Tips for naturalising

Many of our miscellaneous flowerbulbs are suitable for naturalising.

If a bulb plant is to develop to its full potential, (come back and flower every spring) it must be provided with good growing conditions and a suitable niche in the garden where it can remain undisturbed without the need for its foliage to be prematurely removed. It is important for bulbs to retain their foliage after bloom until the leaves die back naturally, and that they are able to enjoy an uninterrupted cold period. 
In the lawn 
Crocus, for example, will thrive for years if planted in manicured lawn with somewhat dry soil. But the foliage must be allowed to develop fully, the grass should not be mowed until the crocus leaves have died back. Even though the grass may still be dormant, there is always the urge to get out the mower and to cut off the foliage immediately after flowering is over, but this should be avoided. The foliage must remain for the bulbs to re-charge themselves through photosynthesis. It is a small price to pay for the beauty and joy of the following year’s colourful spring display.
Once flowering is over, foliage develops more rapidly and often seeds are formed. For the majority of bulbs that develop seeds it is important that they are allowed to mature and ripen naturally, for when distributed in moist rich soil they will germinate freely and rapidly enlarge the colony.
Exceptions: not all bulbous, cormous and tuberous plants that are planted and then left to their own devices will be capable of providing the same fantastic flowering display year after year, or of increasing their numbers as well. Findings generated by extensive research conducted in recent years has led us to the conclusion that many flower bulbs are suitable for perennialising only if planted in a sunny location. Included in these are the familiar Allium, Anemone, Chionodoxa, Corydalis, Crocus, Cyclamen, Fritillaria, Muscari, Narcissus, Scilla, Triteleia etc.. 

There are many locations that can successfully accommodate flower bulbs. Ideally, plantings should be of sufficient size to make a viable display and situated in positions where they can be easily viewed from any angle. Large grassy areas are especially well-suited. In addition, broad mixed borders and shrub plantings all lend themselves to permanent bulb plantings. A wooded area can be considerably enlivened by the addition of sweeping plantings of shade-loving species. 

Soil cultivation 
The soil must be carefully considered when planning to plant flower bulbs. Moisture and humus content as well as acidity or alkalinity (pH) all play an important part in the success of the venture. Drainage should be good and where the humus content is poor, the soil should be improved by the addition of well-rotted organic matter. Heavy loam and clay soils especially benefit from this treatment. The acidity/alkalinity (pH) of the soil should ideally be between 6 and 6.5. It can be increased by adding garden lime or lowered by the addition of peat (which has a very low pH of 4).

Most soils do not require special treatment in order to be suitable for perennialising bulbs. Of course, this is to some extent dependent upon the bulbs that you propose growing and the type of soil and conditions that prevail. Crocus, grape hyacinths and narcissi are particularly suitable for larger grassy areas such as medians, slopes and the areas in front of shrubs. They are very useful for extensive sites where it is possible to plant mechanically.

A customised fertilizing program keeps plants healthy and resistant to pathogens and pests and also cuts down on the use of chemical control agents. Proper fertilizing also ensures a good soil structure.

There is a choice of fertilizing agents:

  • Compost and manure. These are organic fertilizing agents. As described previously, they are also effective in improving the soil.

  • Organic supplements that provide a complementary balance to organic fertilizing agents.

  • Compound mineral fertilizers

The type of fertilizing agent chosen depends on the kind of planting and the time at which the agent can be applied.

When flower bulbs and other plants increase their numbers entirely on their own, this is evidence that they are being provided with a habitat that simulates their natural habitat. In these situations, nature is in balance: the type of soil, its structure, and its drainage perfectly accommodate the needs of the plants. In such a balanced situation, the addition of a fertilising agent is not usually needed.

Sometimes, however, plants display certain symptoms (often visible in their leaves) that indicate a deficiency of a certain nutrient. This is when it would be advisable to apply organic supplements. Because these are organic, they are more suitable for the natural environment in which these plants are located. 

Organic supplements correct specific deficiencies in plant nutrition supplied by organic fertilisers; examples of organic supplements are a phosphorus fertilizer and vinasse (a waste product from the food processing industry that is very high in potassium). Finally, there are fertilisers that contain calcium such as marl (coral-algae calcium) that regulate the pH of the soil. If this type of supplement is used for flower bulbs, it should be applied immediately after flowering.

As a rule, mowing grass strips containing flower bulbs is not started until an average of 6 to 8 weeks after flowering. Grassy areas planted with flower bulbs can be mowed only after all the aerial parts of the bulbs have withered back.