Why do some new roots fail?

[snowbell]

Hello


I am growing Phalaenopsis species seedlings on my windowsill.

My Schilleriana was growing two new roots into the media, but one of them suddenly shriveled up entirely. The other keeps growing fine.

My cornu-cervi is growing many roots, but the growing tip on one shriveled away.

Is this normal, or a culture issue? Would it help if I watered the seedlings with CalMag and kelp instead of fertilizer?

Thank you!

[Bayard]

I ask myself this question all the time - still don’t know why it happens.

[estación seca]

Welcome to the Orchid Board!

Phal. roots like being warm and humid. There are usually some damaged roots in the lower humidity of homes. If the roots in the medium are OK the plant doesn't mind.

[K-Sci]

Potential causes:

When a droplet of dilute fertilizer remains on a root tip after fertilizing it will become highly concentrated as the drop evaporates. A high concentration of fertilizer can burn the root tip. Fertilizer solutions that remains in the crown of a plant after fertilizer can also become sufficiently concentrated to burn.

As water evaporates from sphagnum, fertilizer, chemicals, and hard water minerals can become so concentrated on the surface of the moss that root tips die when the touch the moss. This is the likely cause when many, most, or all roots die right after they touch the top surface of the moss.

Intense sun or artificial light can warm a root tip sufficiently to kill it. The tips that die can be only those receiving the stronger light.

Pests such as scale, thrips, and mealy bugs can be present in very low numbers. Most pest varieties only thrive on host plants of a particular characteristic/genus/species. Varieties not well-suited to feed on orchids may be present in numbers too small to be otherwise noticed.

Mechanical damage can occur when the plant is handled. The damage may not be visible and root tips can be easily bruised.

If it doesn't happen often, it isn't cause for concern. If all or most roots fail, then there is a problem that needs to be identified and corrected.

-Keith

[K-Sci]

Originally Posted by snowbell

Would it help if I watered the seedlings with CalMag and kelp instead of fertilizer?

I see this second part of your question has been neglected. The short answer is "no". Now, the long answer.

You didn't say what fertilizer you use, but MSU 13-3-15 is a good choice if you use very low mineral water such as reverse osmosis, distilled, or rainwater. MSU 19-4-23 is a good choice if you use tap water that provides the necessary nutrient calcium. The MSU 13-3-15 includes calcium. MSU 19-4-23 does not. You should only use CalMag to supplement your regular fertilizer if you have low mineral water and are not using a fertilizer such as MSU 13-3-15 that provides calcium.

Orchids can be fertilized with the solution mixed at the label strength, but a weaker solution is generally recommended. If you are growing in an indoor environment with air conditioning/heat, fertilizing weekly with 1/8 tsp/gallon is a good choice. If you fertilize bi-weekly, 1/4 tsp/gallon is comparable. My orchids are grown at outdoor Mississippi temperatures, which often approach 100F in the summer. I use twice the amount I suggested for indoor orchids. Ray (or using his calculator at firstrays.com) can help you fine tune fertilizer amounts, though fine tuning isn't necessary.

With few exceptions, orchids will thrive with amounts considerably above and below the amounts I suggest. If you apply a bit too much nitrogen, the leaves of your phalaenopsis may develop a bit of a longitudinal irregularity wave rather than hardening off with a relatively uniform lengthwise arch or flat. In my experience phals that harden off with irregular leaves grow and flower fine.

Using kelp supplements will not prevent root burn and in my opinion there is no benefit whatsoever to using most kelp fertilizers or supplements. I make an exception for KelpMax/Kelpak (same product) because I've conducted experiments that tested its effects.

In my experiments, I conclusively showed that Kelpak stimulates root growth and causes orchids stems to branch/fork more freely. In my experiments overdosing Kelpak often resulted in extreme root growth and most of the single lead plants I treated branched 2 and often 3 ways. I don't recommend overdosing Kelpak because the new leaves were often stunted, possibly because very high doses of Kelpak push root and shoot growth beyond what the plants biological machinery cansupport. Normally, I use Kelpak at the label rate once per month on all my orchids.

I should also say that you don't need to use Kelpak for your orchids to thrive and I can't say that orchids will flower better using this product. Induced vegetative growth may increase flowering, but it may also reduce the energy available for flowering. I've seen some evidence that overdosing results in the latter.

The one use for Kelpak I've found indispensable is promoting increased root growth when trying to establish back-bulb divisions or re-establish plants that have suffered serious root loss. In my experiments Kelpak didn didn't work for completely rootless orchids.This could be because rootlessness prevents sufficient uptake, or it could be that the old bulbs just don't have the necessary energy.

Kelpak can be purchased at firstrays.com. You will also find a plethora of superlative orchid growing information on Ray's site.

-Keith

[jje10001]

Originally Posted by snowbell

My Schilleriana was growing two new roots into the media, but one of them suddenly shriveled up entirely. The other keeps growing fine.

This is an issue with my schilleriana as well; for some reason, its root tips can occasionally fail and shrivel up, and it seems to prefer sending out new roots horizontally in the top layers of its medium (even though the medium is practically brand new).

I am getting the message that it really does prefer being mounted over being potted...