Gadenin日本語Get the appDepth of pot matters more than width
A tulip needs six to eight inches (15 to 20 cm) of compost above the bulb, and a couple of inches below it for roots, so the pot needs to be at least ten inches (25 cm) deep. Wide shallow bowls are the standard reason potted tulips come up short and flop; there is simply nothing anchoring the stem.
Width sets how many bulbs you can fit, and in pots you can plant far closer than in the ground. Bulbs an inch (2 to 3 cm) apart, almost but not quite touching, give the dense column of flowers that makes a potted display work. In open ground that spacing invites rot, but a free-draining pot dries fast enough to get away with it.
Use a gritty, free-draining mix: a soil-based compost with around a third by volume of coarse grit or perlite. Peat-based all-purpose potting mix on its own holds too much water through winter. Make sure the drainage holes are clear and stand the pot on feet so water leaves freely; a pot standing in a saucer of winter rain will rot everything in it.
Layering bulbs to stretch the display
Because a deep pot has room for more than one level, you can plant bulbs in two or three layers, deepest first. The shoots from the lower layer simply find their way around the bulbs above them. Done with types that flower at different times, one pot can carry six weeks of flowering instead of two.
Put the largest and latest bulbs at the bottom, cover with a few inches of compost, set the next layer between the positions of the ones below, cover again, and finish with the smallest and earliest bulbs near the top. Water once when the pot is finished and then leave it.
Do not layer bulbs directly on top of each other. Offset each layer so that every shoot has a clear route upwards, and keep the top of the highest bulb at least four inches (10 cm) below the compost surface.
| Layer | Depth below surface | What goes there |
|---|---|---|
| Bottom | 8 to 10 inches (20 to 25 cm) | Largest bulbs, latest to flower |
| Middle | 6 inches (15 cm) | Mid-season tulips, offset from the layer below |
| Top | 4 inches (10 cm) | Earliest and smallest bulbs |
| Surface | At the compost surface | Optional grit mulch to shed rain and deter squirrels |
Getting pots through winter
Compost in a pot freezes far harder and faster than garden soil, because cold reaches it from every side. In a cold winter, group pots together against a sheltered wall, or sink them into a spare bed or a heap of bark so the roots are insulated. Terracotta that stays saturated and then freezes will often crack.
The bulbs themselves are hardy and want the cold; it is repeated freeze-thaw cycles and waterlogging that do the damage. An unheated garage, a cold frame or a shed works well in severe climates, provided the pots go outside again once the worst has passed and get the light they need as shoots appear.
Keep pots barely damp through winter, checking every two or three weeks. A pot under the eaves gets no rain at all and can dry out completely, which stalls rooting. A pot in the open through a wet winter may need tipping or moving under cover. Neither extreme is what you want.
- Plant in the same cold window as the ground Wait until the weather has genuinely cooled, in mid to late autumn, before filling pots. Warm compost has the same tulip fire problem as warm soil, and pots warm up faster in sun than open ground does.
- Water once, thoroughly, then stop One good soak after planting settles the compost and starts the roots. After that only enough to stop the pot going bone dry, until shoots appear in late winter.
- Cover the surface against squirrels A layer of coarse grit, or a square of wire mesh cut to fit inside the rim, keeps rodents from digging. Pots are far more attractive to squirrels than beds because the compost is soft.
- Bring them forward when shoots appear Move pots to their display position once shoots are a couple of inches (5 cm) high. Until then they are better off in the coldest spot you have.
Pots dry out fast once growth is in full swing in spring. From the point where buds show color, check every second day and water at the compost surface rather than over the leaves.
After flowering: what to do with the pot
Potted tulips rarely repeat well. The compost has limited nutrition, the pot stays cool and often damp through summer, and the bulbs split rather than rebuild. The honest approach is to treat them as a single-season display, compost the spent bulbs and start with new ones each autumn.
If you want to try keeping them, move the pot somewhere sunny and out of the way as soon as flowering ends, deadhead, feed once with a high-potassium liquid feed, and let the foliage die back naturally without watering. When the leaves are gone, tip the pot out, sort the bulbs by size, discard anything smaller than about an inch (3 cm) across and store the rest dry.
Do not simply leave the pot standing where it is over summer and hope. A pot of old compost that gets watered along with everything else on the patio is the most reliable way to rot the bulbs entirely.
Keep a note of the pot size, how many bulbs went in and how many layers you used. Container displays are easy to repeat exactly once you know the numbers, and easy to get wrong from memory.