When to Plant Potatoes: The Complete Guide to a Rich Harvest

Many keen gardeners spend March and April checking the weather app: the bags of seed potatoes are ready, the neighbour has “already planted theirs ages ago”, yet doubt remains. Looking closely at the soil, weather and planting stock will determine whether you end up with only a few meagre tubers or a well-stocked cellar.

The right time to plant potatoes: soil matters more than the date

Dates printed on seed packets or given in gardening guides are only broad indicators. Experienced growers use a different measure: soil temperature. Potatoes will only make vigorous growth when the ground is sufficiently warm and dry.

“A soil temperature of around 7 to 10 degrees at a depth of ten centimetres is ideal – only then should the tubers go into the ground.”

For a precise reading, buy a soil thermometer from a garden centre. They are inexpensive and can prevent considerable disappointment. Once it consistently reads above 10 degrees, planting can begin. In many areas, the suitable period broadly falls as follows:

• Mild regions, coastal sites and the Upper Rhine: usually from late March
• Central Germany and many urban areas: often from mid-April
• Cooler locations and upland areas: more commonly from early to mid-May

If you do not have a thermometer, use a straightforward test: sit directly on the bare soil for a few minutes. If your bottom feels cold straight away, it is still too chilly for potatoes. If you can sit comfortably, the time to start is close.

Later is better than too early: protection from cold pays off

Many gardeners make the same mistake: eager to get started, they put tubers into icy clods of earth. The result is that they sit for weeks in cold, wet ground, sprout reluctantly and are prone to rotting. Waiting a little longer generally produces far better results.

“It is better to wait a week than plant into frozen ground – potatoes reward patience with stronger plants and larger tubers.”

Those living in cool areas, or hoping for a particularly early crop, can give the soil a helping hand. Black mulch film or black plastic warms the ground by two to three degrees, often allowing planting one to two weeks sooner. Crucially, lay the film over the prepared bed several days before planting so the layers below have time to warm properly.

Potato soil requirements: loose, humus-rich and free-draining

Potatoes form their tubers underground. The looser and more open the soil, the more easily roots can develop and the more evenly the tubers will grow. A quick hand test reveals the condition of the ground: if you can squeeze a handful of soil into a sticky, hard ball, it is too heavy and clay-rich.

Garden professionals recommend the following for productive potato beds:

• Spread three to four centimetres of mature compost over the area in autumn.
• Work in some sand where soil is very heavy to improve its texture.
• Loosen the bed deeply and break up any large clumps.
• Leave at least four years before growing potatoes in the same place again.

This crop break substantially lowers the risk of diseases such as potato blight and nematodes. If your garden is small, use large containers or potato-growing bags instead, which also gives the beds a rest.

The right tubers: why certified seed potatoes beat supermarket potatoes

Cheap eating potatoes from the supermarket often end up in the bed as an emergency option. Specialists advise against this. Many of these tubers have been treated with sprout inhibitors, may carry diseases and frequently give unexpectedly poor yields.

“Certified seed potatoes have been checked for health – they establish more strongly, sprout more evenly and crop more reliably.”

Certified seed potatoes also make planning easier: around 1.5 kilograms of planting stock will produce roughly 10 to 20 kilograms of potatoes, depending on the variety and care provided. If you want an earlier harvest, give the plants a head start by chitting them, which starts their shoots before they are planted out.

Chitting: a four to six-week head start

To chit seed potatoes, place them in shallow trays or empty egg boxes four to six weeks before the intended planting date. Position the tubers close together without stacking them. A bright, cool place at around ten to fifteen degrees is suitable, such as a north-facing window or a light hallway.

• Arrange the tubers with most of their “eyes” facing upwards.
• Choose somewhere bright but away from full sun.
• Do not use a jet of water or a spray bottle – the potatoes should remain dry.
• Wait until the shoots are around one to two centimetres long.

Chitted potatoes get growing immediately once planted and provide the first fresh tubers several weeks ahead of unchitted stock.

Planting day: spacing, depth and sunshine step by step

On planting day itself, the soil should be lightly moist rather than soaking wet. Ideally, choose a position in full sun where the bed can dry rapidly after rain. Waterlogging in spring is harmful to the tubers.

1. Make furrows: Use a hoe or spade to create trenches ten to fifteen centimetres deep.
2. Keep the correct spacing: Leave around 30 to 35 centimetres between tubers within each row, and roughly 60 to 70 centimetres between rows.
3. Place them correctly: Set chitted potatoes in the furrow with their shoots pointing upwards.
4. Earth up lightly: Cover the furrows with loose soil without snapping the shoots.

The same basic method works in large containers or potato-growing bags: add a layer of loose soil at the bottom, lay in the potatoes, then cover them with more soil. As the plants grow, gradually top up with soil or loose growing medium.

Earthing up: the secret to more tubers

Once young plants reach around twenty centimetres tall, it is time for a key task: earthing up. Draw soil from between the rows towards the plants to create small ridges that partly cover their stems.

“Earthed-up potatoes stay in the dark, grow more securely and often produce more and larger tubers.”

Earthing up for a second time after a few weeks intensifies this benefit. It also smothers many weeds and shields developing tubers from sunlight. Potatoes that turn green at the surface produce toxins and should not be eaten.

Regional differences: why planting cannot always begin in March

What you see in your own garden matters far more than comparing your progress with friends in other parts of the country. While potato beds may already be turning green in mild wine-growing areas during March, snow can still lie at the edge of woodland in the Alpine foothills.

For greater certainty, observe your surroundings carefully over one or two years: when do forsythias flower, when do fruit trees come into leaf, and when do nights stop being regularly frosty? These natural signs often correspond remarkably well with the period in which potatoes reliably begin growing.

Practical extra tips for a generous potato harvest

Alongside planting time and soil preparation, variety choice and ongoing care have a major effect. Early potatoes provide tender, thin-skinned tubers for the barbecue as early as June or July. Later varieties are better suited to storage and can supply the household throughout winter.

Variety	Maturity group	Typical use
Annabelle	early	Salads, baked potatoes
Siegfried	mid-early	Mashed potato, purée
Bintje	late	Chips, storing potatoes

Low-growing vegetables such as spinach or radishes can be planted between the rows. They make use of the space while potato plants are still small and will usually be harvested before the foliage casts heavier shade. This gives a substantially higher yield from a limited area.

Why crop rotation and cleanliness keep diseases at bay

Potatoes belong to the nightshade family, along with tomatoes and peppers. Growing these crops in the same place year after year practically invites disease organisms in. Follow these clear rules instead:

• Wait at least four years before planting potatoes in the same bed again.
• Do not plant tomatoes or peppers immediately after potatoes in the same spot.
• Do not compost diseased foliage; dispose of it with household waste instead.

This keeps soil healthy over the long term, so plants have fewer problems with fungal disease or pests.

Additional advice: watering, mulch and smaller risks

Potatoes need consistent moisture but cannot tolerate permanently wet conditions. Prolonged dry spells while tubers are forming lead to smaller crops and can sometimes cause potatoes to split. A light organic mulch of grass clippings or chopped straw retains moisture in the soil more effectively and reduces the need for watering.

Take particular care when growing in bags or containers: the growing medium dries out more quickly, while heavy containers can also become waterlogged. Water must always be able to drain away freely from the bottom.

The final stage is particularly satisfying: carefully dig out the first new potatoes by hand or with a small hand fork a short distance from the plant, without lifting the whole plant. The remaining tubers can then stay in the ground and continue growing. By choosing the right planting time and following these few rules, you can fill storage boxes in the cellar without stress by late summer.