Seed Starting Guide
Starting seeds for your own garden can be a very rewarding experience. All it takes is a little patience and practice!
One of the most common myths we hear is that you need a greenhouse to start seeds, but that just isn’t true! On our farm, we use a greenhouse to start our seeds, only because we need a lot of plants! If you are new to starting seeds, indoors is a great place to start. If you don’t have extra space indoors, you can start seeds directly in the garden soil when the temperatures are warm enough.
To start seeds, you first need to decide where you will grow the plants, and then you can gather your materials and supplies to get planting.
Three Ways to Start Seeds
- Inside a Greenhouse
Let's dig into the materials you need for these three different methods.
Indoor Seed Starting
- Multi-tier shelving: Metal shelving from home improvement stores works great for hanging lights.
- Lights for your seedlings: Fluorescent shop lights or LED lights and fixtures with adjustable chains.
- Heating mats (optional): Heating mats under seedling trays can help warm-weather loving seeds to germinate quicker.
- Power source: You will need to be close to a power source to plug in your lights and heating mats. A power strip with a timer attachment is also helpful to have!
Indoor seed starting allows you to start many seedlings in a small space! On the shelves, you can stack a lot of seedlings. Lights are added to each level to mimic sunlight.
Every year, the technology changes on which lights are best to use for seed starting. It is best to do a little research before you purchase lights. For starting seed, you want a bulb with a white/blue color that has a color temperature between 5000-6000 Kelvin. For flowering and fruiting plants, you will want a warmer color temperature in the 4000 Kelvin range. Prices for lights vary widely, so get started with basic lights and purchase better ones after you have a seed starting season under your belt!
Start your lights out two to three inches above your seedling trays and raise them as your seedlings grow taller. You can leave your lights on for 12-16 hours per day and turn them off at night. Attach a timer if needed.
I do not recommend starting your seeds in a windowsill. Usually, windowsills do not get enough direct sunlight, and for that reason, the seeds that germinate can be “leggy” with long, fragile stems. If you decide to start your seeds in a windowsill, a south-facing window will be your best option.
Greenhouse Seed Starting
- Heater: We use an electric oil heater that sits in the center of the greenhouse to heat it evenly.
- Heating mats (optional): Heating mats are optional but can improve and speed germination of warm weather-loving plants (basil, peppers, tomatoes, eggplant, etc.)
- Thermostat with max and min temp functions: Very helpful to keep track of high, low, and current temps inside your greenhouse.
- Power Source: You will need access to a power source. We run an extension cord from the back of our home to our greenhouse.
At Bell Urban Farm, we start all our seedlings in a small 8 x 12 foot Yoderbilt greenhouse (photo on the left.) This is where we start all of our seedlings. It is smaller and incredibly efficient so it costs less for us to heat.
To start seeds in a greenhouse, first you’ll need an area that gets plenty of sunshine throughout the day. Second, invest in a greenhouse that can be weathertight. At night you will close your greenhouse to keep it warm, and during the day, you will open vents and doors as needed for airflow on hot, sunny days.
We start seeds as early as mid-January in our greenhouse at Bell Urban Farm! We keep a very close eye on the seed trays because when the sun comes out, the greenhouse warms up quickly and will need to be vented (opening windows and doors to allow airflow.)
When our seedlings are bigger, we transplant them into larger pots and move them into our new Mindful Farmer high tunnel (photo on the right.)
Outdoor Seed Starting
To start seeds outdoors, you directly sow seeds into your garden. Early spring vegetables like greens and root vegetables like carrots and radish can easily be direct sown into your garden bed in early spring. Summer vegetables and flowers like cucumbers, squash, okra, sunflowers, and zinnias are easy to seed directly into your garden once the temperature warms up.
The pros of direct sowing seeds are that it is the least labor-intensive seed stating option as you quickly put seeds into your garden soil and root development is often the strongest. However, the cons of direct sowing include weather, pests, and weed pressure. You will lose some seedlings to competing weeds and garden pests like bugs, birds, rabbits, or squirrels.
Another option is to start your seeds outdoors in seed trays when the weather is favorable and transfer them into your garden when they are ready. This option allows you to keep a closer eye on your growing seedlings and lets you select their final growing location with more accuracy.
When Do I Start My Seeds?
Vegetables are started at different times of the year, and a lot will depend on what zone you live in. Consult your seed packets to see when it is safe to start certain seeds in your area. Bell Urban Farm is in Central Arkansas, zone 7b/8, and our last frost date is typically around mid-April. Find your USDA hardiness zone by checking out this map. Also, review the most recent Farmers' Almanac to look up your predicted last frost date and first frost date of the year for your zone.
There are two main categories for vegetables: cool weather and warm weather. In Arkansas, we have a long growing season, and you can grow cool-weather crops in the spring and then plant them again in the fall for a late fall or early winter harvest. Radishes, greens, and carrots are good examples of this. Warm weather-loving crops can be planted mid-April and will last until the first frost in late October for us.
Everyone has a different growing zone, and I encourage you to see what other gardeners or farmers around you are planting and when they are planting those crops. Some northern zones may start a seed in the spring, and in the south, we can start them in the fall and overwinter them for an early harvest. It all depends on where you live! Do not be discouraged if you try to start seeds and later find out it was not the right time of year. Gardening is all about learning as you go, making mistakes, and trying again!
Now that you know where to start your seeds, let's talk about the supplies you need!
Supplies for Seed Starting
- Containers, Trays, and Pots
Let's review the supplies you will need to get started.
Soil for Seed Starting
- Bagged mixes: Buy a mix labeled for starting seeds.
- Make your mix! You can also make your seed starting mix:
- 2 parts compost
- 2 parts peat moss or coconut coir
- 1 part perlite or sand
Seed starting mixes are at garden centers, nurseries, and home improvement stores, and they do not need to contain a lot of extra fertilizers.
On our farm, we purchase seed starting mix in bulk from an Arkansas garden center. For a smaller home garden, a couple of bags should be plenty!
Containers for Seed Starting
- Multi-cell trays: These trays allow you to start many seeds at once and conserve space.
- Bottom Trays: Used for watering, especially if starting seeds indoors.
- Soil Blocks: Use a tool called a soil blocker to create your own blocks of soil. A bottom tray is still needed to place your soil blocks in.
- Budget-Friendly Options: Free or low-cost options work too!
- Egg cartons
- Plastic cups
- Cut up toilet paper rolls.
After you plant your seedlings in seed trays, you might need larger pots to “pot-up” your seedlings when they start to outgrow their smaller containers. Grower’s Solution is one of our favorite companies to order seed starting trays and pots. You can also find seed starting containers at home improvement stores.
We typically start our seedlings in multi-cell trays and then transplant them right into the garden when they are ready. However, with the seedlings for our Spring Plant Sale, we will move them into larger 2" - 5" pots to grow bigger for our customers.
The next step in starting seeds is to create labels for your plants. This is especially helpful when you have several different varieties of the same plant.
Write on the labels with a waterproof marker that will not fade in the sunlight (speaking from experience here!) We purchase plant labels for our plants at our plant sale, but we also like using popsicle sticks and cut-up white mini blinds!
Seeds are the most important ingredient!
There are so many options for ordering seeds! You can find them online, at home improvement stores and garden centers, and at a local seed swap in late winter or early spring.
Since we are a farm and grow thousands of seedlings each year, we typically order our seeds online. We focus on non-GMO, Certified Organic seeds. We like to purchase seeds from these companies:
If you intend to save your own seeds after the growing season, be sure to use an open-pollinated variety (more on seed saving in a later blog post!)
Understanding Seed Packets
Seed packets contain essential information to help you figure out when and how to start your seeds. Each variety of vegetable or flower germinates under different conditions. Some may need light to germinate, some may not, some like a specific temperature and need to be planted at a certain depth. The back of the packet will contain all of this information!
We love attending seed swaps to collect new and unique seeds. This photo is from the 2016 Seed Swap at the Faulkner County Library in Conway, Arkansas!
Sometimes you will find seeds that have a history and story behind them! Some seeds have been grown in your local area for generations. These seeds have adapted to your local growing conditions.
Check for upcoming seed swaps in your state and make plans to attend one. New to seed swapping and don’t know what to expect? If you attend a swap, remember to bring envelopes to collect seeds and remember to label them! Take notes on how to start the seeds. We write these directions directly on the envelope to refer to when it is time to plant.
Learn more about the history of seed swaps in the state of Arkansas by watching Seed Swap in the Ozarks, a documentary directed and filmed by Bell Urban Farm co-owner Zack McCannon! Watch here!
Planting Your Seeds
Depending on which method you choose to start your seeds, this may vary a bit for you. At Bell Urban Farm, we use multi-cell trays to start our seeds (usually 72 or more cells). We lightly moisten the seed-starting mix in a wheelbarrow first, then spread it out into our trays. A few sprays will be all you need to moisten the soil in your hand.
Then, we label the trays with the seed type and variety. Remember, consult the seed packet for any information you need (planting depth, temp requirements, light requirements, etc.) Make small indentations in the soil-filled cells, if needed, and then drop the seeds into the cells. When using new seeds, only put one seed per cell. If you are using a seed packet that is a few years old, you may try two seeds per cell to ensure one germinates.
Now, we cover our seeds lightly with more starting mix, unless they are super small and like lots of light to germinate. The seed packet will tell you. Water lightly on top of the whole tray and put onto the heating mat. Since we start our seeds inside a greenhouse, we make sure we have our heater turned on during the cold nights to keep our seedlings warm.
Once your seeds have germinated, you can take them off the heating mat to make room for new trays. Once root development has begun, water the trays from the bottom. Make sure your tray does not have holes in it. The plants will now be forced to develop stronger and deeper roots instead of a root ball near the top of the soil.
We start new seeds almost every week on our farm! Depending on what you are growing in your garden, you may not want to start your seeds at the same time, instead, spread out the seed starting. Start with cool weather-loving crops and then move on to summer crops in the following weeks. Remember to look up your USDA Hardiness Zone, first and last frost date, and consult the info on the seed packets to determine when to start each crop.
Some seedlings grow very quickly, while others may take weeks to germinate and months to get to the size they need to be to plant outside. We like to keep a paper calendar handy to know when to start each plant. We add notes on how they are growing and refer back to it next year when planning our seed starting.
Potting up Seedlings
If you start your seedlings in multi-cell trays, you may need to transfer them into larger pots before it is warm enough for you to plant them into your garden. This activity is what we call potting up or up-potting. In the photos you can see how we are potting up tomato seedlings into 4 inch square pots to sell at our Spring Plant Sale. They will grow in the larger pot for another 3 weeks or so before they are large enough to sell.
Your soil mix for potting up plants needs to contain more nutrients than the soil you used for starting seeds. You can buy another type of potting soil, or you can add some fertilizer to your seed starting mix. We typically add a little compost and feather meal to our mix before we pot up the plants. We will also use fish emulsion to fertilize the seedlings after they are potted up.
You can begin potting up your seedlings once they have grown one or two sets of “true” leaves, the leaves that can perform photosynthesis! The very first leaves of the seedling sprouts are not true leaves. Instead, they are called cotyledons or “seed leaves.” So, wait to pot up the seedling until it has at least two to three sets of true leaves.
Another option is to plant them directly into the garden if the conditions are correct. If the temperature is right to plant them in the garden, don’t worry about potting them up!
Hardening Off Seedlings
If you start your plants indoors or inside a warm greenhouse, you will need to “harden them off” before planting outdoors. Hardening plants off helps them become accustomed to the outdoor temperatures and weather (wind and rain) before being planted in the garden.
Harden seedlings off by taking them outside a week to 10 days before you plan to plant them. Let them adapt to the sunshine, wind, and cooler temps. Start them off in a somewhat sheltered location out of direct sunlight and high wind, then gradually move them into less sheltered areas.
Be sure to keep an eye on the weather because spring thunderstorms can move in fast, and you will need to move your seedlings back under cover if strong winds and rains are predicted.
For the first few days, bring them in at night and then gradually leave them out at night as long as it isn’t too cold.
Above are some photos of seedlings hardening off at Bell Urban Farm. They are placed outside in a partly shady area, and if I intend on keeping them out at night, I will throw a frost cloth on top of them to protect them from the cold.
Don’t give up; enjoy the process, enjoy spending time outdoors and enjoy sharing your garden with friends and family.
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