Why your Seeds aren’t Germinating: Common Mistakes Made Growing Houseplants from Seed, and How to Fix Them
I get several questions all the time asking “I planted my seeds a month ago and I’ve been keeping them brightly lit and the soil moist, why haven’t my houseplant seeds sprouted?” While every houseplant seed variety is unique with it’s requirements, a lot of the setup basics are very similar between say Fire Flash Plants, Polka Dot Plants and Philodendron Selloum, so hopefully this post can help you figure out what could be going wrong.
Before we continue on let me clarify something, if you’re growing seeds from Plantflix, then the seeds have been batch-tested for viability and you can expect a success rate above 85%(above 95% for a lot of the seeds). There will just be naturally occurring duds(non-viable seeds) in just about every packet, though I’ve had some customers have a success rate of 100%! However, if you’re not getting at least a 60% success rate, chances are something’s off with the setup. If you follow the steps outlined in my post explaining How to Grow Houseplants from Seed, then you should see some germination activity within a month. If not, read on to see what could be going wrong! If you’ve followed all the steps, then reach out to me and we’ll get you a replacement :)
Pre-planting Mistakes: Seed Storage:
Seeds aren’t affected as much by the cold, in fact a lot of the time they’ll be stored in a fridge before being sent out, but they don’t keep well in excessive warmth or light. If you’re not planting your seeds right away, keep them stored in a cool, dry place. The ideal setup would be a low-trafficked area away from any vents.
Put your seeds in a ziploc bag to keep out moisture, or keep them in their tins if they came in one
If keeping your seeds for a while, consider using a cooler as a kind of storage box for temperature control
Closets are usually a good place to store seeds
For seeds like Monstera Deliciosa that must be kept fresh, or if you’re storing seeds for a long time, keep them in a ziploc bag in your fridge(they can be kept in a freezer but that’s trickier to pull off successfully)
So this is where the most crucial mistakes happen. Humidity is probably the most important factor to get just right. This isn’t like herb or veggie seeds where they can benefit from extra humidity but most sprout fine even if you slip up a bit. Houseplant seeds are very finicky about this sort of thing! If you let the soil dry out at all, that may kill the chances of successfully germinating the seeds.
You can have some success if you just plant the seeds in a planter and then mist the soil every day for humidity, but oftentimes that’ll result in lower germination rates or possibly even no germination at all! I can’t stress enough, when you plant your seeds, add a plastic covering to your planter(a ziploc bag is perfect for 3” planters, plastic wrap, or a plastic lid if you have a greenhouse).
On top of that, chances are you’ll want to pre-soak the seeds in hot water for 24-48hrs before planting, or you can do what I call the paper towel method to germinate the seeds. Prepare a moist paper towel, place the seeds on the paper towel, roll it up and place it in a ziploc baggie. What I’ve been recommending is pre-soak most of your seeds, but set aside 5 or so to start off with the paper towel method. You can monitor those more carefully, ensuring the paper towel remains moist, and check in on them every few days to see if there’s any germination activity. If there isn’t anything within a month, then chances are there’s something wrong with the seeds and from there we can discuss getting you a replacement.
Finally, you want to be checking in on a regular basis, just because you have a plastic covering doesn’t mean the soil can’t dry out. If it’s starting to look a little dry, water the planter either from the top or from the bottom if you have it on a tray.
On the other hand, do not over-water the seeds. Soil must be moist, not soggy. If you overwater the seeds, you risk the chance of causing rot, especially if the planter has a lid. Again, I can’t stress enough how much better it is for the seeds to have a plastic covering to maintain the right level of moisture in the soil for the seeds.
What to do if you feel this is the issue:
You can still try to see if fixing the setup and giving the proper moisture will get the seeds to germinate. Try sifting gently through the soil to see if you can still find the seeds. If you don’t see any germination activity, then chances are the seeds didn’t make it and you’ll want to try again.
Pre-soak the seeds in warm water before planting them
Start off a portion of the seeds with the paper towel method(moisten up a paper towel, place the seeds on it, fold it up and place it in a ziploc baggie. When the seeds start to germinate, plant them in soil)
Cover the planter in a ziploc bag, plastic wrap, or a dome for humidity.
Check to make sure the soil is moist(not soggy) at all times.
The planter must have good drainage. If the water cannot properly drain, you risk growing mold or fungus, or drowning the seeds and causing rot.
Some planter options:
seed starter trays
reuse plastic fruit/berry trays(provided they already have holes for drainage)
Do not use garden soil! Use fresh and well-draining potting mix or sphagnum moss. Not only does garden soil not contain the ideal composition for tropical varieties, but it is likely to contain various fungi, pests, and diseases that could hurt the chances or you seeds germination. You can even consider bake your soil in the oven to sterilize it thoroughly, it’s an optional step but it can help.
Let the Plants breath:
When you grow your plants under a plastic covering, make sure to let them breath every once in a while. Ideally make sure that you take off the cover every few days, or poke some holes so that you give the plant access to fresh air. They do need the oxygen, after all :) This also lessens the chances of any mold growth.
If you’re noticing a thin layer of mold growing on the surface of the soil, remove the covering for a few hours and you can even lightly sift around the top surface of the soil without hurting the seedlings to allow some fresh air to penetrate the soil.
I write on the directions to give the houseplants “bright indirect light”. If some of you are new to houseplants, let me break that down for ya. If that’s what the directions say, that means the plants cannot receive direct sunlight. So, if you’re planning on growing the seeds by a windowsill, make sure it’s not a south-facing one! Remember, these are tropical plants that grow in the shade under large trees so they’re not equipped to deal with full sun.
Some lighting setups that can work:
A few feet away from a south-facing window, so that the planters don’t actually get any of the direct sun rays but are still in a bright spot.
An east, west or north-facing window can work fine! You’ll still want to be careful that they don’t get any(or at least not much) direct sunlight. In my case, my west-facing window is surrounded by trees, so I know exactly what parts of my window get direct sunlight in the afternoon and which don’t. A little sun chances are wouldn’t hurt, but for safety keep it out.
If you’re growing outside, outdoors in a shady spot is good and can provide quite a bit of light! This is really only a good option in the summer when temperatures are more along the lines of what tropical plants need.
It may sound contradictory, but grow lights are awesome. They lack a lot of those damaging rays or heat from the sun but manage to give the necessary light for the seedlings to thrive, so growing under grow lights is actually probably the best thing you can do for the seeds.
The seed directions specify that the seeds must be kept warm. This is crucial, it extends to making sure that the soil medium you’re planting the seeds in isn’t too cold. So, if you’re moistening up the soil, it’s preferrable to use warm water. The warmth will stimulate germination, whereas the cold will stimulate dormancy.
To err on the side of caution, use warm water to moisten up the soil instead of cold water.
Keeping the seeds away from vents or windows that cause drastic temperature differences.
This one’s dependent on where you live, but if it gets below 50F or above 90F on a consistent basis, keeping the seeds in a spot in the house that is air conditioned or heated to keep the temperature around them consistent.
To be safe, get a thermometer/humidity reader so you know what conditions your plants are growing in.
Having a plastic covering can help keep temperatures more consistent and just higher in general, which aids in germination.
These seeds are more picky than the adult plants, so you must must make sure temperatures stay at at least 65F and optimally somewhere from 70-90F(this depends on the variety and I have the temperatures specified ).
The best thing you can do for your seeds to get them the proper temperature is to get a heat mat and set it to the temperature that a particular seed variety requires. That way you can make sure there isn’t as much variation in temperature.
Well, that covers the common mistakes I see, and while I included some tips already, here are some good general tips to sum things up.
The best tips I can give for success:
1) Get a thermometer/humidity reader, you can get these on Amazon and they’re a great way to know what’s going on with your seeds.
2) If you can, get a mini greenhouse, grow lights and heat mat so you can monitor all the conditions as much as possible.
3) Check in regularly, touch the soil to see how moist it is, and if you’re noticing any germination activity.
4) Don’t put all your eggs in one basket, so to speak: Houseplant seeds are tricky to grow, so you really have to find the right conditions in your own home where they can thrive. For that, I recommend trying out different setups. If you have one of those mini-greenhouses that can maintain perfect conditions of somewhere around 70-80F, keep out direct sunlight, provide a good grow light, and maintain humidity, then do that! But most of us don’t have that, so commonly the seeds get started off in nursery pots by a windowsill or outdoors on a patio.
If I could personally go by and see your setups in person, I might be able to point out what spot is best for the seeds or what could be going wrong, but alas that’s not realistic, so experiment! Take the 20 or so seeds and divide them up and plant them in various locations to see what works best. Also try different setups, try out the paper towel method with 5-10, use the rest to pre-soak, then plant in moist soilless mix, cover in a plastic bag and place in different locations where they may get indirect bright light, but perhaps different temperatures. By trying out different setups, you can find what works in your home so you can know exactly what to do for any future plant babies:)
Hopefully that clarifies some things for ya if you’ve been struggling! I’m always here to answer any questions :) Comment below if any of these tips were helpful, what your experiences growing from seed were like, or what conditions you had your seeds that resulted in success. Good luck!
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