Once the new year has begun and we wind down from the festivities, Mother Nature in Southern Indiana frequently graces us with warm(-er) and sunny days. It's hard not to drool over the various seed catalogs and dream about getting our hands dirty.
Starting seeds is just one way that many gardeners pass the time between the beginning of the new year and the start of the growing season. Remember, there are many crops that can be grown a bit early and prefer cool weather. Lettuce, spinach, peas, kale, broccoli, etc. are just a few examples. Many of these can also withstand light frosts, but significant cold spells are temperatures dipping below the mid 20s are still too much for these crops to handle. Frost blankets and cold frames can help! We'll post another blog later on showing a few examples to extend your season both in the Spring as well as the Fall.
But for those who want to start their gardening journey, mid to late February is a GREAT time to start some seeds indoors that take a while to germinate or reproduce. I typically start my peppers and tomatoes at this time as well as some flowers and herbs. If the herbs grow too quickly, I can always up-plant them into larger pots or planters. Fast germinating vegetables don't get started until later. To make sure you are planting the right crop at the right time, you can follow a few easy steps. There are plenty of guides online, however they may not be specific to your area. While knowing your USDA Hardiness Zone is a good first start, this will not help you determine your last and first frost dates. Look up the last frost date for your area (you might have to pick the next biggest city if you live in a rural area).
For me, my last frost date (on average...remember, it's not a guarantee) is: April 18
My first frost date in the Fall (on average) is October 24
If I count all the days between April 18 and October 24, I have 188 growing days for fruits/veggies/flowers/herbs that cannot tolerate frost. This is good to know because sometimes you need to choose varieties that ripen sooner if you don't have a very long season (some gourds require over 200 days!).
On the back of the seed packet it should state how soon to start seeds. Some should be direct sown. Carrots are a good example. Since this is a root crop, you don't want to start these seeds and then transplant. They do NOT transplant well and will most definitely die. For me, I'll start carrot seeds in mid March since they can tolerate some cold and if we get hit too hard and I didn't provide them with protection, I can easily start over. If I don't want the hassle of watching the weather or potentially starting over, I would start them after April 18. It's a bit of a gamble and each year is just a bit different. For the perennial flowers listed below, this just means I probably won't get any blooms the first year.
Remember...
Perennial = comes back year after year
Annual = you have to plant each year (only lives one season)
Biannual = only the greens come up the first year, flowers and seeds/berries are the second year and then the plant dies.
For all the rest of the garden I plant, I try to count backwards from the last frost date and start seeds accordingly. To help with germination, a heat mat and grow lights are important but not 100% necessary. Tomatoes and peppers require warm temperatures...it's easier to turn on a heat mat than have my house at 75+F. Make sure you use a good quality seed starting mix. You can either make your own or purchase from the store. I typically purchase because it's easier and I look for them to go on sale at the end of the previous season. Seed starting mix is different from potting mix, raised bed mix, garden mix, top soil, etc. There aren't a lot of nutrients in seed starting mix because the baby seedling obtains most of its nutrients from the seed itself. If it has too many nutrients, the seeds will grow too quickly, become leggy and/or sick and most likely die. More nutrients will be needed as the seedling grows, but that typically takes a few weeks.
When starting new seeds, I like to take a kettle of very hot water and mix with the seed starting mix. This will help hydrate the mix and evenly water the seed/seedling. I use very hot water to help kill any bug eggs, etc. that might be living in the mix. A little water goes a long way, so add a little, stir, then add some more if needed. Seeds can be started in a variety of containers--you don't have to have any special growing cells. They might make some of the organization a bit easier, but don't let the lack of having them stop you from starting seeds. SOLO cups are a good container as are washed out yogurt cups. Just make sure you punch/drill a few drainage holes in the bottom of anything you use. Have plant labels ready to go! You can do this a few different ways, but I like to use a combination of color coded containers (yup, I have that many), painters tape, and little markers you stick in the soil. It all depends on the type of container I'm using.
Look on your seed packet and see if there are any special instructions. They will tell you how deep to sow your seeds (don't fret too much, eyeballing is ok!) and remember that some seeds need light to germinate. You'll sprinkle these on top and gently press into the soil.
After I've buried the seeds, I cover the entire container with a clear dome. This helps keep in the humidity and heat the kickstart the germination process. My soil mix stays evenly moist, which is what is needed at this stage. If it dries out too quickly, the seeds/seedlings may perish.
Once my plant has two sets of true leaves (not counting the first set of leaves that sprout), then I remove the dome portion and make a point of ensuring the plant is watered when needed. Once the dome is removed, I add an oscillating fan to simulate wind. This will create stronger stems. The lights should only be about 2 inches from the top of the plants to reduce legginess (when plants are 'reaching' for the light). At this time, I might let the soil dry out between waterings...but just for a day or two. At some point, my plants will outgrow the 6-cell container I used to start. At this time, I'll up-pot (use a slightly bigger pot) to give the roots room to grow and spread out. You don't want to shock your plant by giving them too much space too soon. It's more hands on, but slowly up-potting is better for your plant (and you get to play in the dirt more often, which is a double win!).
With my tomato seedlings, I will bury them deeper in the new pot, bringing the soil level up to the first set of true leaves, if possible. By burying the lower leaves, these turn into roots on tomato plants. The same is NOT true for peppers, so make sure you transplant them at about the same level as the original container. During this time of transplanting, you should either separate multiple plants from one container and plant individually or snip/pinch off the weaker plant. This second option is really hard to do! If you leave both plants together, as they grow, neither will flourish to its fullest potential. I usually separate and plant individually with the idea that I can always try and sneak in an extra plant here and there throughout the garden or give to friends if/when I truly run out of room.
Everyone's seed starting set up is different. I don't have the window space for the amount of seeds I start and none of them are facing in the right direction for long periods of direct sunlight. My set up is in the basement with grow lights and fans on timers and a heat mat that is constantly plugged in. Once the seedlings are bigger and the weather outside stabilizes, I will place them outside on nice days to get use to the sunshine. We'll talk about hardening off processes later in the season.
Some FAQ...
Do I need to buy the expensive grow lights? Nope. Regular shop lights will work. Remember, there's the 'will work' and 'will work better' when it comes to gardening. This can quickly become a pricy hobby, but if you have friends and family who need a good Christmas/birthday present, you might suggest a grow light. Accumulate them slowly and the cost isn't as big of an issue. Seeds and seedlings typically use more blue-green light. Look for bulbs in the 400-490nm spectrum (it'll say it on the box). Once the seedling starts producing fruit, then it switches and uses more of the red light spectrum (by then, these guys will be outside and you shouldn't have to worry about it. Using LED is a good way to lower your energy bill but still have this experience. One word of caution, do not buy the strip of lights that come with a remove and you can do the color change option. These $10-ish dollar lights are great for around windows or for parties, but do not give off enough lumens to satisfy your plants needs. By all means, give it a try, but take it from someone who had to nurse back a rack full of sick plants, it wasn't worth it.
How close should the lights be to the plants? The lights should be really close to the plants to prevent them from reaching. The general consensus is about 2 inches above the tallest plant. Remember, plants will continue to grow, so having an adjustable system is helpful.
How long to I keep the lights on? There's no good answer to this. I try and mimic a summer day, so I'll keep the lights on for about 14 hours/day. A timer works well for this so you don't have to remember to turn the lights on/off.
What type of heat mat do I need? I have a generic heat mat that warms up when plugged in. There is no thermostat and you can barely feel a temperature difference when you put your hand on the mat. However, it seems to really make a difference with the plants--for the sake of experimenting, I've tried both with and without the heat mat. Faster germination and better growth while on the mat for sure! I got mine off of Amazon and didn't spend an arm/leg. I've had the same mat for 5+years.
How long do I keep the heat mat on? I turn mine off after all my seedlings have sprouted and all domes are removed. Since I'm constantly starting new seeds, it's pretty much on from mid-Feb. until end of March.
What type of fan do you use? Do I have to use one? I have a tower fan that I brought home after Covid sent us home to telework. It's what I had, and so it's what I use. You can use any type of fan, the point is to make the plants wave back and forth a bit so their stems grow strong. I like mine to oscillate so it reaches all plants on the shelving unit and it's on the same timer as my lights. That way the plants do get a few hours break from the wind. Again, no hard and fast rule, just stimulation for the plants. Sometimes I go in there an turn it off as I work and forget to turn it back on for a day or so. Not a big deal. It's not necessary to have, but it's a nice addition and I do think it makes for stronger and healthier plants.