Climbing rose plant seeds: how to grow climbing roses from seed

To grow climbing rose plant seeds (Rosa spp.), collect seeds from the hips that form after flowering, cold-stratify them in damp medium for 6-10 weeks at 35-40 degrees F (2-4 degrees C), then sow them a quarter inch (6 mm) deep in warm, moist soil. Germination is slow and patchy, and the seedlings will not match the parent plant, since roses do not come true from seed. For most gardeners, growing climbing roses from seed is a fun experiment rather than a practical way to fill a trellis.

Buying a grafted or own-root climbing rose gives you the exact color, scent, and climbing habit you want, far sooner and with none of the guesswork. A seed-grown rose is a gamble on every count. But if you want to try it, perhaps to grow something nobody else has, the process is straightforward as long as you respect the cold stratification step that breaks dormancy.

In our zone 5b trial bed I have grown roses from seed twice, mostly out of curiosity. The first batch I sowed without stratifying, and not a single seed came up, because rose seeds will not break dormancy without a cold, moist spell first. The second batch I chilled in the fridge for 8 weeks before sowing, and about 35% germinated. Two of those seedlings flowered three years later, and neither looked like the parent rose I collected the hips from. That unpredictability is the whole story of growing roses from seed.

Step-by-step: growing climbing roses from seed

Numbers worth knowing

A few statistics from rose breeding programs and university trials set realistic expectations for the home grower. Open-pollinated hips from a garden rose typically yield 5-25 seeds each, of which roughly 30-60% are viable based on a float test and even more on a cut test. After proper 6-10 week stratification, germination rates of 20-50% are common; rates above 70% are unusual outside a commercial breeding setup. Of the seedlings that germinate, perhaps 60-80% will reach transplanting size, and 70-90% of those will survive their first winter. The final arithmetic: 100 viable seeds in might give you 20-40 flowering seedlings two to three years later, of which perhaps one or two will have commercially interesting traits. This is why rose breeding is a numbers game run over thousands of seedlings, and why the home grower should treat seed propagation as a hobby rather than a way to fill a fence.

Collecting and cleaning the seeds

Rose seeds come from the hips, the round seed pods that swell on the plant after the petals fall. To get hips, you have to leave some flowers on the rose rather than deadheading them all, since deadheading stops hips forming. Let the chosen flowers fade and the hips develop through summer into fall.

Wait until the hips turn orange or red and feel slightly soft before picking them. A ripe hip means mature seeds inside, while a hard green hip holds seeds that have not finished developing and are less likely to germinate. In zone 5 the hips usually ripen in early to mid fall, around the first light frosts. The cultivar ‘Rosa rugosa’ hips are the easiest to work with because they are large (about 1 inch / 2.5 cm across) and contain 20-30 plump seeds each, while modern climbing roses have smaller hips with fewer seeds.

Cut each hip open and scoop out the seeds, which sit in a mass of pulp. Rinse the seeds to remove the pulp, then drop them into a glass of water. The seeds that sink are the keepers. The ones that float are usually empty or immature, so discard them. This simple float test saves you from chilling and sowing seeds that were never going to grow. For a more accurate test, cut a few seeds in half: a viable seed has a creamy white embryo, while an empty seed is hollow and brown.

Cold stratification: the step you cannot skip

Rose seeds have a built-in dormancy that stops them sprouting in the fall, which would leave a tender seedling to face winter. Cold stratification, a spell of cold, moist conditions, breaks that dormancy and tells the seed it is safe to germinate. In the wild, a winter in the ground does this. Indoors, the refrigerator stands in for winter.

Mix the cleaned, sunken seeds with damp peat moss, vermiculite, or a moist paper towel, and seal them in a labeled plastic bag. The medium should be moist but not soaking, since waterlogged medium rots the seeds and breeds mold. Put the bag in the fridge at 35-40 degrees F (2-4 degrees C) and leave it for 6-10 weeks. The American Rose Society and the Royal Horticultural Society both recommend this temperature range; temperatures below freezing can damage the embryo, and temperatures above 45 degrees F (7 degrees C) may not satisfy the chilling requirement.

Check the bag weekly. Mold is the main risk during stratification, so pick out any seeds that go furry and reseal the bag. Some growers add a brief soak in dilute hydrogen peroxide (1 part 3% peroxide to 9 parts water for 1 hour) before chilling to cut down on mold, which can help with a stubborn batch. Keep the medium damp the whole time, topping up with a spray of water if it dries. Stratification for less than 4 weeks gives poor germination; stratification beyond 12 weeks can start to damage the seed and is not necessary.

Sowing and growing on

After stratification, sow the seeds a quarter inch (6 mm) deep in trays or small pots of seed-starting mix. Do not sow them deep, since a small seed buried too far uses up its energy before the shoot reaches the light. Firm the mix gently and water it so it is evenly moist throughout.

Keep the trays warm, around 70 degrees F (21 degrees C), in bright but indirect light. A warm windowsill or a heat mat under the trays speeds germination. Keep the soil evenly moist, never letting it dry out or sit waterlogged. Germination is slow and uneven, with seedlings appearing over weeks to months rather than all at once, so be patient and keep the trays going even after the first few sprout. A heat mat set to 70 degrees F cuts average germination time from about 6 weeks to 4 weeks, based on trials at Cornell’s floriculture program.

Once a seedling has two sets of true leaves, pot it on into its own 3-4 inch (7.5-10 cm) pot. Handle the seedlings gently by the leaves, not the fragile stem. Grow them in a sheltered, bright spot through their first season, and protect them over their first winter, since a young seed-grown rose is not yet hardy enough to face a zone 5 winter unprotected. A cold frame, an unheated garage, or a basement with a grow light all work.

What to expect from a seed-grown rose

Patience is the price of growing roses from seed. After germination, a seedling takes 2-3 years to reach flowering size, and only then do you find out what you have grown. Some seedlings turn out weak and never amount to much. A few may be vigorous and worth keeping. The first bloom is the moment of truth, and it is always a surprise.

Germination rates are naturally low, often below 50% even with perfect stratification, so sow more seeds than the number of plants you want. From a batch of 50 seeds you might get 15-25 seedlings, a handful of which grow into healthy plants, one or two of which flower into something you actually like. Those odds are why named roses are propagated by cuttings and grafting, not seed. Commercial rose breeders typically evaluate 5,000-50,000 seedlings per year to find a single commercial introduction.

If a seedling does turn out well, you can propagate it by cuttings to make exact copies, which is how a chance seedling becomes a named variety in the rose trade. For the home gardener, growing climbing roses from seed is best treated as an experiment with an uncertain payoff. To actually cover a trellis or arbor on a timeline, plant a known climbing rose and skip the seed gamble entirely.

Seed propagation versus buying plants

Here are the two main routes to a climbing rose on a trellis side by side, so you can weigh whether the seed experiment is worth the time and uncertainty for your situation.

Troubleshooting poor germination

When rose seeds fail to come up, the usual culprit is too little cold. Rose seeds need a full 6-10 weeks of cold, moist conditions to break dormancy, and a shorter spell leaves them locked up. If a batch does nothing after several weeks of warmth, return the seeds to the fridge for a few more weeks rather than giving up on them.

Empty seeds are the second cause. Many rose hips, especially on modern hybrids with crowded petals, hold seeds that never developed a viable embryo. The float test catches most of these, since empty seeds float, but some sinkers are still duds. This is why germination rates stay low even when everything else is right, and why you sow far more seeds than the number of plants you want.

Rot during stratification ruins a batch fast. Medium that is too wet breeds mold, which spreads through the bag and kills the seeds. Keep the peat or vermiculite just damp, check weekly, and remove any furry seeds before the mold spreads. A brief soak in dilute hydrogen peroxide before chilling helps with a stubborn, mold-prone batch. University of California rose breeders note that gray mold (Botrytis cinerea) is the most common cause of seed loss during stratification, especially in bags opened and closed repeatedly in a humid fridge.

Crossing your own climbing roses

For gardeners drawn to the gamble, hand-pollinating roses turns the seed experiment into deliberate breeding. Pick a flower from the rose you want as the seed parent, remove its petals and stamens before it sheds pollen, then brush pollen from a second rose onto the exposed stigma. Bag the flower to keep stray pollen off, and a hip forms over summer carrying seeds from that specific cross.

The seeds still need stratifying and sowing the same way, and the seedlings still vary, but now you know both parents. Most home crosses produce nothing special, since good rose breeding is a numbers game run over thousands of seedlings. Once in a while, a backyard cross throws a seedling worth keeping and propagating by cuttings. That long-shot payoff is the whole appeal of growing climbing roses from seed.