Planting Rhizomes and Tubers

With the overwhelming feeling that we’re soon to exit winter, we begin to contemplate what will make a grand entrance into the spring garden. On top of the list are rhizomes and tubers, that give us the first planting opportunity of the encroaching season. While they now lie in their dormant state, they will soon unleash their growing energy and provide the first true signs of spring growth. So it’s worth reviewing how best to plant and then harvest these varieties.

Rhizomes Asparagus, Ginger, Turmeric, Galangal, Horseradish, Rhubarb, Hops, Mint (yes, mint!)

Plants like ginger, asparagus and rhubarb are best grown from rhizomes. which are technically underground stem systems. They invade areas around the parent plant to extend horizontally and produce above ground shoots, in this way, new “clone” plants are created. In the case of ginger and turmeric, we eat the underground rhizome itself (though the tops are edible too), whereas the above ground shoots are what interest us when it comes to asparagus and rhubarb. With hops - another famous rhizome - its flower cone is the object of our desire.

Rhizomes are often called “creeping rootstalks” and by dividing them it is possible to grow new plants from each piece. In nature, a rhizomes are known to survive fire and drought, laying dormant underground until good growing conditions are available. As a result, they are very hearty and can be transported easily without water or soil. Many people order seed rhizomes online or buy them from a local nursery to ensure that they don’t contain any disease/pesticides/herbicides. However, it is also possible to plant a piece of (organic) ginger from the grocery store- but success will vary.

It may surprise you but mint is also a form of rhizome and can be easily planted from reserved root stock; perhaps even from your flailing pot bound mint.

How to plant:

1. Soak rhizome for a few hours in water or compost tea.

2. In well draining soil, dig a shallow hole or trench and plant rhizome horizontally with any shoots or pointing upward.

3. Cover rhizome with about 3cm of soil.

4. Water in thoroughly. Continue to water every second or third day, as overwatering can cause rot.

Edible rhizomes are slow growing at first, so don’t expect any visible growth for about a month.

Harvesting

Rhizomes are typically long term investments and will grow in size, and therefore productivity, with age. Asparagus is, indeed one of these long term investments, particularly in a small space garden, but that’s not to say it isn’t worth your effort and a piece of your precious real estate. Rather than the traditional wait for mature asparagus to begin shooting, we now favour taking whatever we can get. The finer, adolescent shoots, while being less substantial offer unparalleled culinary prowess. 

Rhubarb plants will produce for around 10 years, but every few years the stems will become visibly crowded and thin, necessitating that you divide the root bulb (best to do this in late autumn). Regift your divided rhubarb to become the most popular gardener on the block or to expand you personal rhubarb empire.

Tubers Potato, Sweet potato, Yam, Cassava, Jerusalem artichoke

“It’s not a tuber!” shouted Arnold Schwarzenegger in the perennial classic Kindergarten Cop. At least that’s what we heard. Potatoes, on the other hand, are tubers. As are yams and the poorly named Jerusalem artichoke.

Tubers are neither roots nor rhizomes, but are often found in their company and are, in fact, a growth of reserve nutrients. Like an underground doomsday bunker, tubers store plant energy for an uncertain future. They are rich in simple carbohydrates (starches) and sugars, which is what makes them so delicious. It is this stored energy that gives them the potential to grow a new plant at a moment’s notice or lay dormant until conditions improve.

Anyone that has left a potato long enough has seen it start to produce sprouts. Seed tubers from a nursery are often well sprouted and will not carry any soil borne disease, which is not the case for market bought varieties. For those with small spaces, we recommend planting tubers in a felt pot or other container so that growth cannot invade the rest of your garden. Keeping tubers in a separate container also guarantees that you won’t miss any produce when it comes to harvest time.

How to plant:

1. Select a collection of your favourite seed tubers.

2. Larger pieces can be cut in half, but make sure that there are a few sprouting eyelits on each piece.

3. Dig a 15 cm trench in nutrient rich and well draining soil, space seeds about 25cm apart.

4. Cover over with soil and water in

Growing

We want to impart some potato wisdom so you don't become a Dud Spud Grower this season. When buying seed potatoes there's two paths/families that your potato will belong to. Don't worry, it's not a Montague and Capulet, we'll support whichever path you choose. This will determine how you grow your potatoes so pay attention... 

Determinant or short-season potatoes can be covered only once, when planted. These tubers will be ready to harvest once the plants have grown and begun to yellow and die back; in about 70-100 days.

Indeterminant varieties will yield a bigger, albeit later harvest (between 110-140 days). The plants that grow from these varieties can be repeatedly 'earthed' or 'hilled' - the process of covering over with more compost/soil - to increase the yield (three cycles is maximum). Each time the shoots are covered, a new level of tubers will form, meaning that upon harvest each layer will produce potatoes of varying maturity.

Harvesting

Tubers grown in the garden bed are best harvested with a garden fork, which lifts away much of the plant while allowing excess soil to fall through its tines. When harvesting, sink the fork into the ground - giving a fairly wide berth from where you expect the first tuber (don’t want to spear it!) - to lift the earth and reveal the tubers growing beneath.

When planting in a felt pot or other container, it can simply be dumped upside down to reveal all of the contents inside. This allows growers to quickly sift through the soil with their hands and ensures that no tubers will be missed.

Once harvested leave dirt on them and store in a cool, dark place. Decent ventilation is important because tubers will continue to breath and repair bruises/blemishes for a couple of months after harvesting. Keep away from sunlight.