You know, sometimes they just don't produce roots for months on end. They will eventually. Don't fear :-) I wouldn't recommend potting without soil. It really works better for me to just pot them in soil and provide a lot of bottom heat. Then you just check them again after about a month or two.

I often see "bottom heat" recommened for root development and wonder if it really makes any difference. I have about 80 bulbs and they seem to make good roots at 52-58 degrees without bottom heat, even better than the ones I start in the house where it is warmer. They seldom shrink down. It seems to me they root very well at cool temps. Are there experiments on this done by someone? I know seeds germinate better with bottom heat and while the increase in temperature helps there, I wonder if the bottom heat doesn't drive the moisture up to the seeds and that is one of the main reasons bottom heat helps on seeds. I am not sure it helps on amy bulbs. Does anyone know of any studies on this? I see it recommended all the time.

Yes, bottom heat absolutely makes a difference in promoting root growth! Whenever I have bulbs or bulblets without roots, I place them on my heating pad, under lights, and they root a lot faster than if I just set them on a windowsill.

I also use a rooting hormone powder to help. Between the extra heat and the powder, I'm assured root growth faster than if I didn't use anything. I've always done this to help in root production... seeds, cuttings, and now with bulbs... and I can attest to the quicker formation of healthy root systems.

Commercial greenhouses use large heat pads to promote faster root growth... especially here in the north. They help extend the growing season, giving plants a better head start.

Since bulbs are primed to bloom by the growers, I never worry about cutting off scapes or trying to get root production first. I pot up all new bulbs in medium and let them bloom or grow leaves, whichever they prefer... I know that eventually the bulbs will grow roots and begin their own cycles. Stubborn bulbs that are too slow to grow roots will be placed on my heat pad, and guaranteed, root growth will start shortly thereafter.

Hi there,

Now I am not an authority on hippies, or anything really for that matter, but my experience is that with a lot of plants the temperature of the soil is a big factor in how their growth goes, both roots and the parts you can see. I too use a heat mat when rooting things after some experiences rooting Thanksgiving cacti. Cold soil equals rot for a lot of plants. I would think that hippies especially would be the same since rot seems to be their nemesis. It would be good for someone to research this, but it would be hard to get a bunch of rootless bulbs that you knew were really in the same condition as each other, so it would be hard to tell if a difference was because of how the bulb was grown previously or the current rooting temps. They'd have to be bulbs you knew! Also, mymanga has 50 degrees on her porch, but what is the temp of her soil? We can here have days where the air temp is 50 degree F ( 10 C) in the middle of winter but the ground stays frozen. I hope someone will try this sometime and we can see what happens, but my money is on the people wielding the heat mats!

Barb

My theory is that if commercial greenhouses and growers are using them, there must be something to it... especially since heat mats are rather on the expensive side! I doubt professional growers would invest in such items if they were worthless!

I know they work well for rooting plant cuttings in a short amount of time, helping seeds germinate quicker, and from what I've seen, they work the same for bulbs. By heating the soil to a warm and pleasant temperature, you're emulating spring or summer conditions, which is when most growth occurs.

As Barb mentions above, soil that's cold and wet can spell doom for most tender bulbs, and is not an environment conducive to root growth. Add a little bottom heat, and the bulb receives a message that the season is right for growing new roots.

I don't know of any studies done with bulbs, but I'm sure someone somewhere has experimented... I haven't looked, but everything can be found on the internet, it seems... there's probably at least one mention of it to be found through a search.

Anyway... my experiences in growing have shown me that bottom heat is a useful tool in growing roots a little faster than without.