss. Do you have any tips or insights to share from your experience that can help us grow them better? Or any varieties that you have found are particularly good for containers?