indoor seed starting

Get a jump start on spring with seed starting

We may be in the throes of winter here in Northern New Jersey, but we believe it’s never too early to begin planning for spring. Indoor seed starting is a popular and affordable way to begin curating the garden of your dreams. Although the timing isn’t quite right yet where we are, we understand that the planning process takes time. We’ve compiled some guidance and tips we’ve shared with our customers over the years so that you can make the most of these cold winter days before the hustle of springtime yard work. 

Looking for more? We also share hands-on knowledge via our in person classes. Check out our class schedule to sign up for our next germination class at Glenwild Garden Center.


To seed or not to seed?

Indoor seed starting has distinct advantages and disadvantages over purchasing ready-to-plant seedlings from a garden center. 

You can save some money over purchasing live plants by starting perennials from seed… but patience is required. According to the Old Farmers Almanac, purple coneflowers may not bloom for 2-3 years, whereas live plants will often be sold with blooms or buds on them already. It will also take time for the seed-sown patch to fill in, meaning you may have to wait longer for an established garden bed than if you used mature plants. 

On the other hand, indoor seed starting with annuals can be done early enough to ensure full blooms for summer. But some live annuals come with such an affordable price tag, it’s hard to argue the work and supplies required to start them from seed each year. It really just comes down to your needs, your garden’s vision, and your budget.


Plan your garden

When it comes to seeds, there are two predominant categories—edibles and flowers. 

Whether choosing flowers for their beauty, or vegetables for your dinner table, planning your garden ahead of time can prevent a lot of stress and ensure your plants grow their best. Choose a spot in your garden prior to germinating seeds. The location should take into consideration each individual plant’s needs. Be aware of how much sun the space will get once leaves have filled in on the trees, as well as watering needs (and access to water) once your plants are mature. Most seed packets will let you know the plant’s light and other requirements so you can be prepared.

Equally important is to leave room in your garden plan for that amazing vegetable or flower you may stumble across and just have to have.


Choosing what to grow

We say, grow what you like. In other words, if you love daisies, plant them! If you love tomatoes, go with that! It doesn’t matter if you come into the Garden Center already knowing what seeds you want, or if you prefer to take some time perusing the display racks before you decide. This can be helpful for those who need an opportunity to see images of the plants they are considering, or time to review the growing requirements found on the back of the packet. 

Glenwild curates their seeds carefully, choosing only to work with three seed companies they have chosen with research and care. They only carry untreated, non-GMO seeds, as well as organic varieties. The seed racks at the Garden Center are already fully stocked, and although this is a bit early to begin indoor seed starting, having them accessible offers an opportunity to begin the process of garden planning.  


When to start indoor seed planting

It’s easy to get excited about starting seeds this time of year. The days are slowly getting longer and although we’re just settling into the throes of winter, we’re already anxious for the hope of spring. 

However, it’s important to recognize that the general date for planting outdoors in Northern NJ is Mothers Day weekend. Since most plants should be put in the ground within four to six weeks, that equates to at least three months of indoor care, including grow lights, watering, and possibly transplanting if they get too big. 

Additionally, some seeds, particularly cool-weather loving plants, require a direct sow outdoors, and don’t do well if germinated indoors. 

“A beginner’s mistake is that people start too early, and they get tall and leggy,” Jodie said. “The plants don’t want to be indoors forever.”

A good guide for determining when to start your seeds is generally on the back of your seed packet. If the packet doesn’t specifically say how early you should start indoors, then four to six weeks before Mothers Day (when you would ideally want to plant them in the ground) is a good general guideline. That means April 1st in our area.

However, starting in April still requires a little bit of planning. Be sure to gather your supplies and set aside space in your home so that you are prepared. 


Indoor seed starting requirements

With these tools and tips on hand, anyone can start great seedlings indoors!


Germination begins with a good seed starting soil. This is not to be confused with regular potting soil. Although both are sterile, seed starting soil is finer and lighter, giving new roots a better opportunity to burrow and establish themselves. Regular potting soil can be amended with peat moss or vermiculite to create your own seed starter. However, be careful that your potting soil doesn’t have fertilizer in it, as that can be too harsh for tiny seedlings. 

Most importantly, do not use soil from your garden. It is not sterile, and although outdoors the ecosystem will self-correct, in the controlled environment of a pot in your home, natural spores and bacteria can increase rapidly.


Where you start your seeds is as much personal preference as anything else. If you have the right soil, the right temperature for germination, and the right light for growing, your seeds will grow in almost any container. However, there are a few options worth considering.

Many people prefer to use peat pots, or pop up pellets. These do cost more than plastic pots (many of which can be reused from prior gardening experiences, and saved for the following year), but they do require a little bit of extra care during the transplanting process. First, they will need to be removed from their container without damaging the tender root system. This means that the roots need to be established enough to bind the soil in the container together. Using two- to four-inch pots will help in this endeavor. A larger pot will not give the roots enough time to mature before they should be transplanted outdoors. Plastic cell trays, on the other hand, are a great choice for reusable seed-starting. 

Peat pots and pellets eliminate this concern, as they can be planted directly in the soil without having to disturb the roots. However, Jodie rip the bottom of these containers before placing them in the ground to give the roots extra help establishing into the native soil. 

Germination mats and light

Heated germination mats help emulate the warmth of spring. Many seeds require warmth to germinate… this mimics the way the soil will warm under a strong springtime sun, by maintaining even heat all day long. Once the starter leaves (cotyledons) appear, the heating mat is no longer needed. 

This is the time to switch to natural sunlight or a lighting system. The goal is to emulate the amount of light the plants will receive in late spring. To help them get off to a strong start, seedlings may actually need more than the recommended amount of sun indicated on the packet. Because the early spring sun is still weak and low in the sky, that means natural light probably won’t cut it here. This is where a grow light can come in handy.

Grow lights don’t have to be a big set up. Even a small grow bulb in an old lamp, or fluorescent tubes will suffice. The light should be placed only a few inches above the seedlings, if possible, raising the lamp as the seedlings grow. 

Continued care

Watering should be done carefully so as to not wash away the seeds. Bottom watering works well if using seed starting cells or pellets. Larger pots may need to be misted gently to keep the top of the soil (where the seeds are) moist, then switch to bottom watering once the roots have started to mature.


Damping off is one example of a fungus that can destroy a batch of fresh seedlings. This often grows rapidly when seedling trays are overwatered. One way to prevent damping off is to ensure there is air movement around the plants. Jodie suggests a gentle fan. 

Air flow from a fan also can help strengthen the stems of the plants so that they are less susceptible to breakage from wind or rain after they’ve been planted outdoors. Another seedling strengthening exercise is to gently brush the seeds with your hand on a regular basis, like a gentle wind. 


Glenwild’s seed companies

In addition to choosing seeds based on variety and needs, take into consideration whether the seed has been genetically modified, treated, and whether or not it is certified organic. These three companies are the ones Glenwild uses to stock their seed racks.

Renee’s (CA)

Renee’s Garden seeds is run by gardeners, for gardeners and offers only non-GMO varieties (in addition to their non-GMO organic varieties). The line represents owner and founder Renee Shepherd’s personal selection of unusual and heirloom varieties. The individually written packets each include original watercolor art, as well as harvesting information and recipe ideas, among other commonly sought-after information about planting, germination and growing.  The company’s trial gardens test seeds gathered from selected growers across the world, and only plants that offer excellent flavor, color and germinating/growing performance are selected. 


Hart’s (CT)

Founded in 1892, The Hart Seed Company began in the kitchen of Mr. Charles C. Hart as one of six seed companies in Wethersfield, CT. The company expanded to wholesale, then mail order, and finally acquired other companies as it grew. Over 130 years later, it is still run by fifth and sixth generations of Hart family members. They source the highest quality seed available from seed producers across the globe. Each of their varieties are regularly tested for germination rates, and are selected for their production and deer resistance. According to their website, all of their seeds are guaranteed to be free of genetic engineering. 

indoor seed starting can be simple

Hudson Valley Seed Company (NY)

This New York based company combines heirloom and open-pollinated garden seeds alongside beautiful garden-themed contemporary art. Their website is chock-full of information and planting advice. Their artwork is a direct collaboration between gardener and artist. The company selects the varieties, learns their stories, plant, care for and harvest seeds all on their own farms. Then they share these stories with the artists who create a one-of-a-kind original piece of art for each packet sold, representing the journey, love and care gone into each variety and each packet.

As always, if you have any questions or need assistance with your indoor seed starting needs, give us a call or stop by the garden center to get advice from anyone at the shop. And keep an eye out for our next Indoor Seed Starting class. We’re always happy to hear from you!

By Glenwild Gardens