Most hardy bulbs are low maintenance, especially when growing in the ground. In containers, they just need a little extra watering and feeding.
Watering
All bulbs need plenty of water while in growth, and for six weeks after flowering until the leaves die down and they become dormant. Summer-flowering bulbs may need water during hot dry spells.
Very vigorous summer-flowering tubers and rhizomes, such as cannas and dahlias, need regular watering throughout the growing season.
In containers, make sure bulbs don’t dry out during the growing period. When watering, water thoroughly and allow the soil to become slightly damp before watering thoroughly again. The compost should feel moist but not soggy.
See our guide to watering wisely.
Feeding
To promote good flowering next year, feed the bulbs every seven to ten days with a high-potassium fertiliser such as a liquid tomato feed. Begin feeding as soon as shoots appear, and stop feeding once the foliage starts to die down at the end of the season
For bulbs in containers, start using a high-potassium liquid feed, such as tomato fertiliser, in the run-up to flowering. Continue feeding until the foliage begins to turn yellow and die back.
Vigorous summer-flowering tubers and rhizomes, such as dahlias and cannas, benefit from a high-potash liquid feed every two weeks during flowering.
Deadheading
Cut off spent flowers at the base of the flower stalk.
With true bulbs and corms, this won’t stimulate further flowers, but it will prevent the plant wasting energy on making seeds. Instead it will put its energy back into the bulb, for next year’s display.
With tubers and rhizomes, such as dahlias and cyclamen, regular deadheading will encourage further flowering.
Cutting back foliage
With true bulbs and corms, such as daffodils and tulips, you can cut off the dead leaves six weeks after flowering finishes. Wait until it is yellow, straw-like and no longer able to produce food for the bulb. Until this time, continue applying fertiliser and watering as above.
Also, don’t tie up or knot the leaves, as this can prevent the bulb producing flowers the following year.
Overwintering
Hardy bulbs can be left in the ground all year round. Those in containers should be fine too, but can be moved into an unheated greenhouse or cold frame in colder regions which are subject to hard frosts.
Tender, half-hardy and borderline-hardy plants, such as cannas, agapanthus, gladioli and dahlias, can be grown in containers and brought indoors over winter. If you live in a mild area, you could risk leaving them in the ground over winter, covering them with a 20-25cm (8-10in) layer of insulating mulch and removing the mulch in spring as they come into growth.This is only possible on a light free-draining soil, as a heavier clay soil will become too wet over winter and cause the plants to rot. In this instance it is best to grow these plants in containers.
Some bulbs such as tulips, prefer to be kept dry when they are dormant in summer. To provide these conditions they are best lifted, dried off and then stored until autumn, when they can be planted out once more
To lift and store true bulbs and corms:
- Wait until the foliage has died down, then carefully dig up and clean off the loose soil from the bulbs.
- Trim off the roots and the outer layers of loose, flaking tunic.
- Only keep healthy bulbs of a good size as these will be most likely to flower the following year– discard damaged or diseased bulbs.
- Lay the bulbs on a tray to dry for at least 24 hours, to help prevent fungal rots developing in storage.
- Put the bulbs in labelled paper bags or nets and store in a dry, cool place.
Caring for older plants
Clump-forming bulbs can become congested over time, which can reduce flowering. Divide the clumps every few years to keep them vigorous and flowering well.