Sowing Success

There is magic in the work of gardening. Starting seeds indoors brings the promise of summer to early spring long before the outdoors begins to green. “Half the reason I start seeds inside is the joy of germinating. There’s something magical about it,” said avid gardener Janis Russell. “The rest of that is just the fun and joy of watching. It’s not necessary, but it’s good for your soul.”

Russell’s Iowa City yard has been designed to provide respite from the world. It provides varieties of flowers perfect for long-lasting bouquets. Through trial and error and detailed planning, she can provide a dozen reception desks at the University of Iowa Hospitals and Clinics where she works with fresh bouquets from spring through late fall.

“One reason I like using annuals in with my perennials is that annuals tend to bloom longer,” Russell said. “They can provide a continuity of bloom and color in and around the perennials.”

In a younger garden, annuals also help fill the space until perennials mature, she said.

Local garden centers don’t carry every type of flower or filler plant that Russell plants, so she finds starting from seed indoors a must. Starting flower seeds indoors also ensures that her garden will include the varieties and colors she’s designed.

“When I decide on a plant, I want that plant,” she said.

Planning

The joy of watching tiny seedlings take root and thrive offsets the hours spent planning for each summer’s cutting garden, she said.

Russell keeps detailed notes throughout the growing season. She then organizes a notebook with her plan for spring planting based on what went well — and what didn’t the previous season. In winter, she orders seeds from her favorite catalogs and inventories her seed-starting supplies.

The final step is to add seed-starting and transplanting dates to a calendar, staggering dates to avoid becoming overwhelmed.

In March, she begins to enact the detailed plan. By this time in April, Russell already has been busy for weeks planting annual seeds based on her schedule: rudbeckia, celosia and climbing petunias.

Later is better than too soon

Starting seedlings inside later is better than too soon, she said. That way seedlings won’t grow leggy and weak before it warms.

Seed packets tell growers when seeds will tolerate the outdoors. Now is about the right time to start flowers that need four or five weeks indoors before transplanting into a garden or flowerpots. There’s still time to start indoor seedlings for zinnias, bachelor’s buttons, aster, sweet pea and marigolds. That’s because it’s about five weeks before the Corridor’s average last frost date of May 15. Some gardeners plant outdoors on Mother’s Day weekend, but many experienced gardeners advise waiting one more week.

Hedge your success

Zinnias, vital to Russell’s bouquets, can be a bit tricky to start indoors. She said she won’t plant zinnia seeds indoors until May 2. Starting zinnias too soon results in pot-bound plants that resist transplanting, and double-bloom varieties are more likely to result in single blooms, she said.

Russell plants zinnia seeds in small pots made from manure (she calls them “poo pots”). The pot goes straight into the ground, which means the seedling roots won’t be disturbed. As a bonus, the decomposing pots feed hungry zinnias.

“Zinnias take a lot of fertilizers and want a really rich soil,” Russell said.

Russell said she often hedges her success by planting the same seeds indoors and out, surrounded by chicken wire to keep out rabbits and other animals.

“It takes time and work, but you know that it’s wonderful. Every year you just do something more,” Russell said.

This year, she’s trying some new varieties of zinnia: QueenLime Orange and a bicolor zinnia called Aztec Burgundy. She’s adding Victoria Blue salvia and Lighthouse Purple salvia by her garage to de-emphasize a previous red and yellow scheme.

“We’ll see what it looks like. I love playing around with colors and tweaking them,” Russell said.

Starting seeds indoors isn’t complicated, she insists, but there is a process to follow to ensure success. Seed-starting kits come with all the supplies you need except your choice of seeds. A couple of hours of prep at the beginning and daily monitoring of heat, light and moisture are all that it takes, she said.

SUPPLIES

Seeds

You get what you pay for when it comes to seeds. Less expensive seeds often have a lower germination rate and won’t be true to color. Russell said she is partial to Johnny’s Select Seeds because when it comes to color, what you see is what you get. She also saves seeds from some of her favorite plants.

Some seed packets include only a few precious seeds. Others are sold in packs of 100 or even 500. When she has extras, she often gives seeds to friends.

Russell labels each cell with the type of seed planted.

Containers

Start with the size you want to end up with: that’s Russell’s live-and-learn rule. She tried moving seedlings from small containers to larger in the past but doesn’t recommend it because there is too much opportunity to damage roots.

She starts most seeds — other than zinnias — in plastic cell packs. She uses containers with six small cells in a pack. Cell packs need to be flexible enough to push out the seedlings for transplanting. (Most seedlings sold in garden centers are sold in cell packs.)

The cell packs go into flats or shallow trays to allow for bottom watering and keeping them organized.

Seed starting mixture

Start with a sterile seed starting mixture, called starter soil mix, germination medium or seed-starting soil. These soils are lightweight and loose. Also, commercial potting soil or dirt from your yard or garden soil may carry disease.

“You want a very light soil so that their little roots can grow easily,” Russell said.

Do not pack seed starting mixture into cells or pots. Just tamp it down to remove air pockets or let water do the work.

Cover the cell packs with a clear plastic dome, preferably one with vents for ventilation. Otherwise, use regular kitchen plastic wrap.

Heat mats

Flower seed packets often indicate whether the variety likes heat to germinate. Plug-in waterproof heat mats are the answer to replicating the heat of sun-warmed soil.

“I have found it makes a big difference. It’s definitely worth the investment if you want seedlings to survive,” Russell said.

Some inexpensive mats can overheat the seedlings. Monitoring the temperature throughout the day can ensure the seedlings don’t overheat. Or do what Russell does — connect the mats to a thermostat to regulate temperature.

Light

The back of the seed packet will tell you if your seeds, such as petunias or rudbeckia, are light lovers. Artificial light gives the seedlings the healthiest start. Seedlings started in a window are more likely to be leggy and weak or become pot-bound and more apt to fail after transplanting outdoors, she said.

Russell likes a combination of warm and cool bulbs in inexpensive shop lights. She tapes foil with the shiny side toward the plants to reflect more of the light inward.

“That’s very helpful for seedlings that really like light for germination,” she said.

After germination

Once seeds germinate, remove the clear plastic dome. If the dome is dripping with humidity before germination, Russell will cut a few extra holes in the plastic. The trick is to keep the soil moist but not wet. Pour water into the bottom tray below the cell packs. If the soil mixture gets too dry on top, lightly mist with a spray bottle.

Gradually getting tiny plants used to the sun, wind and rain outdoors is called hardening off. Russell takes a vacation so that she’s home to start the process with an hour or two of morning or late afternoon sun. For a week, gradually increase the time outdoors as well as exposure to wind and direct sun.

Russell said you also can start hardening off on a Friday afternoon, gradually adding exposure over the weekend before leaving seedlings outdoors in a protected place the following Monday. She advised keeping the young plants out of the wind and midday sunshine for the first week.

Wait until after the average last frost date to plant seedlings in your garden. Late afternoon is ideal for planting seedlings into your garden or pots, Russell said. This gives the transplants the afternoon, evening and morning to acclimate to the soil before the midday sun hits them.

A step-by-step guide to starting flower seeds indoors

Every gardener has their tips and tricks for starting a garden. These are Janis Russell’s tips for starting flower seeds indoors during the spring.

Measure the soil: I like to measure out the seed starting soil before wetting it. I use 6-pack cells, so get enough. For a 36-cell flat, I measure out six of these into a bucket.

Contain the mess: She uses a bucket to hold the soil, and a white dish underneath the cells as she works with them.

Pre-moisten the soil: Peat-based seed starting mixes will resist water without this step. Lightly spray the soil while mixing by hand, just until moist.

Fill cells: Fill each cell halfway with soil, using a light touch. Don’t pack the soil in.

Water cell packs: Lightly water cell pack until you see air bubbles rising to the surface of the soil.

Drain cell packs: Set each half-filled pack aside for further drainage while filling the rest.

Add more soil: Do this after all packs have been half-filled and set aside for drainage. Take the first one you filled and add more soil until about one-fourth inch from the top. Lightly water the soil until air bubbles rise to the top. Do this with all remaining cell packs.

Set aside cell packs. Let cell packs rest for at least two hours or up to several days.

Planting small seeds: Spread a few seeds onto a plate. Use a toothpick dipped in water to pick up individual seeds. Lightly touch the seed until it adheres to the toothpick.

Using the toothpick, touch the seed to the soil in a prepared cell. The seed should stick to the soil, releasing from the toothpick. Put four or five seeds in each cell, keeping them toward the center and away from the edges. (Eventually, you’ll thin out all but the strongest seedling.) Fill each cell. Do this for each cell pack. Label each cell (or cell pack if all are the same seed.)

Cover seeds or not: Read the seed packet to determine whether your seeds need dark or light to germinate.

Dark-loving seeds: Some seeds, such as gomphrena, like dark to germinate. Cover seeds lightly with soil or vermiculite.

Light-loving seeds: Seeds like petunias and rudbeckias need light for germination, so do not cover with soil; leave the seeds on top of the soil.

Warm cell packs: Place the filled flat of cells on a heat mat. If thermostatically controlled, set to 76 degrees. Cover with a clear plastic humidity-controlled dome. Set a timer on the grow light for at least 14 hours of light per day.

Check plants daily: You should begin to see sprouted seeds as soon as five days.