How to force your own bulbs

Val Bourne / 28 November 2013

During early winter garden centres have tiny potfuls of bulbs that have been persuaded to flower precociously early by being exposed to gentle heat. These were planted in the autumn and kept cool for many weeks, before being brought into a warm glasshouse.



Most are miniature bulbs, always the earliest to flower, and these small pots can be planted up together in containers close to the house, or brought indoors.

Outdoor pots

One of the most useful ways to make use of these inexpensive potfuls is to plant up a container with leafy evergreen plants that might include Skimmia x confusa ‘Kew Green’, or Sarcococca confusa, or wintergreen ferns, or Christmas roses  - Helleborus niger

When potting them up together, insert an empty three-inch pot into the plants, to create a gap. This can be removed and replaced with a succession of flowering pots that can start with cyclamen, snowdrops and Narcissus ‘February Gold’, going on to wood anemones and scillas. 

When choosing cyclamen, opt for the hardy Cyclamen coum rather than the showier bedding varieties. The latter aren’t suitable for outdoor use, unless the position is very sheltered. These can be used in porches, or in cool rooms.

How to force your own bulbs

Forcing bulbs is very easy, but the technique is slightly different from planting outdoors. The bulbs are spaced closely together and their noses are exposed above the compost. Use round black plastic pots if possible: they are are warmer because black absorbs heat and the round shapes fit into cache pots.

Use John Innes no 1 and partly fill them up so that the bulbs rest on top. Then fill the pots up, leaving a half-inch gap at the top for watering. Do not firm the compost - keep it airy. Water them well and then place them in a cool shed in the dark. 

A sheet of plywood keeps out the light - being in a cool dark place prompts slow root growth. If they were placed indoors straight away they would be straggly instead. 

Larger bulbs should be left for 10 to 12 weeks, so they do need planting by the beginning October at the latest. Smaller bulbs can be left for eight weeks.

Once the bulbs show green tips, bring them into the light and allow them to grow on. Then water as necessary. Once the bulbs begin to show bud they can be brought inside and placed in a warm room. 

High temperatures will send them over too quickly, so don’t place them in full sun or in overheated rooms. Moving them somewhere cool, like a porch, every evening will extend the show. Or they can be put into a container, or placed on a plant theatre outside. Forced potfuls of bulbs should be eked out, so that you get a few weeks of flower, so don’t bring them all in at once.

Six-inch round pots are best for larger bulbs and they will normally take six tulips, or six daffodils, or 15 crocus. Hyacinths can be troublesome, developing at different times. In order to prevent this, it is worth potting them singly so that three at a similar stage can be chosen and potted up together. 

Adding pussy willow wands and using small baskets makes them look extra special.  

Forcing bulbs does weaken them, so normally it’s best to throw them out afterwards. The big advantage is that you can time things quite accurately and get narcissi and muscari flowering at the same time, unbattered by wintry weather.  

Generally I avoid forced Paperwhite narcissi, due to their sickly scent and leggy habit.

Good bulbs for forcing

  • Anemone blanda - these raisin-like corms have blue, white or pink long-rayed daisies
  • Anemone coronaria - the black-centred florist’s anemone in bright blues and reds
  • Iris reticulata and Iris histrioides -these make good subjects for six inch pots. ‘Harmony’ is a rich-blue with yellow and white markings
  • Narcissi - any short variety will work
  • Fritillaria meleagris  - particularly good when raised in pots
  • Small crocus - varieties include ‘Ladykiller’ and ‘Prince Claus’
  • Winter aconites - very easy grown in potfuls
  • Species tulips such as Tulipa humilis var. pulchella ‘Persian Pearl’ and T. urumiensis ‘Tity's Star’
  • Tiny blue bulbs including all scillas, muscari and chionodoxa - a perfect for foil for yellow narcissi
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