Gadenin日本語Get the appDo not miss the planting window
The window is short: the soil still has to be warm enough for roots to move, but hard frost must not have arrived. Reckon on about three weeks for roots to take hold, and judge whether you still have that many days of workable soil.
Plant a month late and the ground freezes before the roots are down, frost heave pushes the plants out, and most of them die. If you are forced to plant late, mulch generously around the plants with husks or compost to slow the freezing.
| Type | Planting | Spacing |
|---|---|---|
| Very early | Earliest in the window | 5 in (12 cm) |
| Early | Middle of the window | 5 to 6 in (12 to 15 cm) |
| Mid maincrop | Middle to late | 6 in (15 cm) |
| Late maincrop | Latest in the window | 6 in (15 cm) |
If the soil is sticky after rain on the day you planned to plant, wait a day. Planted into puddled soil the roots do not extend and establishment is visibly slower.
Prepare the bed first
Onions dislike acid soil and want a pH of about 6.0 to 6.5. Lime at least two weeks before planting and dig it in. Do not lime and fertilize on the same day, because nitrogen is lost. Leave a week between them.
- Lime two weeks ahead Where the soil is acid, apply lime and dig it in. On acid ground the roots do not spread and the bulbs never size up.
- Base fertilizer a week ahead Work in well-rotted compost and a balanced fertilizer across the bed. Keep this separate from the liming by a week.
- Make the bed high and wide Two to three feet wide and at least four inches (10 cm) high. Keeping the roots out of standing winter wet is the single highest priority with this crop.
- Lay mulch before planting If you use black plastic, lay it as soon as the bed is made so it settles. The spacing of the holes becomes your plant spacing, so a six inch grid is convenient.
Black plastic holds warmth in the soil and cuts both weeds and frost heave. It is the easiest way to reduce winter losses on an exposed plot.
How to plant
Planting depth is the one measurement worth getting right. An inch too deep buries the growing point, an inch too shallow and frost lifts the plant out over winter.
- Space five to six inches apart Six inches (15 cm) for large bulbs, five inches (12 cm) if you would rather have more, smaller ones. Any closer and the plants compete as they bulb, and every bulb comes small.
- Plant about an inch deep Deep enough to bury the white base with the point where the leaves divide sitting at the surface. Make a hole with a dibber, drop the plant in and firm soil around it.
- Do not plant deep Bury the point where the leaves divide and the growing point is underground: the bulb comes out flattened or growth simply stops. Too shallow and frost heave lifts it. That inch of difference is what matters.
- Firm and water Press the soil around the plant so the roots make contact, then water thoroughly. In most gardens that is the only watering the crop needs until spring.
Do not bend the roots to force them into the hole. Trimming long roots back to about an inch before planting gets new roots away faster.
Sorting bought plants
Bought onion plants come in bundles and the thickness varies a great deal. Undo the bundle first and sort into three grades by the thickness of the base. Plant the quarter inch ones as your main crop, the fat ones at the end of the row, and the thin ones closer together in a separate row.
| The plant | What it means | Plant it? |
|---|---|---|
| Base 1/4 in (5 to 7 mm) and firm | Right for the window | Main planting |
| Base over 1/3 in (8 mm) | Likely to bolt | At the end of the row, eat early |
| Only the leaf tips dry | Just dried out in the shop | Trim the leaves and plant |
| Base soft and brown | Diseased or rotting | Do not plant it |
If you cannot plant straight away, heel the bundle into soil in the shade and water it. Left in the bag for days they sweat and spoil.
Telling whether they have taken
For about ten days after planting the leaves lie flat and yellow. That is normal, not a failure. Two or three weeks in, a new leaf standing up from the center and a deeper green mean the plant has rooted. A gentle tug that meets resistance tells you the same thing.
If a month later the leaves are still flat and the plant pulls straight out, there are no roots. The cause is planting too deep, drying out, or damaged roots. If only a few are affected, sowing a leafy crop in the gap in spring wastes less than trying to replace them now.
| A month after planting | Likely cause | What to do |
|---|---|---|
| New leaf standing from the center | Rooted | Leave it to overwinter |
| Leaves flat and yellow | Roots have not moved yet | Firm around the base and add mulch |
| Pulls straight out | Planted deep or roots damaged | Replant shallower, or fill the gap |
Three things to do on planting day
Three jobs done the same day noticeably reduce winter losses. Each takes minutes, but they only work before the roots are down, so putting them off makes them pointless.
- A thin mulch Husks or straw around the plants even out the wetting and drying and reduce frost heave. Keep it thin, or the growing point ends up buried.
- Label the rows Push a label with the variety and the planting date in at the end of each row. Early and late varieties are two months apart at harvest and you cannot tell them apart by leaf in spring.
- Cut a drainage channel Run a shallow channel along the foot of the bed and out to somewhere the water can go. Standing water in winter is the single biggest cause of root rot and soil-borne disease.