Testing Seed Starters for Spring Seedlings

article image
PHOTO: JEFF MERMELSTEIN
The standard depth is three inches for seedlings that will stay in the starter for up to a month and six inches for those that will remain from four to six weeks.

A close look at eight home gardening seed starters for your spring garden. 

Testing Seed Starters for Spring Seedlings

Peat Pot

Description: Individual square or round
pots made of pressed peat moss and plant nutrients. A
popular brand called Jiffy Pots can be bought in connected
groups of 12, called Jiffy Strips. They are used with
standard plastic flats or specially sized Jiffy Set
flats.

Durability: One-time use. Peat pots are
meant to break down in the soil.

Ease of use: These plant-it-all containers
have been popular with home gardeners for a good while, but
I noticed a few potential drawbacks. Round pots seem a
waste of space when compared to square ones. Individual
pots are a pain to keep standing when you’re filling them
(sets are easier). And the peat walls tend to wick water
away from the soil. Granted, this does promote good
drainage and root aeration, but the extra waterings thus
required promote algae growth, as well. You also need to
tear peat pots when transplanting (they don’t always break
down readily), and you should bury them
completely–any edge left above the surface will wick
moisture away from the root zone.

Access: Local garden nurseries and many
seed and garden supply catalogues, including Park Seeds
(Greenwood, SC7). Eight Jiffy Strips (a
total of 96 pots) cost $5.95 plus $1 shipping and
handling.

Rating: * * Peat pots require too much
watering and can be inconvenient to use.

Soil Block Maker

Description: Spring-loaded metal devices
used to produce cubes of soil for individual seeds. The
plant cubes are then transplanted into the soil. Flats for
these soil cubes can be wooden (with three walls to allow
easy block removal), plastic or even the venerable
half-gallon milk carton (cut in half longways, each half
will hold exactly eight cubes).

Durability: The block maker should last
indefinitely if well cared for. Individual soil blocks are
used only once.

Ease of use: The key to success with block
makers is the soil mix you use. It must contain enough peat
moss to hold the cubes together without their becoming
adobe hard. Nick Woodin, a market gardener in New York, has
had success with a mixture of 50% peat moss, 50% compost
and some lime to adjust the pH.

Watering can also be a bit tricky. Since each cube stands
alone, the plants need to be watered frequently. Yet
overhead watering must be gentle to avoid eroding the
blocks, while watering from underneath, using capillary
moisture, will cause the bottoms of the blocks to become
mushy if too much moisture is present.

You can make as many or as few soil cubes as you need, and
the long-lasting tool pays for itself in one or two
seasons. But don’t leave seedlings in soil blocks for much
more than four to six weeks, as they’re too shallow to
support extended growth.

Access:  Some garden supply centers, as
well as Gardener’s Supply (Burlington,
VT) for $14.75 plus $2.75 for shipping and
handling.

Rating: * * I like the concept, but my
blocks don’t stand up well to repeated waterings.

Wooden Flat

Description: Rectangular wooden container with slatted
bottom boards spaced 1/8 inch to 1/16 inch apart for
drainage. The standard depth is three inches for seedlings
that will stay in the starter for up to a month and six
inches for those that will remain from four to six weeks.

Durability: A flat will last many seasons
if properly cleaned and stored between uses.

Ease of Use: Convenient to use. (But don’t
make them too big or they’ll get heavy. Good sizes are 14
by 23 inches for the three-inch-deep flats and 14 by 12
inches for the six-inch-deep containers.) Line the bottom
of each flat with whole leaves or newspaper. Fill it with
soil mix, and sow. For indoor use, you’ll need a cookie
tray or something similar to catch the run-of from
watering. You may want to transplant seedlings started in a
shallow flat to a larger one as they grow (a process called
pricking out).

Transplanting, which requires lifting out sections of soil
and seedlings and gently sorting out individual plants,
isn’t as easy as it is when using the other seven systems,
but the small amount of natural pruning that ensues
actually encourages lush root growth.

Access: Homemade. You can build them for
free from scrap wood, or use purchased redwood or cedar
boards.

Rating:* * * * My favorite seed-starter.
It’s attractive, is a cinch to make at home out of natural,
recyclable materials and gives plant roots plenty of room
to grow.

Plastic Pack

Description: One-piece, pocketed plastic
sheets. The common size has six cells to a pack (the more
cells per pack, the smaller each one will be), and eight of
these packs fit into one flat.

Durability: Extremely flimsy, yet made from non-recyclable
materials.

Ease of use: Convenient to use. The soil doesn’t dry out too quickly in
between waterings, and transplants pop out with no damage
to the roots. One thing you must be watchful for is plants
becoming root-bound. This happens sometimes, especially
with smaller cell sizes, and can cause poor development or
premature bolting.

Access: Inexpensive packs cost around 50 cents a flat. W. Atlee
Burpee Company (Warminster, PA 18974) sells Deep Root
6-Packs, which are more durable than garden center packs. A
set of 10 6-Packs (for 60 seedlings in all) goes for $4.95
plus $1 shipping and handling.

Rating: * Plastic packs work all right–I just can’t stand the
environmental implications of such blatant throwaway
thinking.

Accelerated Propagation System

Description: A very neat, compact system,
consisting of six parts: a bottom reservoir, a plastic
liner, a stand (that doubles as a pegboard for ease of
popping out seedlings at transplant time), a special
water-wicking mat, the actual growing tray and a clear,
plastic greenhouse-like cover to keep in moisture and
warmth.

Durability: Should last many
seasons.

Ease of use: Easy to fill, plant and
transport. The reservoir holds almost a gallon of water,
and the capillary mat that hangs into it makes this water
available to the roots, which can draw from it as needed.
Therefore, the APS can be left alone for days at a time
once seedlings are growing well.

The APS-40 has 40 one and one-halfinchsquare cells and is
recommended for lettuce, onions, leeks and celery, as well
as some herbs and flowers. The APS-24 has two dozen
two-inch-square cells and is recommended for plants needing
more growing room, like tomatoes, peppers, brassicas,
melons and corn.

Access: Available from Gardener’s Supply
(Burlington, VT). Each unit costs
$7.95 plus $2.75 for shipping and handling; a set of three
units is $21.50 plus $4.95.

Rating: * * * The APS is especially
convenient because it waters itself. Plants did so well I
had to take two weeks off recommended starting times.

Speedling

Description: Solid, one-piece, polystyrene
trays with pyramid-shaped cells. The square tops of these
cells funnel down to holes the diameter of a pencil.

Durability: The one-piece unit will last
for 20 plantings or more. It is used repeatedly by many
commercial growers.

Ease of use: Speedling cells are a breeze
to fill with soil. If you use the unit indoors, you need to
rig some kind of tray (such as an oversized cookie sheet)
to catch draining water. You may also want to prop the unit
up on small blocks to help “airprune” the roots. The thick
polystyrene walls insulate the soil pyramids, retaining
heat and moisture. This helps keep the soil from drying out
too quickly, which could mean death to tiny seedlings. The
stout young plants are a cinch to remove (just poke a
pencil eraser through the bottom holes) and
transplant.

Access: Peaceful Valley Farm Supply (Nevada City, CA). The Model 200,
which has 72 cells, two inches square by three inches deep,
is a good all-around size. It costs $6 plus $2 for UPS
shipping ($4 shipping for multiples of four).

Rating: * * * Easy to use, durable and
effective. Peaceful Valley states, “We’ve noticed 100076 to
300076 more roots with Speedlings than with other
systems.”

Park Starts

Descriptions: A compact polystyrene
seed-starting block with 18 cells. The block measures only
two and a half inches wide by six inches long by three
inches deep. The small (less then 3/a inch wide) planting
cells come prefilled with peat-based plugs.

Durability: One-time use. Park-Starts are
not meant to be refilled.

Ease of Use: There
is no making or adding soil mix with this system. You just
drop the seeds in, water with the provided soluble plant
food and keep in a lighted place. However, it can be hard
to get average or small seeds into the small but deep holes
in the plugs. Many that do not get into the holes will not
survive. On the other hand, some seeds that do get into the
holes rot while large seeds won’t fit the holes at all.

Park-Starts are intended for short-term seedling growth, no
more than three or four weeks. This, however, doesn’t allow
for the indoor jump on the season of from six to eight
weeks that most seed-starting gardeners are after.

The included tray provides a very small water reservoir, so
the soil plugs dry out very quickly. Often they needed
watering twice daily.

Access: Available from Park Seeds
(Cokesbury Rd., Greenwood, SC 29647). Each pack contains
three units, will start 54 seedlings and sells for $5.95
plus $1 shipping and handling.

Rating: * Inconvenient to use and
nonrecyclable. Worst of all, seedlings grown in ParkStarts
were consistently smaller than those grown with the other
systems.

PaperPots

Description: Rings of biodegradable paper
joined in a honeycomb pattern with waterproof glue. These
rings come in three different sizes and packages include a
white plastic tray.

Durability: One-time use. The rings are
planted directly in the soil.

Ease of Use: This system requires a bit of
care to fill. Each set of pots is shipped as a very thin,
flat rectangle. You stretch it open, accordion style, then
clip it to the edges of the plastic flat while you fill the
rings with soil. You have to make sure the pots are resting
on the bottoms of the flats, then aim the soil into the
pots, avoiding the oddshaped empty spaces that may occur
around the edges. (Or you can just fill the whole tray and
plant in the spaces as well.)

You need to tear the pots when transplanting in case they
don’t break down quickly. PaperPots are good for staggered
plantings, since you can remove only a few seedlings at a
time. And the closeness of the pots to one another
conserves moisture and helps retain warmth.

Access: The complete PaperPot system
includes three trays and 240 pots in a range of sizes for
$15.95 plus $3.75 shipping and handling from Gardener’s
Supply (Burlington, VT).

Rating: * * The pots are non-reusuable and a bother to set up and fill.