Allium Plant Care Guide: Tips and Tricks for Healthy Growth

Alliums are a gorgeous addition to any garden but caring for them properly is key to helping them thrive. In this comprehensive guide we’ll walk through everything you need to know to grow healthy, beautiful allium plants.

Choosing the Right Allium Variety

With over 750 species, the allium genus contains a diverse range of plants. Some popular varieties include:

• Giant alliums like Allium giganteum with huge volleyball-sized blooms on 4-6 foot stems.

• Smaller types like Allium moly that only reach 10 inches tall.

• Delicately nodding blooms like Allium cernuum.

• Ornamental onions like Allium neapolitanum with clustered white flowers.

Consider the mature size, bloom time, hardiness zone, and color to select the right allium for your needs. Larger varieties make excellent statement plants while smaller types can be tucked into borders.

Selecting the Perfect Site

Location is critical for healthy alliums. Choose a spot that provides:

• Full sun: Most alliums need at least 6 hours of direct sun daily for the best blooms. Morning sun is ideal.

• Well-draining soil: Allium bulbs will rot in wet, poorly drained soil. Add compost to improve drainage if needed.

• Neutral to slightly acidic pH: Ideal soil pH is between 5.5-6.5. Test soil and amend if needed.

Avoid planting alliums in low spots or areas that collect standing water after rains. Give them plenty of room to reach maturity without being crowded.

Planting Allium Bulbs

Spring and fall are ideal times for planting allium bulbs. Follow these tips:

• Plant bulbs in early fall about 4-6 weeks before first frost. Spring planting can be done as soon as soil thaws.

• Dig holes 2-3 times as deep as the bulb’s height. Place bulbs pointy side up in holes.

• Space bulbs 6-8 inches apart depending on variety. Follow pack spacing guidelines.

• Cover bulbs with soil, water thoroughly after planting, and add mulch.

Large allium bulbs may need to be planted 8 inches deep. Set the plant marker at the side so you remember where bulbs are located.

Watering Needs

Alliums need about 1 inch of water weekly during the active growing season in spring and summer. Here are some key watering tips:

• Water thoroughly after planting and provide 1 inch of water weekly if rain is lacking.

• Avoid overhead watering to discourage foliar diseases. Instead, water at soil level.

• Reduce watering once foliage starts dying back in summer. Allow soil to dry between waterings.

• Don’t water dormant bulbs in winter. Resume watering when growth appears in spring.

Too much moisture when bulbs are dormant can easily cause rot. Allow soil to dry between waterings.

Fertilizing Your Alliums

Apply a balanced fertilizer when foliage emerges in spring and again when flower stalks appear. Use an all-purpose 10-10-10 or bulb fertilizer. Follow product instructions for proper dilution and application rates.

Discontinue fertilizer after flowering finishes. Fertilizing dormant bulbs can damage roots. Resume fertilizing when growth resumes next season.

Controlling Pests and Diseases

Alliums are relatively pest and disease free. However, watch for:

• Bulb mites – Causes distorted growth. Discard damaged bulbs.

• Fungal diseases – Ensure good drainage and avoid wet foliage.

• Onion thrips – Causes foliage damage. Use insecticidal soap.

• Voles and mice – Use bulb protectors to discourage gnawing.

Rotate planting sites annually and remove any diseased foliage promptly to prevent spreading issues.

Deadheading and Pruning

Deadheading or cutting off spent blooms isn’t necessary but can help tidy up plants after flowering. Leave foliage in place until it dies back naturally. This allows leaves to photosynthesize and strengthen bulbs.

In fall, prune foliage back once it browns fully. Add compost around bulbs to replenish nutrients.

Digging Up and Storing Bulbs

Allium bulbs can be left undisturbed in garden beds for many years. But to control spread or access bulbs for other uses:

• Allow foliage to die back completely after bloom period ends.

• Dig bulbs gently with a garden fork, taking care not to damage.

• Allow bulbs to dry in a shady, well-ventilated spot for 2-3 weeks.

• Remove excess soil and peel away outer scales. Discard any damaged bulbs.

• Place bulbs in breathable mesh bags with peat or vermiculite.

• Store in a cool, dry spot around 65°F until planting time.

Always handle bulbs gently to avoid bruising. Check stored bulbs occasionally for any signs of mold or damage.

Dividing Overcrowded Alliums

Mature allium clumps should be divided every 3-4 years. Follow these tips:

• Dig up entire clump carefully in fall after foliage dies back.

• Gently pull bulbs apart into smaller sections. Small offset bulbs can be replanted too.

• Replant choice vigorous bulbs in the original spot.

• Plant divided sections in other parts of your garden to expand plantings.

Dividing overcrowded alliums will rejuvenate growth. Share extras with gardening friends!

Growing Alliums in Containers

Many small and dwarf allium varieties adapt well to containers. Follow these container growing tips:

• Choose a container at least 10-12 inches wide with drainage holes.

• Use a quality potting mix, not garden soil which may be too heavy.

• Plant bulbs close together, leaving just 2-3 inches between bulbs.

• Place containers in full sun. Rotate occasionally for even growth.

• Water when soil surface is dry to the touch. Drainage is critical.

• Move pots to a protected spot in winter or bury in garden beds.

Refresh potting mix annually. Divided bulbs that outgrow pots can be replanted in garden beds.

Enjoying Allium Blooms as Cut Flowers

Allium’s unique, spherical blooms make gorgeous cut flowers. Follow these tips for the best results:

• Choose allium stems once the lower third of flowers have opened.

• Cut stems when blooms are open using clean, sharp pruners or knife.

• Place freshly cut stems immediately in water. Slice stems again underwater.

• Change vase water daily and recut stems every 2-3 days.

• Remove any flowers that fade to prolong vase life.

Allium’s long-lasting blooms will bring unique beauty to indoor arrangements!

Following these allium planting, care, and maintenance tips will help you be rewarded with vigorous plants and spectacular blooms. Just provide well-drained soil in full sun, moderate watering, and yearly division for success growing allium.