The huge, purple-violet flower balls of giant leeks are enthroned on man-high, slender stems. Viewed from a distance, the voluminous spheres seem to float weightlessly in the bed and on the balcony. In order for the majestic ornamental onion species to keep what its name promises, important framework conditions must be observed. This green guide explains in detail and comprehensibly how you can perfectly care for Allium giganteum in the garden and in the pot.
Table of Contents
location
From June to July, giant leeks boast their opulent spherical flowers in a sunny to shady location. The more rays of sunshine spoil the perennial, the more splendidly the early summer bloom is staged. The shafts, which are up to 180 cm high, are inherently stable and stable. Nevertheless, it is advisable to allocate the stately flowers a sheltered place in the garden, on the balcony and terrace.
Soil and substrate
Like all leek plants, giant leeks thrive as an onion plant. Its handsome stems sprout in late spring from voluminous bulbs that have survived winter deep in the ground. For the soil quality, growth as a geophyte means that waterlogging is very harmful. This is how the bedding soil and pot substrate should be:
- in the bed: moderately dry to fresh, well-drained, rich in nutrients and loamy-sandy
- in a pot: loose, structurally stable, nutritious, with inorganic additives, ideally without peat
- favorable pH value in the garden and pot: 6.5 to 7.5
If the quality of the garden soil or pot substrate does not meet the recommendations, remedy the deficiency with additional additions. You can optimize clay-accentuated, moist bed soil with sand and fine-grain gravel. Lean garden soil receives a well-measured portion of nutrients in the form of ripe compost, bark humus or deposited horse manure. Work in three to five liters of compost per square meter of planting area and add a few handfuls of horn shavings. You can enrich conventional potting soil with lava granulate, expanded clay or sand. Peat has long been taboo in natural gardens. Home gardeners ignore substrates that contain peat in order to contribute to the protection of our natural moors. In any case, potting soil with a high proportion of peat tends to compact, which giant leeks do not like.
Plants in the bed
The best time to plant Allium giganteum is in late autumn. The ideal time window opens at the beginning of November. Spring onions planted too early in the ground could sprout prematurely, especially in warm, sunny weather. How to plant giant leeks correctly:
- Loosen the soil deeply, remove weeds, thick stones and old roots
- dig a 25 cm deep pit for each onion
- Enrich the excavation with compost, if not already done during the soil preparation
- Plant spacing is 30 to 40 cm
- Cover the bottom of the pit with a layer of sand as drainage
The perfect planting depth corresponds to twice the bulb diameter. Fill the planting hole with soil, which you press down with both hands for a good connection to the soil. Water the planting area with a fine shower so that no soil is washed away. A layer of leaves and brushwood is advantageous for the coming winter to protect against severe frost and permanent winter wetness.
Plants in the pot
From the beginning / middle of March, balcony gardeners plant giant leeks in a pot with a minimum height of 30 centimeters and a floor opening as a water drain. Drainage made of potsherds, pebbles or expanded clay effectively prevents the formation of waterlogging. So that the substrate does not clog the water-bearing layer, please place a fleece over it. This is how you plant giant ornamental onions in the pot in an exemplary manner:
- Fill the pot halfway up with substrate
- Plant the onion to a depth of 20-25 cm
- Fill in the rest of the soil up to 1 or 2 cm below the edge of the pot
Press down the potting soil and water with normal tap water until it runs out of the opening in the ground. If you are growing giant leeks in a pot with a saucer, please check after a quarter of an hour whether water has accumulated. To prevent waterlogging from this, pour away the excess water. Resourceful gardeners lay out the trivet with grit, stones or expanded clay as an additional bulwark against fatal waterlogging.
pour
One of the many advantages of Allium giganteum is its tolerant attitude towards lime. Last but not least, you benefit from this with regard to the water supply. No extensive measures are required to collect rainwater or decalcify tap water. The advantageous lime tolerance allows giant leeks to be poured with normal tap water.
How to do it right:
- Keep the garden soil and pot substrate slightly moist
- Determine the water requirement once or twice a week (daily on hot days) with a finger test
- Press the index finger or thumb 1 cm deep into the earth
If you do not feel any moisture in the upper layer of soil, your giant ornamental onion would like to be watered. There is more need for watering in the pot than in the garden. Let the water run directly onto the root disc. Avoid puddles forming in the bed, which can cause damaging waterlogging. Water on potted plants until the saucer fills up. Any watering water that has accumulated in it should be poured out after 10 to 15 minutes.
Fertilize
In the year of planting, there are sufficient nutrient reserves in the garden soil and pot substrate. From the second year of standing, you fertilize giant leeks in the bed once a year with compost or bark humus and horn shavings. The best date is in autumn, so that busy soil organisms have processed the organic material so that it is available for plants by spring. Rake in the fertilizer on the surface and pour in more.
Giant leeks in the pot benefit from liquid fertilizer, which you add to the irrigation water from March onwards. The supply of nutrients ends at the end of July so that the plant can mature before winter.
To cut
After the flowering period, Giant Leek adds decorative accents with filigree, golden-brown fruit clusters for a while. Then it is time to prune the perennial at ground level. Please wait until all parts of the plant are completely absorbed. During the wilting process, the plant creates important nutrient depots inside the bulb. Allium giganteum rests in its bulb as a survival organ until the beginning of the next growing season.
Winter in the garden
In the protection of the garden soil, giant leeks overwinter safe and sound without any special precautions having to be taken. A protective layer of leaves, brushwood or compost is advantageous in regions with no winter or in the year of planting. The hardy perennial cares little when temperatures drop well below freezing. A well-established plant is reliably frost-resistant down to – 17 degrees Celsius.
Winter in a pot
In the pot, giant ornamental onions cannot fall back on a resilient frost resistance, as in the garden soil. The exposed position of substrate and bulb makes the perennial vulnerable to severe cold. How to properly overwinter Allium giganteum in a pot:
- Before the onset of winter, cover the vessel with jute, fleece or bubble wrap
- Slip a block on styrofoam or wood
- cover the substrate with leaves, straw or bark mulch
A change of location to the partially shaded, sheltered wall niche is recommended. Full winter sun could warm the pot and cause it to sprout prematurely. Not until March does the large ornamental onion take its usual place in the sun again and is freed from winter protection.
Multiply
In the course of the growing season, each giant leek onion strives for numerous offspring. For this purpose, each healthy mother onion creates several daughter onions. You can give free rein to the natural process and enjoy fresh flower stems. Over the years, a dense clump with numerous flower balls forms in the bed or pot.
Alternatively, you can use the bulbs for targeted propagation. Dig up an onion in the fall. Cut off the easily visible daughter onions with a sharp, disinfected knife. Dust the cuts with rock flour or charcoal ash. Plant the mother onion again. Alternatively, you can plant the daughter bulbs in the soil at the new location. Breeding is more promising if you nurse the bulbs in pots for one season and only plant them out in autumn of the following year. There is nothing to worry about if the first flowers show up after three years.
Diseases
In the sunny location in well-drained soil, you will not have to complain about diseases on giant leeks. It has been found in gardening practice that pathogenic germs obviously steer clear of ornamental onions. Problems with rot or mold are usually due to mistakes in maintenance. Excessive watering causes waterlogging in the garden and pot. The onion cannot cope with a permanent environment, it softens and rots. Do not pour giant onion according to a firmly cemented schedule, but rather when the earth is noticeably dried out.
Pests
Giant leek is one of the perennials with a natural resistance to pests. Indeed, near-natural gardeners use the onion plant to keep cunning insects and voracious voles at bay. Only aphids do not care about the defensive odor and boldly nestle on leaves and stems. In the early stages of an infestation, you can use a tried and tested home remedy to solve the problem. Mix 1 liter of water with 2 tablespoons of soft soap and add a splash of spirit. Spray the aphid-afflicted giant ornamental onion every 2 to 3 days until all the pests are gone.
Conclusion
A sunny location with nutritious, loosely drained soil encourages giant leeks to have a furious flowering period. So that the magical spherical blossoms float through the garden, the onion is placed 20 to 25 cm deep in the earth. Watering when it is dry, fertilizing with compost in the garden and liquid fertilizer in the pot round off the uncomplicated care program. Cut the retracted flower stems off at ground level. Winter protection is primarily recommended for Allium giganteum as a container plant.
