Growing Root Vegetables in Containers
Growing root vegetables in containers is not a particularly challenging task. Certainly no more challenging then growing any other vegetable in a container. My favorites are radishes, beets and carrots. They are all easy to grow and the best part is pulling them up to see how you did. There are several varieties of each of these vegetables and the best way to see this is to study a seed catalog. My favorite beets are Yellow and Chioggia and my favorite radishes are French Breakfast and Watermelon. Here are some things you should know before starting out.
Chioggia Beets nearing maturity in a sunny box by the railing of my balcony.
Chioggia Beets are striped inside with alternating layers of white and pink.
Don't underestimate the size of the roots. Take a carrot for example. A six inch carrot will have a few more inches or root below it that tapers deep into the soil. For things like beets, radish and short variety carrots you should use a container that is at least 8 inches deep. The last time I grew carrots I used a large storage tote. The container I like to grow beets in is 12 inches deep.
You should endeavor to provide your root vegetables with as much overhead light as possible. I haven't had any luck growing low lying root vegetables in the window sill or near the back of my balcony where all the sunlight enters from the side. But when the light was near overhead the plants remained low and spread out, resulting in roots that stayed in the ground.
I was able to plant quite a few carrots in this storage tote.
When root vegetables are under nourished or not provided with ample light they will have a tendency to grow tall and spindly. Their roots will extend out of the soil and not become bulbous. Sometimes when this happens you can gently push them further into the ground or perhaps pile some soil up around them to keep the roots buried. It works for me... sometimes.
These are vegetables that must be started from seed. They do not transplant well. Before planting any seed in your container, be sure the soil is thoroughly moist. After you seed the container you will only have to add enough water to dampen the seeds. If you heavily water the soil after planting your seeds, you'll end up either exposing the seeds, shifting them around or washing them further into the soil. You have to be gentle when watering a container with newly planted seeds.
Beets, carrots and radishes all need about 9 square inches to grow in. You can plant in rows but I prefer to use a grid or some other pattern the makes the best use of the surface area in the container, maintaining a 3 inch distance between plants. Pat the soil down evenly across the entire container and use your finger to make small impressions in the soil to a depth required by the type of seed you are planting.
Carrots are not very demanding when it comes to fertilizer but you must use a loose and light potting soil. One that is free of sticks and rocks. Carrots prefer something they can grow down into with ease. Beets and Radishes are best grown in rich soils and like as much fertilizer as you can give them. They are cold weather crops and taste better when grown in the spring and fall. To get them up to a good size within this cool weather window, keep them fertilized to promote rapid growth.
Small Snow White, Baby and Dragon carrots.
Carrot seeds are very small and should not be planted very deep: no more than 1/8 inch. Realistically though, that is just another way of saying just below the surface. I just make a slight indentation in the soil, drop a few seeds in and cover lightly with some potting soil. The seeds are so small that it will be hard to get just one seed in each hole but that's ok because seed packs of carrot seed tend to contain LOTS of seed. Once planted, very gently moisten the surface enough to soak the seed in the soil but not so much that the seed gets washed way. I find a spray bottle works well.
Carrots take on average 60 to 70 days to mature but don't be afraid to pick them early. In fact, the younger the better. Because they take so long to grow, it is a good idea to start out over planting your container and thinning them out as they grow. But don't over do it. The tops easily grow into a tangled mess making it harder to pull one without disrupting it's neighbour. If the crowns of the carrots become exposed to sunlight they will start to turn green and taste bitter. You can hill up the soil around them if this starts to happen, to reduce exposure.
Beet seeds come in clusters of six seeds which makes them much easier to handle. You can plant these a bit deeper: around a half inch. Some beets will come up fast and others seem to take forever. Soaking the seeds for a day will help get a head start on germination but don't bother soaking seeds if they are coated with a fungicide. Soil temperature will also play a significant factor in germination. Because the seeds come in clusters, you will have to pinch off all but one from the cluster that pops up unless you are growing them for baby greens in which case you can just eat them as they grow.
It takes about 50 days for a beet to reach maturity. When best to harvest them depends on what you want to do with them. If you are after the greens to use in salads, wait until the leaves are a few inches long and cut the outer leaves first, leaving the inner leaves to grow so the plant will keep growing and you can harvest more leaves later. You can pull up the root and eat it whenever you feel it's at the right size. But don't leave beats in the ground too long or they will taste tough and fibrous.
A pair or Watermelon Radishes I grew in a container next to some beets.
Some radish varieties grow as large as beets.
Radish seeds are big enough that you can manage to just plant one or two per hole. And they don't have the same space requirements as beets or carrots so go ahead and plant them closer together: as close as 1.5 inches instead of 3 unless you are planting a larger variety radish. Plant the seed to a depth of a quarter inch. Radish seed will come up fast and reach maturity within a few weeks. You can read more about my radish growing exploits on my Radish page.