I have a Rugosa grown from seed, in its second summer, grown from seed planted in October 2019, about two feet tall. So far no flowers. Today I re-potted it in a larger pot, about 18 inches diameter and 24 inches deep, with some fresh compost and a little slow release fertiliser. Its roots totally filled the previous pot, which was about 13 inches diameter and 14 inches deep, along with a lavender which I didn’t try to separate it from, as the rootball was so enmeshed and I didn’t want to damage it, and the lavender seems to be supporting it. I cut the lavender back a bit, just the brown bits and took a few cuttings, tidied it up.
I didn’t want to disturb the Rugosa’s roots because the last time I transplanted a Rugosa seedling it didn’t survive. They might be tough things once established, but the seedlings seem quite fragile.
It seems quite healthy, but I am curious what its flowers will be like. How long should it take to flower? Will feeding it rose food, ie more phosphorus and potassium than nitrogen, encourage flowering? I am hoping that the slow release fertiliser isn’t too strong and that it really does release slowly.
Is it ok to leave it in a pot with a lavender? It could be that the lavender’s roots are taking up a lot of the space, in which case it might be better to try to yank out the lavender without disturbing the Rugosa’s roots, or just cut the lavender right back to the woody parts so it will die back, leaving its roots to eventually compost?
Maybe eventually I will have to find an even larger pot for it or try to separate it from the lavender to give its roots enough space. But for now it should be happy, at least it has a bit more room than before.
My rugosa seedlings seem to bloom mostly in their third year, although there have been a few in their second and a couple in their first. I have one that is now in its fourth season and hasn’t bloomed yet (most of these are from two seed parents).
I would think about cutting the lavender off, just to give the Rugosa the best chance possible, but that may have nothing to do with when it blooms.
Duane
RHA Newsletter 9(2): 6-7 (1978)
Rosa Rugosa Hybrids x Miniatures
Lyndon Lyon
A number of years ago, I had a large plant of ‘Thérèse Bugnet’ (R. acicularis x R. rugosa kamtchatica) x (R. amblyotis x R. rugosa plena) x ‘Betty Bland’, also ‘George Will’ (R. rugosa x R. acicularis) x garden roses, and ‘Will Alderman’ (R. rugosa x R. acicularis) x a Hybrid Tea, all in a group. ‘Thérèse Bugnet’ set abundant hips that year and I planted the seed that fall and grew the seedling under fluorescent lights. One seedling and one only blossomed when about 6 weeks old. The flower was semi-double pink, very fragrant, and had plenty of pollen. The plant was upright growing with red stems, thorny at the base and thornless near the top. I started more plants from cuttings as fast as possible and in the spring set then out in a row.
Therese Bugnet has a copy of RoKSNcopia which possibly accounts for that. https://www.nature.com/articles/s41438-021-00512-3
(down the bottom if you click Supplement Table 1 it downloads an excel with all the data)
I wanted to revisit this thread to say thank you for your advice. I did sacrifice the lavender growing in the pot with the Rugosa, and now the Rugosa seems like a very happy, healthy small bush, about two feet tall with beautiful autumn gold leaves. It was obviously the best, maybe only, thing to do for the Rugosa to just cut down the lavender growing in the same pot. (I took cuttings from the lavender, which are still alive, and this variety of lavender seems to need growing afresh often as it quickly gets woody).