How to grow bulbs
credit: marc falardeau
One of the busiest seasons for planting bulbs is about to begin and for the secrets of a brilliant display, who better to ask than Chris Ireland-Jones, owner of Avon Bulbs, who has notched up an impressive 25 gold medals at the RHS Chelsea Flower Show.
Bulbs are perfect for small gardens: they are often small, they can be squeezed into tight spaces and, although they don’t individually flower for very long, the season they collectively cover can be extensive and includes times when little else is flowering, such as the autumn and early spring. They are not very expensive and the choice is vast.
Choose bulbs that suit your light levels. Roof terraces and balconies may be sun traps, or they could be very shady due to the surrounding architecture. Small gardens could be hemmed in by tall walls or hedges.
If yours is a shady garden (and remember that many bulbs are going to be in leaf early in the year when the sun is low in the sky) choose bulbs that will cope. These include: blue-flowered Anemone blanda, Brimeura, Scilla bifolia, Erythronium and some Ornithogalum (Star of Bethlehem). Unsuitable bulbs grown in too much shade will grow tall and flop over.
For sunny spaces and places where shrubs will not yet have leafed up, there are many more possibilities. Good options include: Anemone blanda ‘White Splendour’, Muscari (grape hyacinths), most Scilla, dwarf species Tulips, most of the Greigii Tulips, Ipheion, shorter daffodils such as ‘Topolino’, ‘Jack Snipe’ and ‘February Gold’ and Triteleia.
Choose big bulbs as they will provide more flowers. Species tulips such as Tulipa tarda, for example, are generally sold at 6-7cm or at 7-8cm (a measure of circumference). The former will produce three or four flowers; the latter, for a small increase in cost, will produce double the amount. So a ‘bargain’ may not be quite what it seems.
Caring for bulbs
Bulbs tend not to need very much feeding: while they are in leaf, they store up starches to make it through the next period of dormancy and many come from parts of the world where the soils are not hugely fertile. Drainage is more important. If your garden soil is really heavy and compacted, dig it over to add air spaces; add humus if possible, which will tend to keep those spaces more open and then, under the bulbs that are being planted, put a cushion of coarse gravel about 1-2 cm thick – this should help to keep the area around the bulbs drier. In containers, we would always encourage folk to use composts that are soil-based and free-draining. The John Innes composts should fit the bill, although you may need to add some slow-release fertiliser in the second and third years as the nutrients become depleted.
Free-draining soils also freeze less readily. This is important because the little bulbs (and their roots) are squeezed and mangled by the freeze-thaw process and, when they are able to grow again, they may well have lost their anchorage and feeding mechanisms. In extremes of weather, do try to protect exposed pots.
Most bulbs start early into growth (using that starch stored in the bulb to get going) but once they have flowered they also disappear again quite quickly. So once you’ve enjoyed the display, remember that, for a bulb, the period between flowering and going dormant again is critical – how it fares in this phase will affect how well it will flower next time around. The longer it is in leaf and the better its ability to photosynthesise, the more ‘weight’ it will put on and the better the flowers. So don’t cut off ‘untidy’ foliage and resist tying up the leaves on the daffodils: give them time instead. Most bulbs don’t need feeding if the soils are reasonable: if they are not flowering as well, it is more likely that they have become overcrowded or overshaded.
The dormant period
All bulbs have a period of dormancy, when they are at rest, and most of them prefer to spend this in dry soil, so you need to put them in places that meet this requirement. Plant the summer-dormant bulbs (daffodils, tulips, crocuses, muscari etc) under a deciduous bush or tree that will keep the soil dry under its canopy or in a container that can be positioned so it doesn’t get too wet in the summer.
There is a trick that is well worth passing on to those who have bulbs in pots. Once the foliage has begun to die away from daffodils, tulips and other spring bulbs, you can turn the containers on their sides and face them away from the prevailing rain. The soil will slowly dry out and the pots warm up in the sun, and the bulbs in the soil will ‘ripen’ and form a skin. In the autumn, you can turn the pots the right way up, scrape the top of the soil away and replace it with some new compost and let the bulbs grow away again. Given decent soil and a reasonably sunny position, your containers should then do several seasons.