Planting Bulbs Outdoors

Planting Bulbs Outdoors

To get the best results from hardy bulbs, they need careful and correct planting at the right time of year.

Planting bulbs can provide you with some of the most attractive and undemanding of garden plants. They vary tremendously in size, colour and scent, and also in flowering season — so with a little planning you can have bulbs in bloom from early spring to late autumn.

The term ‘bulb’ is generally used loosely to describe not only true bulbs, such as daffodils and tulips, but also the corms of crocus and gladioli and the tubers of dahlias and begonias Rhizomatous plants like lilies-of-the-valley are also often included together with true bulbs.


planting-bulbs When to plant

Times for planting bulbs can depend on the hardiness and flowering time of the particular bulb.

Hardy spring-flowering types such as crocus corms are planted in autumn. Snowdrops are an exception, however. You can plant them in autumn, but they generally do better planted ‘in the green’ — immediately after flowering in early spring, with the leaves still attached.

Plant daffodil bulbs as soon as they become available — late summer if possible — so that they have the chance to develop a good root system before sending up shoots.

Delay planting hyacinth and tulip bulbs until late autumn or the beginning of winter. This reduces the risk of tulip fire disease and avoids frost damage to hyacinths. Summer-flowering hardy bulbs, such as lilies, can be planted in good weather between autumn and early spring. (Lilium condidum, however, must be planted in autumn.) But wait until early or mid spring to plant the more tender ones — gladioli corms, for example — or frost may damage growing shoots. A good plan is to stagger gladioli planting over several weeks so that you extend their display.


Autumn and winter-flowering bulbs

Don’t forget the value of bulbs that provide colour when it’s most wanted. Colchicum corms, with their crocus-like blooms, settle down well if planted in late summer, even when they’re on the point of flowering.


Planting depth

As a general guideline, plant bulbs in a hole twice their depth — for example, a 5cm (2in) high bulb should be planted 10cm (4in) deep. Lessen this depth on heavy soils but plant more deeply on light sandy soils or where you want bulbs naturalized in grass.

There are, of course, exceptions — namely lilies and cyclamen.



Many lilies produce roots on the stem above the bulb and so need to be planted to a depth about three times the height of the bulb. If you are not sure whether the lilies are stem rooting, cover them with 7.5cm (3in) of soil and add a 5cm (2in) layer of leaf-mould on top. However, plant the Madonna lily (Lilium candidum) just below the soil surface.

Cyclamen corms should also be planted just below the surface — Cyclamen hederifolium should be set so that the tips are just above the soil level.


Tops and bottoms of bulbs

It is advisable when planting bulbs, to always plant them growing point up, and base (where the roots grow from) down. It is usually easy to distinguish between the two — if not, it will not matter a great deal. The woody tuberous roots of anemones and winter aconites, for instance, have no obvious top and bottom, but they pull themselves around in the soil to face the right way. Cyclamen corms can present a problem: if you are not sure which end is which, look carefully for signs of old or new roots from the base.

With all bulbs, make sure that the base is firmly bedded in the ground, taking particular care when planting bulbs for naturalization that there is no air pocket left between bulb and soil. Specially designed tools — a narrow bulb trowel, dibber or bulb planter — make the job easier.


Spacing bulbs

Spacing depends on the effect you want. In containers, place bulbs as close together as you can without actually touching. In beds or borders, natural-looking groups or boldly planted clumps are most striking — don’t dot bulbs about. Small bulbs, such as miniature daffodils, are best planted quite close together, about 5cm (2in) apart. Larger bulbs, for example daffodils and tulips, need about 15cm (6in) between plants and lilies even more — about 25cm (10in). For naturalized planting, space bulbs randomly.


Massed bulbs

The stunning effects of massed spring bedding schemes — a familiar sight in public parks — rely on bulbs flowering at more or less the same time. Even in a relatively small garden you can achieve a similar scaled-down result.

Tulips and hyacinths are among the best spring-flowering bulbs for this purpose. They make an attractive show combined with other plants, for example tulips with dwarf wallflowers or forget-me-nots.

For large schemes like this, prepare a sunny bed well in advance, adding a layer of compost if the soil is poor. Allow the bed to settle for at least a week before planting. If you’re mixing the bulbs with other plants, put the other plants in beforehand. As a further boost to growth, apply a light sprinkling of bonemeal at planting time.


Planting in borders

Smaller bulb plantings make an appealing feature in borders, rock gardens and raised beds, giving life and colour before annuals and perennials come out, and touches of splendour in summer

Bulbs grow best in borders containing a mixture of shrubs and perennials — the rich manuring in pure herbaceous borders can be too much for them. Prepare the ground as for massed bulbs, and plant in clusters of at least five.


Bulbs in containers

bulb-plants-in-pots Window-boxes, patio tubs and earthenware pots are all excellent containers for outdoor bulbs.

All outdoor containers need adequate drainage holes. A layer of crocks — broken crockery, stones or gravel — at the bottom also helps. The best soil mixture to use is a loam-peat-sand one such as John Innes No. 1.

Space the bulbs evenly at the right depth (twice their height) on a layer of compost. Cover them to within about 2.5cm (tin) of the top of the pot. If you are growing a large number of small bulbs, a shallow layer of grit on top of the compost reduces weed growth.


Naturalized bulbs

For an informal display of flowers, few effects can match a colony of bulbs growing in grass or under trees. Crocuses and daffodils are the outstanding choices for naturalizing, but many others are equally suitable. Whichever bulbs you choose, grouping colours separately usually looks best.

Most bulbs suitable for naturalization like some sun. Many flower before the foliage of deciduous trees is fully developed, while others enjoy the dappled sunlight of woodland fringes or glades. Yet others, such as cyclamen and lilies-of-the-valley, will thrive only in shade. One or two deciduous trees at the bottom of the garden are enough to suggest a woodland environment.

To achieve a truly natural effect, throw down a handful of bulbs and plant them where they fall. If you are naturalizing a fair number, a bulb planter is useful. For very large areas, cut and peel back the turf with a spade; fork over the soil before placing the bulbs, filling in with compost and folding back the turf.


Lifting and storing

Although many bulbs can be left in the ground from year to year, lift tender bulbs — freesias, gladioli, acidanthera, ranunculus, sprekelia and tigridia — at the end of the season. Bulbs removed after flowering and replanted in spare ground to leave room for other plants must also be lifted once their leaves have died down.

When leaves and stems have shrivelled, use a fork to lift the bulbs, taking care not to pierce them. Remove dead leaves, stems and old roots and detach bulblets, which you can use for starting new stock for the next season. Make sure that the bulbs are thoroughly dry before storing them in a cool, dry, frost-free place until it is time to plant them out again next year.

19. November 2010 by admin
Categories: Bulbs and Corms, Plants | Tags: | Comments Off on Planting Bulbs Outdoors


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