World Seed Supply’s Guide to Perfect Poppies

Poppies are some of the most beautiful flowers, and they come in a variety of shapes and colors from black to red to double flowered to peony.  They are almost always grown from seed.  But growing nice-sized healthy poppy plants is highly dependent upon growing conditions.  Temperature, planting depth, spacing and soil can all affect your poppy plants negatively.  In some cases, stressful conditions can signal to a poppy that it is at risk of dying.  In response, your poppies will flower early in an effort to quickly spread some seeds.  This results in little runts that are hardly impressive.  But by adhering to a few simple guidelines, you can end up with that lovely display of poppy blooms that will brighten up your landscape this summer.

Starting Inside vs Outside

Poppies can be grown indoors under lights, but the majority of growers grow them outside.  In general, the poppy is considered an outdoor plant.  So that is what this guide will focus on.  It is common practice with many plant varieties to start seeds indoors as a method of getting a head start on the growing season.  The idea behind this is that you can use the warmth of your house to begin the growing process when outdoor temperatures are otherwise unsuitable.  However, poppies actually tolerate more cold than other plants. In fact, poppies prefer the cool weather. In some cases, they may evenrequire cool temperatures to germinate.   While most of the time poppies will germinate throughout the summer, we have also encountered many cases where growers could not get poppy seeds to germinate until temperatures were reduced.  So if you are starting your poppy seeds later in the season, you may actually want to try the reverse practice of getting a head start.  In other words, you may actually try rewinding the clock back to the cooler months by starting your poppy seeds in the fridge.  This will give your poppies a chance to experience that cool period they like even after the time has passed for it to happen naturally. 

The drawback of starting poppy seeds indoors is that they can easily etiolate (stretch) if not given adequate light.  Etiolation is a plant’s response to low light. It stretches in height hoping to reach up out of a crevice or over competing plants in search of more light.  Many newbie growers will be excited that their plants are rapidly gaining height when this happens, but the quick growth comes at a price.  In order to output more height, the plant has to sacrifice thickness.  This ultimately results in an unstable foundation for the plant to stand on.  Poppies grow as rosettes of lettuce-like foliage.  But if there is etiolation early on, that big mass of foliage will only be connected to the ground by a thin tap root, which can easily snap and cut off the supply of water and nutrients.  Etiolation is especially common indoors, particularly in a dark fridge.  So, other than for the sake of providing cooler temperatures later in the season, it is recommended that growers sow their poppies outdoors.

When to Sow Outside

Outdoor sowing time for poppies depends on your location.  In areas where the winters are relatively mild (zones 7 or warmer), it is best to sow your poppy seeds in the fall or winter.  This will allow the seeds to sprout as soon as the temperatures turn warm enough for poppies to do their thing.  The ideal poppy germination temperature is about 55 degrees Fahrenheit.  Poppy seeds and even poppy seedlings can handle frost, but most information recommends sowing poppy seeds in the early spring for growers in northern locations.  Fall planting is recommended when possible so that you have the seeds in place, but growers in warmer locations can still sow in the spring with plenty of time before conditions turn ideal.  The idea is you want to try to get in as soon as the ground is workable so that you have the longest season possible.   The exposure to cold may also aid germination.  But if you missed fall sowing, don’t let it discourage you from aiming for the spring no matter where you live.

Sunlight

Mature poppies enjoy full sun, meaning at least six hours of direct sun per day.  You can still get flowers in partial sun, but they will be smaller.  But early on, a bit of shade may actually be beneficial.  According to one traditional method, poppies were planted between rows of corn so that they could be shaded by the stalks.  Starting poppy plants in containers allows you to keep the seedlings in a shaded area early on while providing full sun later in the growth cycle.  But if you’re direct sowing, you can always shade your poppy seedlings with other crops, potted plants or even with something like a lawn chair.  Anything that will cast a shadow will help mimic the shade that young plants might experience in the wild.  When you eventually increase the sun exposure for your mature poppy plants, it is best to do it gradually.  Any sudden increases in light exposure always have the chance of shocking a plant.  And if you chose to start your poppy seedlings in containers, be sure to get them used to the full sun environment they will be in before you attempt to transplant.  The combination of transplanting and light increase is a recipe for shock.  If it does not kill your poppies, it could cause serious setbacks.

Direct Sowing vs. Containers

Most information suggests that poppies do not transplant well.  This is true for mature plants, especially because the stems and roots can be somewhat brittle. But poppy seedlings transplant perfectly fine if you do so properly.  Considering this, you have the choice between direct sowing or sowing in containers and then transplanting.  If you’ve started your poppies indoors, then you’ll obviously be transplanting.  But you can also choose to start poppy seeds in containers outside and transplant those seedlings to the ground. 

You might wonder what the point of sowing outdoors in containers instead of direct sowing is.  There are several advantages actually.  Transplanting works better for organization.  You can arrange your poppy plants specifically where you want them whereas direct sowing can give you a more erratic pattern.  The only way around it with direct sowing is if you really sow a lot of poppy seeds and then thin out to exactly where you want each poppy positioned.  But ultimately you will waste more seed doing it that way.  If you have plenty of seed to work with or you do not care about arrangement, then direct sowing is the way to go.  Otherwise, the increased ability to organize is useful.  This is especially apparent if you’re dealing with multiple poppy varieties or other flowers that you want to arrange in a certain pattern. 

Transplanting also offers you a chance to escape insects and weather.   If you’re starting your poppies in a container you have the option of keeping the seedlings out of harm’s way, whether the threat is too much sun, a rain storm or a windy day.  Ants, other insects and birds are known to carry away poppy seeds too.  Just like humans, animals enjoy eating poppy seeds.  While containers can still be occupied by ants, the ground is more likely to house a colony that will walk away with your crop before it ever sprouts.  It is much easier to keep a container out of harm’s way.

Just like insects, wind or rain can ruin your direct sowing job.  Even though the seeds are very tiny, wind usually won’t be too much of a problem unless there are unusual gusts.  But rain is very likely to wash poppy seeds away.  Poppy seeds float easily.  And even your normal watering can cause seeds to pool together and sprout in the depressions of your ground space.  So even if the seeds don’t get completely washed away, you end up having to thin out more than you intended.  Containers give you the option to make adjustments that direct sowing does not.  For one, you can move the containers into a protected area when you’re anticipating bad weather.  Also, transplanting allows you to correct any type of pooling that might occur.

Choosing Soil and Preparing Your Poppy Bed

Now that you’ve considered when and where you want to plant your poppy seeds, it’s time to consider soil.  You want a soil that is very fertile with plenty of organic material.  But it is also essential that it be loose and well-draining.  Poppy seedlings are prone to rot when they are young, so a well-draining mix will be beneficial to prevent that.  A good loamy soil such as compost mixed with sand is ideal.  Some types of poppy naturally grow in dry gravelly soils, but even they will benefit from this more fertile alternative. 

It is important that your soil be loose when you’re growing poppies. Poppies have a taproot that needs to drive downward, and a compact soil will make this tougher to do.  So prior to sowing, it is important that you prepare your poppy bed.  Even if you’re starting your poppy seeds in containers, you still want to prepare your ground.  Till the soil 8” deep over your entire bed to loosen it up and remove any weed roots that may be present.  Otherwise, if you’re starting a new bed, you can till the ground below and add a thick layer of fresh soil over the top.  Either way, you want to aim for 8” of cultivated soil for your poppy roots to grow in. 

Direct Sowing

Direct sow your seeds by scattering them over the surface of your prepared poppy bed.  Aim to broadcast them so that they do not all land too closely together, or you will end up having to thin out seedlings anyway.  Poppy seeds are extremely small, so consider that a pinch contains literally hundreds of seeds.  Not every poppy seed will sprout, and not every sprout will mature, but you do not have to sow as densely as you would with grass seed.  Afterwards, cover your entire growing space with a thin layer of straw about 1”-2” thick as a mulch layer.   We will speak more about mulching later.

Starting in Containers

If you’re starting your poppy seedlings in a container, it is best to use one that is wide.  Aluminum roasting pans are ideal for starting your poppy seeds.  You can fill the pan with a seed starting mix, or you can use the same soil that you’ll eventually be growing in.  Lay the soil flat, but do not compress it. With your index finger, make light depressions about a half inch apart in rows with the same spacing.  Then sow your poppy seeds on the surface of the soil without covering them.  As mentioned earlier, poppy seeds have a tendency to float and collect in the depressions.  By intentionally making the depressions yourself, you can help determine where the poppy seeds will end up and therefore create a more uniform spacing. 

As an alternative to the aluminum tray method, some growers prefer to grow in biodegradable peat pots.   With this method, you only plant a few seeds per pot.  This allows you to transplant the entire pot to the ground so that you can avoid root damage altogether.  The roots can grow through the pot after transplanting.  You can aid transplantation even more if you tear off the bottom, and you can even tear away the entire pot if the roots haven’t grown into it.  One of the drawbacks of using these pots over the tray is that they can dry out easier outdoors. So it is important to keep them regularly hydrated from below. 

Transplanting

Your poppy seedlings will grow together like grass. Allow them to grow as a network until they are about 2”-3” in height. But before you even begin, consider the time of day.  Transplanting is always best done in the late afternoon after the weather has cooled. This will give your poppy seedlings the longest time before they have to face the strong noon sun.  You never want to transplant during the hot part of the day because plants already can be stressed out by the heat.  Even on a day that seems cold, the sun can still have a lot of effect ton seedlings.  Young plants or those with damaged roots are especially vulnerable, and they can fry quickly.  Transplanting during the morning is better than transplanting at noon, but it still means they will have to face the noon sun within a few hours. But if you transplant late in the day, it gives your seedlings all night and the next morning to recuperate. Just be sure to water your poppy bed the following morning so they are well-hydrated for their first brush with the noon sun after transplantation. 

This raises another point.  You always want to make sure your seedlings are well-hydrated before transplanting.  Just like making cuttings, transplanting offers a situation that may decrease the plant’s ability to absorb water. So you want to make sure your reserves are fully stocked ahead of time. Always be sure to fully water your poppy seedling tray about an hour before actually doing any transplanting. This will give the poppies adequate time to suck up what they need before the process begins. 

We mentioned before that poppies have a reputation for being difficult to transplant.  The key to transplanting properly involves doing so at a young age and not damaging the roots.   In order to minimize damage to the poppy’s roots, detach a small clump of poppy seedlings from the main network that you’ll have growing in your tray.  This will help you gather all the soil around one or two central plants in the middle. The plants on the outside will suffer more damage, leaving the plants in the middle relatively protected.  Using an aluminum tray for germination also allows you to go all the way to the bottom so that you can gather all of the soil below the plants without damaging the lower roots. 

Next, dig a hole in your prepared poppy bed that is about twice the size of your root ball and bury your clumps in small mounds that are spaced about 12”-18”.  Most people plant in rows, but feel free to adapt this spacing to a particular pattern or design that you have in mind.  Once the clumps have adjusted to the ground, you want to keep the soil a little on the dry side.  At this point, you will also want to thin out each clump, leaving only the best poppy plants to survive.   

Mulching

Whether you’re transplanting or direct sowing, it is a very good idea to mulch your bed with some straw.  Mulching will help your transplants adapt because it will minimize evaporation from the soil.  For a detailed explanation on the benefits of mulching, you can refer to our article, “Why Mulch?” http://worldseedsupply.org/blog/?p=105  .  But to describe briefly, mulching will help maintain proper soil moisture, help shade young poppy seedlings and help keep your poppy seeds in place during watering or rain.  Many people neglect this step, but it can really make a difference in your success.  If aesthetics are a concern, there are various mulches you can buy.  Otherwise, straw is inexpensive and works great as mulch.  You simply want to cover the entire area between your poppy plants with about a 1”-2” layer of straw.  Mulch right up to the stems of each poppy plant.  As the poppies grow larger, you can thicken the layer.  Ultimately, you should find that this small step makes a difference in your results and cuts down on the effort you will need to put into growing. 

Thinning Out

Crowded poppies must compete for space and will ultimately suffer.  Whether you’re direct sowing or you transplanted clumps of poppy seedlings, you ultimately want to thin out your plant population to reduce competition.  Thinning involves plucking out the competitor plants and leaving only the best poppies to grow to maturity.  Young poppy seedlings will appear as small rosettes that some people compare to lettuce.  At about 2”-3” in height, you want to start thinning out your poppy seedlings.  Early on, poppies can grow fine together, so you do not need to pluck every one right away.   But that is the 2-3” mark is a good time to start the process.  If you’re direct sowing, you’ll have a lot more thinning to do than if you’ve transplanted.  But you will ultimately aim for a final spacing of about 12”-18”.  By the time your poppy seedlings are 4”-5”, you should have a good idea of which ones to thin out and which to leave.  So that is the point when you should have thinned out your bed to the target spacing.  But whereas many growers tend to thin all at once, we suggest a more making-space-as-needed approach until the 4”-5” mark so that you can keep selecting from the best performing poppies. 

Watering

Poppy plants are somewhat prone to rotting, so they should be allowed to dry out between waterings.   Mature plants only need to be watered every several days, especially if you’re mulching.  It is also recommended that you water away from the stem to keep rot to a minimum and to help the roots spread out.  Consider using a soaker hose.  Otherwise, if you’re manually watering, try putting the hose to the ground to soak the soil rather than spraying.  Once the petals have fallen off your poppies, it is common to hold back watering unless the plant appears to be drying out.  This will ensure that the plant and seeds do not rot until they can be harvested.

Fertilizing

Poppies prefer a neutral ph.  Use a fertilizer with a neutral ph to ensure that the ph does not fall below 6.  Most growers use organic fertilizers such as bloodmeal or an organic liquid fertilizer.  Begin fertilization when the plants are about 10” tall.  A fertilizer that is high in phosphorus, which is the middle number in the ratio found on fertilizer packaging, is ideal for poppies.  The nitrogen level, which is the first number, should be comparatively low.  Fertilize your poppies according to the instructions on the packaging of the fertilizer you’re using. 

Harvesting

Each poppy pod can produce hundreds, usually thousands of poppy seeds.  When the crown on the poppy pod stands up and the pod takes on a chalky texture, it is time to harvest.  You can cut the poppy pods from the stems and let them dry in the sun or in a dry area such as a boiler room.  When the poppy pods are dry, cut off the crowns with a pair of scissors.  This will open the top so you can pour out and collect the poppy seeds.  After gathering your whole poppy seed harvest, run it through a strainer to sift out all the broken pod parts.  Even if you’ve harvested a few pods, you should have plenty of seed to grow again the following year.  But just like you thinned out your crop to select the best plants, you should focus your poppy seed collecting on just the best plants.

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