Hello! I live in Chicago, IL in an apartment complex. I have large floor-to-ceiling windows, facing south. The windows are also fully sealed and unable to be opened, which regulates temperature very well. Even in the winter time, my small apartment stays a comfortable 70 degrees F.

Because I live in the city, and Chicago tends to be cloudy throughout the winter, I'm not quite sure if I'm getting enough light for my cactus just by sitting them by the window. I see that they're casting a soft shadow during the day. I've never had issues growing cactus indoors and they look healthy enough, but I have noticed that they almost never grow much larger except a tiny bit during the height of summer. They do flower occasionally in beautiful, brightly colored little blooms, but a couple of the cacti only flower a few bulbs at a time rather than a full crown.

Would the purchase of an artificial grow lamp be worthwhile here, or am I overthinking it? If I purchased an artificial grow lamp, should I increase the amount of watering? Currently for the winter time, I water them once a month. They are potted in well-draining soil with a 50/50 mixture of commercial succulent soil + gravel.

Thank you for the help!

Do 2 things for us:

Read this:
The thread "Artificial light for cacti and other succulents" in Cactus and Succulents forum

And, add photos of your plants to this thread. Knowing what your plants look like is the best way to tell if there's adequate light. Cactus are very opinionated.

Yes, I agree with what Daisyl said. It would help to know the type of cactus, as some cacti are cold hardy, and will survive outside. The growlight type would also be something to consider. IF it produces lots of light and heat, the soil will dry up faster, therefore more watering is needed. Your soil mix seems good.

So sorry - didn't realize I forgot photos! Here are my boys (taken from each side)



*note about the deep pots - these are the terracotta ones I found available for purchase closest to me - the bottom half of each pot is filled entirely with rocks to prevent water from soaking all the way through.

The lamp I was considering is this one on amazon: https://www.amazon.com/dp/B07FM4X64W/

Thank you for the link to the artificial lights thread - I will definitely read through it!

They definitely look healthy. Use growlights to extend the growing season, its not technicaly nescessary. With terracotta and such a well drained soil mix, they definitely will need to be watered more, when under growlights. The hotter, and brighter the light, the more often you will need to water. Its partially trial and error. If they look dehydrated, then water, if they are firm, don't.

The end cacti are Mammillarias, but they all look good to me. If they look that good, why do you care if they grow faster or not? How long have they been under your care?

I get too much summer sun with associated heat sometimes during the summer months - depending on the year. Some of my Mamms have not grown fast and take a break during the excessive heat times. They seem to do more growing in the longer fall days before it gets too cool. Some remain small after several years and I'm happy with that size if they remain healthy. Others grow a bit more. The native Mamm in this area is a small cactus and I've never it grow large or fast under native conditions. That's also true for a couple of other native barrels here. Some of my cacti bloom more readily than others. Some skip blooming at all in some years.

needrain said:The end cacti are Mammillarias, but they all look good to me. If they look that good, why do you care if they grow faster or not? How long have they been under your care?

Did not want to communicate that I am unhappy with the size of the cactus - they are healthy and I have cared for the mammillarias for 3 years, the middle two I just recently purchased. I'm always striving to make sure the cactus are well cared for, and wanted to see if a grow lamp would help them be the best and healthiest they can be!

Radicandy said:

Did not want to communicate that I am unhappy with the size of the cactus - they are healthy and I have cared for the mammillarias for 3 years, the middle two I just recently purchased. I'm always striving to make sure the cactus are well cared for, and wanted to see if a grow lamp would help them be the best and healthiest they can be!

To me it looks like you are doing a good job. I'm not seeing any deficiency in the Mamms after 3 years under your care (assuming you haven't changed locations during that time). I'd love to have your window situation in the winter months, but not when the summer sun would be blasting it. Different locations always have to have some kind of work around for plants depending the specific conditions a grower has to work with. I usually try to discourage active growth in the winter months for most of my plants. The Mamms just seem to like the borderline weather between freezing and late summer. Depending on the winter weather they tend to be at their best if I can manage to handle the usually brief spells of freezing temps. They really don't come indoors much. True for the cacti I have growing. The outdoor light keeps them happy, so I just have to watch for temperature drops.

Your cactus look great. Most cactus aren't the speediest growing plants. I wouldn't worry unless I saw signs of them growing pointy.

On the grow light you linked, I don't see anywhere about how many lumens (or any light measurements). I suspect if you are growing low light tropicals, these lights would suit you but not for the level of light a cactus needs. But, you are adding supplemental light, not supplying all light needs artificially so maybe they would help. I would be wary of any light not listing how many lumens its supplying. The down side to artificial lights are they are very directional - only the plant directly under the light will gain any benefit, anything off to the side will be in the shadows. You may need one light per plant.

The lumens on amazon light products may not be correct, and are often pulled out of thin air. I would not trust the lumens. Best you can do, is to test the lumens yourself with your phone..