Indoor Gardening: Growing Bulbs for Year-Round Color and Fragrance

More and more people are discovering the pleasures of indoor gardening—not only those in town flats without balconies, but those with gardens too.

Keeping a room supplied with cut flowers brings the garden indoors. But cultivating house plants and making miniature gardens in bottles and containers is even more satisfying.

FORCING BULBS

Bulbs grown indoors give special pleasure—their development can be watched from start to finish, and blooms appear when garden flowers are scarce. They're showy, beautiful, and often delightfully fragrant.

For forcing, choose bulbs that are solid, heavy, and free from blemish or mildew. They needn't be top size, but ensure tips are undamaged and thin outer skins (tunics) are reasonably intact. Be especially careful with tulips—skinned bulbs may have been roughly handled; they'll do fine in a garden but avoid them for indoor growing.

Choose bulbs specially treated to flower at certain times. A bulb normally requires a long cold period after planting, followed by warmth for flowering. By artificially simulating these conditions through heat or cold treatment, growers vary the waiting period, dictating when a bulb will bloom. This enables shipping bulbs worldwide and lets indoor gardeners buy bulbs prepared to flower early (e.g., Christmas) or at specific spring/early summer times.

PLANTING BULBS

Bulbs may be forced in many containers with various growing media.

Beginners often use flower pots with soil; guard against over-watering by placing crocks covered with leaves over drainage holes. Bowls made for bulb-growing use bulb fibre or medium-grade sedge peat. One or two charcoal lumps at the bottom of each bowl provide drainage. For crocuses, special terracotta pots with holes punched around the sides work well—fill gradually with fibre, poke crocus corm tips through each hole from inside as you go, plant several more on top. Each pot holds about a dozen corms and makes a delightful picture when flowering, with blossoms around the sides and on top.

Most bulbs grow in soil, compost, bulb fibre, sedge peat, vermiculite, water, brick rubble, or even wet newsprint.

The chief essential: maintain even moisture. Planting material must never waterlog or dry out. Food is less critical—bulbs usually store enough to reach flowering.

If using soil, John Innes potting compost No. 1 gives excellent results. Alternatively, mix equal parts sifted loam, coarse sand, and peat. Soil must be firm but not hard-packed.

Bulb fibre can be mixed at home from sedge peat, crushed charcoal, and oyster shell. Most nurserymen sell ready-mixed fibre at reasonable prices; some brands include a trace of fertilizer.

Soak fibre before use so only a few moisture drops can be expelled when squeezed—never let it swim. Half-fill container, stand bulbs in place close but not touching. Using a wooden spoon handle, pack more fibre around bulbs until smaller ones are completely covered and only hyacinth/narcissi necks show.

Don't twist bulbs to set them lower—this consolidates fibre beneath so roots can't penetrate and grow upward over the rim. Fibre, like soil, should be pressed firmly but not packed hard.

Compost from old newspapers is excellent for hyacinths. Newsprint contains cellulose and naturally holds moisture. To prepare: soak newspapers well, shred into pea-sized pieces. Use in bowls like fibre.

PLUNGING BULBS

When all bulbs are planted, put them in a cold, dark place for 8-10 weeks to encourage good root formation—without this, there's no success. Most bulb failures come from bringing bowls too early into light and warmth.

Ideally, plunge bowls under a 6-inch layer of wood ashes, sand, or soil in the garden. Wrap first in polythene to prevent scratches and heavy rain flooding.

If no garden, stand bowls in a cold, dark place like a cellar or cool cupboard. Wrap in black polythene to exclude light and prevent drying. Wrapped bowls won't need watering during plunging. If unwrapped, check occasionally and water to keep fibre just moist.

Examine bowls periodically. When shoots are about 1 inch high, root growth is strong enough to bring in. Remove polythene, place in a light, cool room at ~50°F (10°C).

Keep bowls covered with newspaper the first day to accustom white shoots to light. They'll green and grow vigorously, but don't move to real warmth—above 60°F (16°C)—until leaves are well out of bulbs. Then water more frequently; frequency depends on room heat. Keep fibre moist to touch but no wetter; over-watering hardens the top (repelling moisture) and dries underneath.

Good idea: sprinkle container with Agrostis tenuis grass seed directly after leaving plunge bed or cupboard. By flowering time, soil/fibre surface will be hidden by a green turf carpet.

COMMON CAUSES OF BULB FAILURE

1. Insufficient time in plunge bed/cupboard → stunted growth
2. Leaving bowls in a draught → yellow leaves
3. Insufficient water at roots → dead blooms on spike, stunted stems shorter than leaves, dead foliage
4. Insufficient light → long, lanky, yellowing leaves

GROWING BULBS ON WATER

A few bulbs—notably crocus, Narcissus 'Cragford' and 'Paper White'—can grow entirely on water. Bulbs must be kept just clear of water (contact causes rot) so roots go down for moisture. No need to keep water-grown bulbs in darkness—development can be watched daily.

Two methods: bulb glasses (restricted neck where bulb perches, roots down to water below—always keep a charcoal lump in the glass) or washed pebbles in bowls/saucers with water at bottom, bulbs lodged between stones keeping them clear of water.

Rain-water gives better results than tap-water; even in a flat, trap rain-water in a container on a window ledge. Top up with rain-water too.

BULBS FOR FORCING

Hyacinths: Most large-flowered force well in white, red, yellow, pink, blue. Roman hyacinths bloom earlier, smaller, daintier, multiple spikes per bulb; usually white, but deep rose-pink 'Rosalie' exists. Plant most hyacinths September/October.

Muscari: All need cool conditions.

Daffodils and narcissi: Recommended: Golden Harvest, Carlton (clear yellow), Verger (white and lemon), Valiant Spark (orange and yellow). For pebbles: Cragford, Grand Soleil d'Or, Paper White.

Tulips: Most double tulips force. For singles, choose those listed as single early in catalogues. Potted September/October, flower January/February.

Crocuses: All can be forced.