Hey you all!
For like literally the first time this year it has been the ideal moment to plant my potatoes. It was (a) dry outside, (b) not freezing and (c) I was off work. So, out to the garden!
Potatoes are in my experience one of the easiest vegetables to grow. The downside however is that potatoes require a relatively large piece of land and they take a lot of nutrient out of the ground, resulting in soil in desperate need of fertilizer. Nonetheless, young homegrown potatoes have a softer taste that store bought ones which makes it worth while. Plus, harvesting potatoes with your children is lots of fun! Have them looking through the turned-up soil searching for them all. My eldest loves this! We always end up missing a few which I discover at the end of the season when I fertilize the soil or in the next season when I suddenly have a potato growing between other vegetables.
So, how do you go about growing potatoes?
Step 1 – Ordering tubers
It is important to order potatoes early because they need time to sprout. I order my potatoes such that I have them no later than mid February and I always order two kinds, one for an early and one for a late harvest. I receive them at the same time, even though they do not go into the ground at the same time. This is not a problem as the late harvest potatoes simply sprout a bit longer.
I order my potatoes, as all my other seeds, from Zaadhandel van der Wal. They have many varieties to choose from and deliver fast to addresses in The Netherlands. You can best order the smallest package that is offered by your supplier. The reason is that there are always more potatoes in a package than you actually need and most often there are also more potatoes in the package than the estimate given by the supplier.
Step 2 – Sprouting potatoes
It is not compulsory to sprout potatoes, but it does give them a head start. Sprouting is particularly important for early harvest potatoes and requires at least three weeks. I always receive all my potatoes at the same time, meaning that my late harvest potatoes sprout a bit longer before going into the ground.
Sprouting happens when you leave the potatoes in a light, cool place where temperatures remain well above freezing. Ideally, the temperature should be around 12oC (54oF). I usually keep my potatoes in the scullery, or if it’s warm enough, in the garden shed. Take the potatoes out of their package and place them such that the side with the most eyes is facing upward (this is the side containing small dots). I place my tubers in old egg cartons. The holes in the cartons are perfect to keep the tubers right side up and helps to prevent damaging the sprouts when moving the tubers.
After at least three weeks there should be green sprouts on the potatoes. These sprouts are a few centimeters (approximately half to one inch) long and can contain a few small leaves. If the sprouts are long and white the tubers were kept in an environment which was too dark. Long, white sprouts are weak and break easily.
Step 3 – Planting the tubers
Planting your sprouted tubers is the next step. Early potatoes can be planted from half March, if the ground is no longer frozen. Late harvest potatoes can be planted from end of April until beginning of May, although I have planted late harvest potatoes at the end of March in a warm year. Late harvest potatoes are slow growers, so the few extra weeks gained by planing them early makes little difference at the end of the day.
I dig trenches 20cm deep, 50cm apart. I plant the tubers 15cm deep in the middle of the trench, and approximately 15cm between potatoes in a trench.
When planing your tubers make sure not to break the sprouts as you will loose the head start the sprouts gave you. However, if you have short sprouts, the change of this happening is small. It can take anything from one to three weeks, depending on the weather, for the first leaves to appear. Make sure to give your tubers and young potato plants enough water to make sure they grow well.
Step 4 – Earth-up
Earthing up is the process where earth/soil is heaped over the plants to ensure that the newly developing potatoes remain underground. When potatoes are not covered properly they turn green and are no longer edible.
When the plants are 20cm in height it’s a good time to earth up for the first time. I earth up by closing the trench I planted the potatoes in. Inevitably you will cover a part of the leaves of the potato plants when earthing up your potatoes, but this is not a problem. Just make sure that there is still enough of the plant visible so that it can continue growing.
When the trenches are closed completely, I use the soil between the trenches to cover the potatoes. In my experience you need to earth up two or three times in a season.
Step 5 – Preventing and treating diseases and bugs
Potato disease, or Phytophthora, is one of the most serious diseases that can hit your potatoes. Except using poison there is not much you can do to prevent it. Hence you have to make a choice, either go completely biological and hope for the best or take chemical measures to prevent your potatoes from getting ill. You can only take preventative measures, once the disease has struck there is nothing you can do.
In 2010 I had Phytophthora in my late harvest potatoes and lost the entire harvest as I caught it too late. You can recognize the disease from the brown spots that form on the leaves and after some time the plant dies and the potatoes rot away. The moment the leaves show the first symptoms you can best harvest all your potatoes, even if they are not fully grown yet. By doing this you can save about 80% of your potatoes. You will have to check your harvest every week for rotting potatoes and remove them to keep the rest from rotting away. This way you will have at least a partial harvest.
I once had rough patches on my potatoes. I have no idea what this is in English, in Dutch we call it ‘schurft’. These are rough spots on the potato, and although it doesn’t look very nice, you can still use and eat them. It is caused by too little moisture during the growth period of the potato.You can prevent this by watering your potatoes, especially during warm dry spells. Like I said, don’t worry about this.
When it comes to bugs the potato is again a sensitive plant. When the weather is warm, typically above 20oC (68oF) you can expect the Colorado Potato Beetle to make his appearance. It is actually a really beautiful beetle, but it can reek havoc on your plants. Make sure to catch and kill them all! If you don’t remove them, their orange eggs hatch and the larvae eat your potato plants to the ground. The larvae look a bit like lady bugs, but much less nice in nature. In warmer weather you will have to check your plants daily. Also check underneath the leaves for those telltale orange eggs! When you find eggs or larvae make sure to kill them and DON’T just through them in the bin alive. I usually pore boiling water over them.
Step 6 – Harvesting
Cut off the leaves of the late harvest
Approximately two weeks before harvesting your late potatoes, cut off the leaves of the plants. This will make the potato’s skin tougher.
Harvesting potatoes is one of the most fun things to do with my kids, mine just love to help. It takes about 90 days from planting to harvesting and often, but not always, the potatoes are flowering when they are ready for harvesting. To harvest your potatoes, simply put your gardening fork in the ground at a reasonable distance from the stem of the plant and bring the soil up. Work from the outside in and try not to hit any potatoes in the process. The potatoes should be visible and now it is a free for all! It’s a good idea to let the potatoes dry an hour or two in the sun to let the skin harden.
It is impossible to prevent not damaging any potatoes during the harvest. Keep the damaged ones to the side and eat them first. Early potatoes you can harvest as needed, late potatoes you can best harvest all in one go.
Step 7 – Storage
Store your potatoes in a cool, dry and dark place so that they don’t start sprouting. Inevitably, at a certain point they will start sprouting anyway. If you want to prevent this you can treat your potatoes with an anti-sprouting powder. BUT DO TAKE NOTE: do not put potato peels from potatoes that have been treated with anti-sprouting power on your compost heap as this will kill all the useful bacteria and bugs in your compost heap!