Search
  • email10815

GROW GUIDE - POTATOES

Potatoes are one of the staple plants of a spring garden, and there are many reasons to grow your own rather than supermarket stock. This year we will have 32 varieties in stock, far more than the two or three you can find at a supermarket!



Different types of Potato

Potatoes can be broken down into three growth types and two-three texture types, the growth types determine how quickly the plant grows and when potatoes should be harvested whilst the texture types help tell what the potato can be used for.

First Early potatoes are harvested early and are often used for boiled or salad potatoes, they are avoidant of blight as they are often harvested before it has made an appreciable appearance. They have an average time of harvest of 10 weeks although some may be left later to mature slightly giving them a stronger taste and sometimes shifting them more towards the floury scale. They are often smaller plants than other potatoes and can be planted closer together. Plant these potatoes in March

Second Early potatoes are planted at the same time as first early, in March but they mature for longer at about 13 weeks. They are often heavier croppers than First Earlies but not as heavy as main crops. These lean more towards the floury side of the scale and are often mid-range, although as always there are exceptions to the rule.

Main Crop potatoes are much more productive than the earlies however they also have a natural susceptibility to blight so should be looked after. These often are the most flavoursome potatoes with larger floury tubers that are ideal for baking. They can take up to 15 weeks to be ready for harvest. They ideally are planted in late March / April.

2nd Main Crop potatoes do exist, these are often planted late April and can take up to 20 weeks to mature however they are very prone to blighting and therefore are not often grown in this country. These often have very large tubers which are packed with flavour. Unfortunately as potatoes are not suited to grow in greenhouses (the warmth inhibits tuber growth) they can be very problematic in blight prone areas.

The texture of a potato is the most important thing to consider when cooking potatoes, If they are floury then they can be prone to breaking up when boiled (as they absorb water with ease) whilst if they are overly waxy they may be able to be boiled for hours on a low heat but they make poor roasts. The middle of this scale is called firm, where the potato has enough dry matter to make a good roast but dose not break up readily when boiled, making it a good general purpose workhorse.

Floury potatoes have a high dry matter content meaning they produce fantastic light roast, baked and mashed potatoes. This is both a benefit and a problem as the floury starch absorbs butter and milk with great aptitude however they also have a tendency to collapse when boiled as they absorb too much moisture.

Firm potatoes are a midway point between the waxy and floury potatoes, they are usefully for many purposes, as they provide more taste and a better texture as roasts than waxy but are more likely to withstand boiling than floury. They are ideal for chips and wedges.

Waxy potatoes tend to be early as they have not fully developed the starchiness of main crop potatoes however there are exceptions. A waxy potato often has a thin slightly translucent skin which is easy to rub off. These are ideal for boiling as either new potatoes or as salad potatoes. Some varieties can be boiled for hours, making them ideal for restaurants where there can be long waits between meals.


How to Propogate

Potatoes are normally grown from seed potatoes from elevated North Scotland (as the main vector for diseases is the aphid which is entirely unsuited to the climate) However it is possible to use saved potatoes for planting and it is even possible to take stem cuttings from any misplaced potatoes from last year (as long as their still in good condition). To do this the potato must have started sprouting and often the tuber has started to whither. At this point then take the stems off the plant with a sharp knife (weak stems could do with a small chunk of potato as this is after all a food store) and are planted, stem point down into damp compost kept inside a house (ideally multipurpose as it is lighter and easier for new roots to develop in).

It is important to keep the soil lightly moist however never wet, the potatoes should quickly root within a few days if kept in a warm location. These potatoes can be planted out along with your early potatoes and will mature quickly, having had a head start therefore providing a tasty precursor to your later cropping.


How to Grow

Potatoes are among the easiest plants to grow, part of the reason they are so wide spread and popular among armature growers. There are several methods of how to grow them, however relevant to all of them are a few basics:

First and most importantly- Never use contaminated potatoes or potatoes thought to have been infected with disease, especially blight. Secondly, potatoes grown in the light produce green skin which is poisonous (not deadly just unpleasant) Thirdly, potatoes grown in overly warm conditions stop producing tubers, therefore potatoes grown in pots produce lower yields Finally, potatoes should in most circumstances be 'earthed up' therefore promoting more growth and reducing the chance of green potatoes

Potatoes are one of the few vegetables that prefer a loose soil to a heavy and having an acidic soil is not only their preferred environment (5-5.5 pH) it also reduces greatly the likelihood of powdery scab. It is worth, especially if planting in soil to plant potatoes with a thick mulch of grass clippings as these will acidify and lighten the soil whilst providing a good dose of nitrogen as they break down. With potatoes avoid over-watering until tubers start to form as this will promote a lot of foliage growth at the expense of the tubers. After they have started to form however. water as much as you want.


Chitting

Chitting is the act of causing the potato to sprout before being planted in the soil, this effectively gives the potato a head start as it is already active when planted. The normal method is to place a potato in an egg container and keep it in a warm, light position, in addition this can turn the skin of the potato green as it produces unpalatable toxins which stop animals attempting to dig and eat it. This method is best used with earlies but can also be useful with main-crop potatoes.

It is also possible to divide potatoes if they are large enough. By cutting a potato, as long as it has at least one active eye you can replicate it as a vegetative clone. It is however best if the section is bigger than a golf ball or ping-pong ball and to ensure it produces a strong plant, 2-3 eyes should be active or sprouting. When the potato is split then it is best not to plant it immediately as if left to dry it will seal itself and therefore it is more resistant to infections attempting to attack the wound. Do not worry if it appears to go black or shrivel slightly that's normal!


Traditional Method

The 'Traditional Method' is still the most practised today as it is well proven and provides greater yields with less care than either the pot or no dig method. This method focuses around the initial planting and a constant earthing up (either with soil or mulch) to effectively extend the tuber producing underground stem of the potato and to minimise green skins.

You can plant the potatoes in raised beds (high yield), trenches (ideally mulched with grass cuttings), raised mounds (ideal in clay gardens or to reduce work) or raised rows (Ideal for allotments). after they have been planted, in whatever form they should be covered over with ~10cm of soil. The traditional way to do this has been to simply rake soil from the surrounding area, thus providing drainage and smothering weeds however in heavy soils then a light compost may be better. This should be done regularly as soon as the potato tip appears. After 4-5 earthlings then allow the potato to grow, keeping it watered as tubers start to grow. With potato mounds, it is possible if they are large enough to check and harvest some of the more mature potatoes without destroying the plant.