Gadenin日本語Get the appThe seed is a raw kernel, and it is fragile
A peanut seed is the kernel itself, shelled from the pod. It has no hard protective coat like a bean; the skin around it is a thin papery membrane, and the two halves of the kernel are joined only at the small embryo at one end. If that skin is rubbed off, or if the halves separate while you are shelling, the seed will not grow. Handle the kernels the way you would handle eggs and shell them the same day you sow, or at most the day before.
Buy or save seed still in the shell and leave it in the shell until sowing day. Kernels stored loose lose viability fast, dry out unevenly and pick up mold. Do not use roasted or salted nuts from a food shop under any circumstances, and do not use blanched kernels, which have had the skin removed. Raw in-shell seed, kept cool and dry, germinates at close to ninety percent; loose supermarket kernels typically manage nothing at all.
- Shell by hand on sowing day Crack the pod at the waist and lift the kernels out whole. Do not press them out with a thumb against the shell, which splits the halves apart.
- Keep the skin on The reddish or pink papery skin protects the kernel from soil fungi. A kernel that has shed its skin is worth discarding; it usually rots before it sprouts.
- Sort out the small and shriveled Sow only plump, full-sized kernels. Small or wrinkled ones produce weak plants that flower late and never fill their pods before frost.
- Do not soak overnight A long soak splits the halves and drowns the embryo. If your soil is very dry, water the row the day before instead and sow into moist ground.
Wait for the soil, not the calendar
Peanut is a warm-season crop from the subtropics and it does nothing useful in cold ground. Below 60F (15C) the kernel sits and rots rather than sprouting. Sow when all danger of frost has passed and the soil at four inches (10 cm) deep has held above 65F (18C) for a week, which in most temperate gardens is two to three weeks after the last frost. At that temperature seedlings break the surface in seven to twelve days; at the borderline they can take three weeks and lose half the stand to rot.
Count your season before you sow. From sowing to a mature crop is 120 to 150 frost-free days depending on the type you are growing, and the pods keep filling right up until the plant is lifted. If your frost-free window is shorter than about 120 days, start the seed indoors in deep pots three weeks before your outdoor sowing date and set the plants out with the root ball intact, or grow under black plastic to gain warmth at both ends.
| Soil at 4 in (10 cm) | Days to emergence | Verdict |
|---|---|---|
| Below 60F (15C) | Usually none | Too cold. Seed rots in the row |
| 60 to 65F (15 to 18C) | 14 to 21 days | Marginal. Expect gaps in the row |
| 65 to 70F (18 to 21C) | 8 to 12 days | The reliable window for open ground |
| Above 70F (21C) | 5 to 8 days | Fast and even, if moisture is steady |
Depth, spacing and the ground it goes into
Sow the kernels an inch and a half to two inches (4 to 5 cm) deep, pointed end down or laid flat, in ground that has been forked loose to a full spade depth. Space them six to eight inches (15 to 20 cm) apart in rows two to two and a half feet (60 to 75 cm) apart. That spacing looks generous when the seedlings are small and is exactly right by midsummer, because the plant spreads sideways and every inch of ground it covers is ground where it will later try to set pods.
The soil matters more here than for almost any other vegetable. Peanut is one of the few crops where the fruit forms underground after the flower has already opened above ground, so the surface soil has to stay soft enough for a thin stalk to push into it. Loose sandy or sandy loam ground is ideal. On heavy soil, dig in coarse sand and finished leaf mold over the whole bed rather than just in the planting hole, and raise the row into a low ridge so it drains and warms.
Do not lime the bed at sowing unless a test shows the pH below 5.8. Peanut wants a pH of about 5.8 to 6.5, and over-liming at sowing locks up the manganese and boron the plant needs later.
Nitrogen, inoculant and the first fortnight
Peanut is a legume and fixes its own nitrogen once the right soil bacteria colonise its roots. If peanuts have never grown in your garden, treat the seed with a peanut-specific rhizobium inoculant on sowing day; the powder for peas and beans is a different strain and does nothing. Where no inoculant is available, work a couple of inches of finished compost through the bed and accept that the first year will be slightly less vigorous than the second.
Do not add a nitrogen fertilizer. A well-nodulated peanut given extra nitrogen builds a huge leafy bush, flowers late and sets pods poorly, exactly as it does when planted in over-rich ground. What it does want at sowing is potassium and, from flowering onwards, calcium. Keep the row weed-free and evenly moist through the first fortnight; once the first true leaves are up the plant is tough and needs very little attention until it starts to flower.
- Water the row, not the whole bed Keep the top two inches of the sown row moist until emergence. Watering the bed generally encourages weeds you will have to pull later, when pulling is risky.
- Thin only to remove doubles Peanuts resent root disturbance. If two seedlings come up together, cut one off at ground level with scissors rather than pulling it out.
- Log the sowing date and the row position Write down the date, the soil temperature you sowed at, and where in the bed each row sits. Peanuts should not follow themselves, and next year you will not remember.