{"id":322,"date":"2011-09-29T14:27:35","date_gmt":"2011-09-29T13:27:35","guid":{"rendered":"http:\/\/rumboldayers.wordpress.com\/?p=322"},"modified":"2011-09-29T14:27:35","modified_gmt":"2011-09-29T13:27:35","slug":"is-it-too-late-to-plant-herbaceous-perennials","status":"publish","type":"post","link":"http:\/\/www.rumbold-ayers.co.uk\/blog\/?p=322","title":{"rendered":"Is it too late to plant herbaceous perennials?"},"content":{"rendered":"<p>Last spring Judy and I were invited to visit a newly created garden in Warwickshire that had been planted up the previous autumn, and we were shocked to see many apparently hardy plants had been killed by last winter\u2019s frosts.\u00a0 Obviously, when <a title=\"Rumbold-Ayers planting design\" href=\"http:\/\/www.rumbold-ayers.co.uk\/detailed_drawings_garden_specifications_recontouring.html\" target=\"_blank\">we design a planting plan<\/a>, we are careful to select plants that are suitably hardy.\u00a0 So what caused these plants to succumb last winter?\u00a0 (It wasn&#8217;t one of our designs, by the way.) And if we plant new herbaceous perennials now, will they suffer the same fate this winter?<\/p>\n<p>It&#8217;s the formation of ice crystals, which rupture the plant\u2019s cell walls, that causes frost damage.\u00a0 Some plants are not at all hardy, whilst others are hardy to varying extents.\u00a0 A plant\u2019s ability to withstand freezing temperatures derives from its physiology and acclimatization.\u00a0 Hardy plants use certain \u201ctricks\u201d to help withstand frost, including:<\/p>\n<ul>\n<li>strengthened cell walls;<\/li>\n<li>desiccation: they lower the water content in the cells during the winter (ice in the spaces between cells is much less of a problem for a plant);<\/li>\n<li>natural anti-freeze: they manufacture chemicals inside their cells that inhibit freezing.<\/li>\n<\/ul>\n<p>Importantly, hardy plants generally deploy these survival techniques as a reaction to shortened daylight hours and lower temperatures.\u00a0 This process takes time (which is why locally grown stock is hardier than plants imported from somewhere warmer).\u00a0 New growth is more susceptible as the cell walls are thinner and, by implication, growth means warmth and so less time for acclimatization.<\/p>\n<div id=\"attachment_323\" style=\"width: 326px\" class=\"wp-caption alignleft\"><a href=\"http:\/\/www.rumbold-ayers.co.uk\/blog\/wp-content\/uploads\/2011\/09\/dsc05000.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-323\" class=\"size-medium wp-image-323\" title=\"Geranium &quot;Jolly Bee&quot;, Aster Lutetia and Erygeron Karvinskianus\" src=\"http:\/\/www.rumbold-ayers.co.uk\/blog\/wp-content\/uploads\/2011\/09\/dsc05000.jpg?w=300\" alt=\"Geranium &quot;Jolly Bee&quot;, Aster Lutetia and Erygeron Karvinskianus\" width=\"316\" height=\"201\" \/><\/a><p id=\"caption-attachment-323\" class=\"wp-caption-text\">Geranium &quot;Jolly Bee&quot;, Aster Lutetia and Erygeron Karvinskianus in 9cm pots, waiting to be planted.<\/p><\/div>\n<p>Last winter was characterized by some very severe frosts \u2013 down to -15\u00baC here in south Wiltshire \u2013 and the frosts came in late November, which is early for such severe frost.\u00a0 It was the combination of (early) timing, and severity, which was to blame for the damage.\u00a0 The cold weather also lasted for a considerable time \u2013 several weeks \u2013 which allowed the frost to penetrate deep into the ground, reaching roots that would normally remain frost-free.<\/p>\n<p>And what about soil water content?\u00a0 Well, it is certainly true that wet soil will lose heat much more quickly than dry soil, and so will allow a frost to penetrate deeply.<\/p>\n<p><strong>OK, enough science \u2013 is it too late to plant?<\/strong>\u00a0 No, it isn\u2019t.\u00a0 In fact, as long as the plants are sufficiently mature (not just new growth) and have been properly acclimatized, there is no scientific reason why you shouldn\u2019t be able to plant all year round (as long as the ground isn\u2019t frozen solid!).\u00a0 As they start to go into dormancy, plants are less likely to suffer from the \u201cshock\u201d of transplanting, and there\u2019s still plenty of warmth in the ground at the moment for the roots to get established.\u00a0 Another great advantage is that autumn transplants are much less likely to suffer from drought.\u00a0 Of course, it does all still rely on adequate soil preparation, but that\u2019s another story.<\/p>\n<p>But, and here\u2019s the catch, how do you know if your new plant purchases are acclimatized? Perhaps they arrived on a lorry from the continent only yesterday!\u00a0 (And that little locally propagated 9 cm pot may be much cheaper than a 2 litre pot, but is the plant mature enough to survive a sharp frost? )\u00a0 The one thing I certainly wouldn\u2019t do now is pot on from 9 cm to 2 litre, as the pot will be much more susceptible to frost than a plant in the ground, and it&#8217;s quite likely to put on a growing spurt that just won\u2019t be mature enough to survive weeks of snow and ice.<\/p>\n<div id=\"attachment_324\" style=\"width: 490px\" class=\"wp-caption aligncenter\"><a href=\"http:\/\/www.rumbold-ayers.co.uk\/blog\/wp-content\/uploads\/2011\/09\/dsc05469.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-324\" class=\"size-full wp-image-324 \" title=\"fresh from Italy?\" src=\"http:\/\/www.rumbold-ayers.co.uk\/blog\/wp-content\/uploads\/2011\/09\/dsc05469.jpg\" alt=\"fresh from Italy?\" width=\"480\" height=\"323\" \/><\/a><p id=\"caption-attachment-324\" class=\"wp-caption-text\">........fresh from Italy?<\/p><\/div>\n<p>But if you&#8217;ve prepared the ground well, then I&#8217;d say &#8220;<strong>go for it!<\/strong>&#8220;.\u00a0\u00a0 (And as for what caused the losses in the Warwickshire garden?\u00a0 Well, my money is on plants newly arrived from northern Italy.)<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Last spring Judy and I were invited to visit a newly created garden in Warwickshire that had been planted up the previous autumn, and we were shocked to see many apparently hardy plants had been killed by last winter\u2019s frosts.\u00a0 &hellip; <a href=\"http:\/\/www.rumbold-ayers.co.uk\/blog\/?p=322\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_s2mail":"","footnotes":""},"categories":[10,17,20],"tags":[33,59,68],"class_list":["post-322","post","type-post","status-publish","format-standard","hentry","category-garden-design","category-landscape-design","category-planting","tag-autumn-planting","tag-frost-damage","tag-herbaceous-planting"],"_links":{"self":[{"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/posts\/322","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=322"}],"version-history":[{"count":0,"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/posts\/322\/revisions"}],"wp:attachment":[{"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=322"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=322"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.rumbold-ayers.co.uk\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=322"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}