About Plumeria Seeds and Seedlings

Plumeria Seeds

Plumeria seeds may be started indoors. Provide suitable light as seedlings emerge. Base transplanting on root development, crowding, container condition, and safe handling rather than a fixed leaf count. Acclimate seedlings gradually before stronger outdoor exposure. However, starting plumeria indoors is a great way to get an early jump on the outdoor growing season. When choosing a medium in which to germinate plumeria seeds, look for one that says something along the lines of, “seed starting mix.” Check the mix label to determine whether fertilizer is included, and account for nutrients already present before adding any supplemental fertilizer. Seeds can be germinated in many different styles of trays and containers, so choose the type that best fits your space needs. If starting just a few seeds, a simple, flat starting tray or small individual containers will work great. When planting many seeds at once, it may be wise to use trays that are divided into separate growing chambers. This will cut down on the amount of transplanting needed as the plants grow. Successful germination requires viable seed, suitable warmth, moisture, and oxygen. Use a clean, freely draining seed-starting mix that retains moisture without remaining saturated. If additional warmth is needed, use a seed-starting heat mat with temperature control and monitor the medium. Provide suitable lighting as seedlings emerge; do not rely on lamps to regulate root-zone temperature. Insufficient light can cause seedlings to stretch and become leggy. Strong direct sunlight through glass can overheat or scorch unacclimated seedlings. Choose suitable light and monitor temperature rather than treating all windowsill conditions alike. (There are many good plumeria seed germination methods, I suggest you research each one and use the one or ones that fit your situation.)

Soaking is optional. Fresh, viable plumeria seeds can germinate without presoaking when moisture, warmth, and aeration are suitable. If you choose to soak, use clean water and avoid prolonged soaking. Do not use floating or sinking alone to decide whether a seed is viable.

Premoisten the mix evenly and let excess water drain before sowing. Using a tray, spread the seeds so they have about an inch between each, this will help minimize the root damage when transplanting.  I have found using plugs is much easier to handle and preserves the roots when transplanting. There are many good planting methods and you should examine each to see which fits your situation and may help result in higher germination rates. If planting is occurring in a flat starting tray, space seeds at least an inch apart, either in rows or in a grid pattern and cover lightly with 1/4" of growing medium (remember oxygen is important during germination, so don’t pack the medium down too much). Check moisture within the mix rather than judging only its surface. Water gently as needed to maintain moisture without saturation. A humidity cover is optional; inspect covered trays daily and vent or remove the cover as seedlings emerge. Protect covered trays from direct sun and overheating.

Environmental Considerations

As the plumeria seedlings begin to pop up through the soil, there are a few environmental aspects that should be given proper attention right away: light intensity, humidity, and air flow. In my experience, many plumeria seeds emerge in 5–10 days, while some have taken about 30 days. These are observations, not guaranteed limits. Timing varies with seed condition and the growing environment; slow emergence alone does not prove that a seed is nonviable. Plumeria seeds can sprout in total darkness, but, once the seedling breaches the soil, a sufficient light source is imperative. Those first “true leaves” will need a light source to perform photosynthesis and create carbohydrates, which will help sustain both normal plant growth and, most importantly, root growth. Without proper lighting, the early vegetative growth of a plant can be negatively affected and could cause long lasting problems.

Transpiration is the loss of water vapor from a plant, mainly through stomata in its leaves. Humidity, temperature, light, and air movement influence this process. High humidity does not automatically stop root water uptake, but persistently saturated growing medium can limit oxygen around roots. Provide suitable light and gentle air movement, and keep the medium moist without leaving it waterlogged. Vent or remove humidity covers as seedlings emerge, while monitoring moisture.

Air flow and humidity almost go hand in hand. A nice flow of air through the plants’ canopy will encourage the flow of carbon dioxide to the leaves and, subsequently, oxygen away from them. This is not just true for seedlings, but for plants in all stages of growth. A small fan on medium or low can help keep humidity levels low and the heat from any supplemental lighting to a minimum. Be sure to keep the rooting medium moist, but not too wet. Seedlings need water and going too long without can result in serious damage. However, if the medium remains too wet for too long it may impair root growth. As the seedlings grow, they will eventually exhaust any nutrient charge that the growing medium had to offer, so light fertilization may be needed while waiting to transplant into a different container.

As the seedlings grow, with proper care and attention, they inch closer and closer to fulfilling their own unique destiny. Plumeria seedlings can differ from their parents and siblings, but a visibly different flower is not guaranteed. A seedling from a named cultivar is not automatically that cultivar. Record the seed parent when known and keep unknown pollen parentage identified as unknown. As we stand by, eagerly awaiting the flowers of our labor, it is important to remember that every plumeria we grow has entered into this life as a small, almost insignificant looking thing, that so many refer to as simply, just a seed.