How to grow rhubarb

Plant it, watch it grow. Well that was the easiest and shortest post ever! But seriously, while it’s widely known as the plant you can’t kill. There are still many things you can do to ensure you have the biggest and best rhubarb harvest. It is definitely a hardy plant, it’s right up there with mint and horseradish. So if you’re not known for your green thumb then this is a great plant to start with!

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What is rhubarb?

At this point you’re like….duh a fruit. Which is what I would have said too, but then we would have both been wrong. Rhubarb is actually a perennial vegetable (say what?) that people use as a fruit. Mind blown, am I right?

As long as you keep it healthy, these plants can be productive for as much as 10 years. Just make sure to resist the urge to harvest in the first year. This enables the plant to build up enough strength to be productive for many years to come. After the first year, feel free to harvest from April to June.

Is rhubarb poisonous?

Yes and no. The leaves are definitely poisonous as they contain Oxalic acid and anthraquinone glycosides. So you may be wondering what would happen if you eat rhubarb leaves. Well, if ingested the Oxalic acid can lead to many uncomfortable symptoms, including:

• Burning sensation in mouth and throat
• Difficulty breathing
• Diarrhea
• Nausea
• Pain in eyes
• Stomach pain
• Weakness
• Vomiting
• Red pee
• Kidney stones
• Seizures
• Coma

So do us all a favour and don’t eat the leaves, ok? This should be obvious at this point, but when harvesting rhubarb it is important to only use the stems.

If you do ingest the leaves (but you won’t because we already talked about this). Call a doctor or Poison Control immediately.  Don’t mess around with this stuff.

I don’t plant my rhubarb in the back yard as I have a dog (Bacon) and she’s not the brightest. So not wanting to take any risks, I planted my rhubarb along the side of the house (my grapes are there too cause they are poisonous to dogs too). I mean look at her face, it’s just not worth the risk!

So now that you are terrified about the leaves what should you do with them? The best thing to do is put them safely in your compost bin.

Rhubarb and animals

As I mentioned, I didn’t want those pesky rhubarb leaves anywhere near my dog Bacon, so I planted them at the side of the house. If you are lucky enough to have chickens on your homestead then make sure to keep them away from the leaves too. The leaves can hurt humans, dogs and chickens alike. So just make sure to keep you rhubarb away from anything that could potentially eat it, just to be safe.

Seed or plant?

Rhubarb can be grown from seed or as plants purchased from your local garden centre. If you decide to grow your rhubarb from seed, just keep in mind that it will take a year longer to produce stalks. My preference is to buy one-year-old plants, known as ‘crowns’, that have been divided from strong, disease-free plants.  Rhubarb grown from seeds may not have the intense red colour you would be expecting. But they will taste the same, which really is all that matters.

When to plant rhubarb

Planting crowns

Plant one-year rhubarb crowns in early spring as soon as the ground is workable, when the roots are still dormant and before growth begins or plants are just beginning to leaf out.  If you happen to miss the spring window, then don’t fret! Rhubarb can also be planted in the fall after dormancy has set in.

Planting seeds

There is more work involved if you grow from seed, so let’s take a quick look at what is involved. As with any seed, there is a “shell” surrounding the plant, which is there to protect it. If you want to help the germination along you can soak your seeds in water. It is best to to this for about two hours before you intend to plant them. You can sow directly outdoors if you are planting when it is nice and warm (August-September).

If however, you are starting the seeds in the spring, it is best to start them indoors. Using peat pellets is easiest. Soak the peat pellets in water and once they have regained their full size, put 1-2 seeds per pellet. Then pop them on a warming mat to speed them on their way.

How to Plant Rhubarb

So now that you know you want to grow rhubarb, let’s take a look at some the things that you need to do in order to get started.

1. Pick a sunny spot that has both fertile and well-drained soil.
2. Make sure to get rid of any weeds.
3. Dig through the soil and remove any stones and add as much organic matter as possible (this is where your homemade compost comes in really handy).
4. Dig large holes, spaced about 4 feet apart and add in some compost, rotted manure, or anything high in organic matter in the soil.
5. Plant the roots 1 to 2 inches below the surface of the soil. You want to make sure that the top of the plant is at, or just below the soil surface.

Where does rhubarb grow best?

While it is known as the plant you can’t kill, it does have its own form of kryptonite. And for rhubarb that is Zone 9 or higher. This plant needs to experience cold weather before it will begin growing in the spring. It does best when the winter temperature falls below 4ºC (40ºF) and summer temperatures stay below 24ºC (75ºF)

Rhubarb likes to grow in full sun, but given that it is so hardy it can grow in shade or partial shade. You just won’t have the best possible crop. Soil type is very important when growing rhubarb. It tends to prefer a moderately acidic soil and best crops are achieved when the pH is between 6.0 to 6.8. If you are not sure of your soil pH you can get a kit to test it out. It does not like clay soil and really requires a lot of organic matter such as compost and manure as it is a heavy feeder.

Can you grow rhubarb in containers?

Just because you can do something, doesn’t mean you should. The same can be said for growing rhubarb in containers. While it is possible, it’s not the best option. Rhubarb plants have really big root systems which means they need a lot of space to grow. This is hard to achieve in a container. That said if you have some really big containers that are able to hold at least 40 litres of compost you should be ok. But those are some seriously large containers and you would be better off just putting them in the ground. Just remember if you do decide to grow them in containers the medium you surround them with becomes that much more important. So you can’t just throw in soil and hope for the best. You have to load those puppies up with a sh*t ton on compost/manure.

How to care for rhubarb

Spring

Keep an eye out for any seed stalks or rhubarb flowers and remove them as soon as they appear. Its no cause for concern but you want to make sure that the plants don’t bolt and that they direct their energy into growing tasty stems. Mulch generously with a heavy layer of straw and cow manure to provide nutrients for the plant. This also helps to retain moisture and discourage the growth of any pesky weeds.

Summer

While we don’t want rhubarb getting soggy we also don’t want it to dry out. So during the summer months keep an eye on your rhubarb plants and water them during dry periods. If you are growing your rhubarb in containers, you will need to water a lot more. You need to make sure to keep the compost moist.

Fall

This is the time when the leaves die back naturally. All you have to do is cut back the old rhubarb stalks and the buds exposed. Time for a manure/compost top up around the crown of the plant. This will help to keep moisture in the soil and block weeds from growing. As an added bonus it will provide nutrients for the plants in the following growing season. But PLEASE make sure you do not cover the crown as this could lead to the dreaded crown rot.

Winter

Every 4-6 years you should divide the rhubarb crowns in order to keep them strong and productive. These can then be replanting separately or given to friends. Because sharing is caring. More on splitting rhubarb below.

Do I really need to split my rhubarb?

If you want to ensure that your rhubarb plants remain healthy then yes you should. It is important to split rhubarb root every 4-6 years. Make sure that you do this in the fall/winter when the plant has entered into a dormant state.

You can safely split each plant into three or four separate crowns with a shovel. It is important to ensure that each resulting crown has an ‘eye’. This is pretty much a large bud that will grow into next year’s shoots. 

Once you have split the roots you should dig holes slightly bigger than the new plant and put the crown in the hole. Make sure that the roots are facing down. It is also important to ensure that the top of the crown is about 2.5cm (1″) below the surface of the soil.

What is “forcing” rhubarb?

Forcing rhubarb is a pretty simple process. It’s goal is to provides an earlier harvest of stems that are sweeter and don’t require peeling. All you have to do is cover the plant so that it doesn’t not have access to light. If you are planning on doing this you should make sure to cover the plant as soon as you see signs of growth. The lack of light and the extra heat that the pot provides causes the rhubarb to ripen very quickly. Using this method it should be ready to eat within just 4 weeks.

As long as there is no light getting to the plant you can use pretty much any pot to force rhubarb. Thought there are special rhubarb forcing pots that you can buy as well, if you are so inclined.

What problems can rhubarb have?

Tom, my brother-in-law, was telling me a story once, about how his dad was trying to get rid of their rhubarb. He ran over it many times with the lawn mower and it still came back. He also shoved one down a rabbit hole and the plant is still there. So this is definitely a hardy plant, that said there are still some issues that can befall it. Let’s take a look at a few of them.

Crown Rot

Crown rot is the main issue you may encounter with your rhubarb. It is caused by a fungal infestation of that occurs at the base of the stalks. It causes the leaves to wilt and the crowns turn brown and soften. The main culprit of this is keeping the soil around your rhubarb too wet, making this a preventable catastrophe.  As this is a fungal issue it is important to immediately dig and destroy up any plants suffering from rot. To avoid crown rot, make sure rhubarb is planted in fertile, well-drained, weed-free soil. This is important as the fungus that causes it thrives in wet conditions. Also weeds can cover the crowns and increase the likelihood of this disease developing. So no weeds and no soggy soil, ok?

Red Leaf

There are two types of red leaf. One where the whole leaf starts turning red and another where red spots start appearing on the leaves. One is caused be a bacteria and the other by fungi. So let’s take a quick look at both and what can be done if the plague befalls your precious rhubarb.

If the entire leaves are turning red, then you have a case of Erwinia rhapontici bacteria. After the leaves start to turn red you will notice that the crown as well as the roots will start to rot. Sadly there is no cure for this and you will have to remove and destroy the plant (DO NOT PUT IN YOUR COMPOST). It is also important that you do not plant more rhubarb in the same spot.

If you just see nasty little red spots appearing on your lovely rhubarb leaves, then you have had exposure to one of two fungi (ewww), either Ascochyta or Ramularia. Unfortunately, the story with this type of red leaf is no better than the first. The plant must also be destroyed and no more rhubarb in the same location. Aphids are known to spread this type of fungus so attracting helpful ladybugs to the garden can help to prevent its spread.

Slugs and snails

These garden pests LOVE rhubarb leaves (go figure), they tend to attack the fresh new leaves that are close to the ground. There is no need to freak out, most rhubarb plants can handle some leaf damage from these little guys. You can always dig a hole, pop in a plastic container, making sure that the top of the container is level with the soil. Then fill it with beer and voila, you have a slug trap. Another option is to put crumbled up eggshells around the plants.

How to harvest rhubarb

So you have grown some amazing rhubarb, avoided any pests or plagues and now it is time to reap the benefits of your work. Harvesting rhubarb is quite easy but there are a few things to keep in mind.

• As previously mentioned (a few times) do NOT harvest any stalks in the first year, so that your plants can become established.
• The best time to harvest is in the spring and fall, while it is possible to harvest during the summer it can stress the plant.
• Wait until your plant has at least 10 stalks and then you can harvest 3-4 at a time. Make sure to choose stalks that are 12-18 inches long whose leaves have fully opened.
• If you notice that the stalks are becoming thin and spindly then stop harvesting. This means that the plant’s food reserves are low.
• To harvest a stalk, just grab the base and pull it away from the plant with a gentle twisting motion. If this doesn’t work, you can cut the stalk at the base.
• Put the leaves in the composter, like now, you don’t want them sitting around.

Can you freeze rhubarb?

Yes you can, and you should! In order for rhubarb to build up energy reserves it needs to grow in the next season, it is very important that you stop harvesting by the end of July. So make sure to harvest any rhubarb before then. BUT make sure to leave at least two stalks per plant!

So assuming you have more rhubarb than you need after the final July harvest then best solution is to freeze it! Luckily, rhubarb freezes really well so why wouldn’t you take advantage of this? Give it a quick rinse and dry it off. Lay out some parchment paper on a cookie sheet. Chop up the rhubarb into 1″ pieces and put them on the parchment paper. Pop the cookie sheet in the freezer until it is frozen. Once it is frozen and if you are lucky enough to have a vacuum sealer (I am obsessed with mine and use it for everything) then that would be your best bet. If not, then grab a freezer bag and pop it all in until you are ready to use it.

The Hubby loves my rhubarb and strawberry jam. I’m also curious to make a rhubarb ginger jam as well as a rhubarb crumble…but those are recipes for another day.

What is your favourite thing to make with rhubarb?

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