Wednesday, June 13, 2012

Lily Bulbs not buried deep enough? What to look for...

No, those are not larvae from an insect or other varmints  clinging to the side of this lily stem, but are immature "stem roots".  If bulbs are not planted deep enough to produce roots underground between the top of the bulb and the soil surface - as in this potted specimen - the bulb will have a hard time taking up enough nutrients to survive.

Encouraging the formation of stem roots after planting should be your most important, immediate goal. These critical roots need nutrients within the top 2 or 3 inches of soil - where a top-dressing of fertilizer, compost or well-rotted manure can be placed and where nature provides nutrients in the wild.

Stem roots are far more important than roots grown each year from the bottom of the bulb which helps to anchor the stem against wind.

This stem was found while weeding yesterday. Only one out of perhaps 5000 bulbs in the row was not planted deep enough and the stem roots were valiantly trying to grow using only air moisture to survive.

When the temperatures begin to rise and the humidity drops, these roots would die if not immediately covered with soil.  You can also gently dig the bulb and place it deeper - but be careful you do not break the bulb from the stem or you've defeated your purpose.

The same bulb in the row - note the red arrow showing the proper depth.  It is easy to see how deep the bulb should have been planted, the stem is dark colored where the roots emerge on this variety.  The same variety in the background is all green above ground, because the bulb was planted at the correct depth.  Lilies with naturally dark colored stems are not as obvious, so you'll want to pay close attention.

If you choose to simply pile more soil around the stems, be sure that you provide enough bulk, so the soil doesn't dry out too quickly and stunt the root development even further.  If the lilies are in an individual container, pot them into a larger, deeper pot immediately.  If in a "community pot" that is too large to transplant, your options are limited, but do try to pile more potting soil around the stem.  Compost or well rotted manure such as PooPeas™ mixed with the soil will help to maintain moisture and provide nutrients - one of the reasons we encourage a second fertilizer application when the buds are beginning to open and/or a mid to late summer feeding of manure or compost around the stem. (When we pot up lily bulbs, we use containers that are at least 8 inches deep, with the bulb only an inch or so from the bottom of the pot so that there is plenty of room for the stem roots.  Figure one full gallon of soil per bulb.) 

Planting your bulbs deep enough will also encourage natural division.

Lilies also grow "bulblets" along the underground portion of stem, so if bulbs are planted too shallow, you are also restricting your bulb's natural ability to propagate and make new flowering size bulbs.

Not all varieties will easily make bulblets; by their vary nature, Oriental and Oriental-Trumpet (Orienpet ) Hybrids make only a few each year on stems, but Asiatic lilies can be quite prolific.  Each of those little Asiatic bulblets shown in the above photo can be flowering size in two years.

Asiatic lilies need to be divided every three years on average but Oriental hybrids may not need to be separated for three to five years because they grow slower, hence their more expensive cost in catalogs.

Also see Blog posting  Stem roots in Containers

UPDATE 6.18.12 - Just received this photo from a customer in Texas, look at the bulblets forming above ground on the variety 'Triumphator'.  Usually, they are always tucked in between the stem roots, but it looks like the cells formed into bulblets instead.   It was reported that the weather has been humid, so probably the reason the little bulblets are growing well and not drying up.  This is probably a "one time only" occurrence!

Our advice for this fall:  "I would wait until the leaves have turned yellow, then cut the stem off ground level and also just above the bulblets.  Then simply dig a trench 3 inches deep in your garden and lay the entire thing on it's side and cover with soil.   The bulblets will continue to feed off the old stem and become larger.  Leave them to grow in place next summer and in the fall of 2013, you would then be able to transplant them further apart.  Because of it's Easter Lily heritage the larger bulblets might grow large enough to have a flower in the summer of 2014.    Don't forget to plant Mama bulb deeper this fall..."

No comments:

Post a Comment