My Lavender's Brown, Dilly Dilly
June 1, 2010 8:20 AM   Subscribe

What killed my Lavender? Suspects: Cats, weedkiller, poor soil, poor plants or my terrible gardening skills.

Im a gardening noob. I would really like to have a front path lined with Lavender so I recently set about trying to achieve this. It hasnt gone well.

Mature, somewhat neglected south facing garden in SW UK. Soil is clay in the back garden where its shady but the front beds appear to have some quite good drainage and get full sun, the soil is generally dry and stony.

The bed originally contained some Roses and a proliferation of Bluebells, two flowers I really dislike looking at and looking after. I tried digging the Bluebells up last year but I didnt do a good enough job of it and they came back so this year. I got busy with some topical weedkiller and then dug up what was left a week later.

Off I went to B&Q and bought a tray of 10 Lavenders (a French variety I think), they were quite small - about 10cm tall with no flowers. The others on sale seemed to be the same variety but were larger, more established plants in single pots but I went with the tray in order to create my hedge of plants along the path.

A video tutorial on the BBC Gardeners World website said to plant Lavenders with grit below them to help them drain. I had trouble finding 'grit' so settled for a bag of lawn sand.

I created a small bank to help with drainage and planted the Lavenders in holes with a good few handfulls of sand in the bottom. I didnt pack the earth around them too tightly assuming that loose/dry was better and I didnt water them for the same reason (it rained the next day anyway).

The next day I noticed that the bed was being considered sandbox heaven by the local kitties. Two of the plants had been partially excavated. There were paw prints, excavations and poops.

A couple of weeks later and all the Lavenders are brown and the leaves falling off. I scraped some of the bark off the plants in places - theres possibly some life at the base but the outer leaves/stalks are brown on the inside.

So what did I do wrong? Was it the weedkiller? I thought the topical stuff didnt hang around in the soil, a friend who knows more about gardening than I said I didnt need to wait to plant.

Did the local cats spray them? Did I make them too vulnerable by planting them loosely?

Were the plants just too poor quality to start with? Should I have bought larger ones that were already flowering? Was it Lawn Sand a bad idea?

Im planning to try again with a couple of larger plants as see how they fare, but knowing what went wrong would be good. I fear if I kill three attempts then I may give up entirely, Lavender can't be that hard to grow - I see it everywhere!
posted by Ness to Home & Garden (7 answers total)
The fact that they died so quickly suggests to me that they were probably killed off by the combination of lawn sand, destructive cats, and lack of watering. You do know that most lawn sand is usually a mix of iron sulphate, ammonium sulphate and actual sand, don't you? It's used for killing off moss and fertilising lawns. It's not a substitute for grit.

What I would have done:

1. Prepare the soil. If it's heavy clay, mix in plenty of organic matter and break up any large clumps of clay. Water the area well before planting.

2. Make holes and add some grit for drainage, as suggested on the telly. Pea gravel is a bit larger, but will work as well. Sand won't help much, so don't bother with that. Lawn sand is worse than no good - it could well sicken the plants.

3. Plant the lavender, press the earth in nice and firmly around the plants. Loose is not better - the roots need to be able to grow from the compost outwards into your soil.

4. Water whenever the soil looks dry, or when you haven't had rain for a few days. Small plants like these need watering far more than established plants, which have a well-developed root system and will be more drought-tolerant.
posted by le morte de bea arthur at 8:41 AM on June 1, 2010

I remember hearing on Gardeners' World that lavender likes moist but well-drained soil in the summer and in winter it doesn't like having wet feet.

Did you water the plants before you took them out of their garden center trays? They need to be very wet before you transplant them, and tease the roots out before you put them in. The soil does need to be packed and the plants should be watered once they go in.

You definitely need more drainage than lawn sand. Pea gravel is a good suggestion, or even something larger. A layer that's a couple inches deep is probably a good idea.
posted by elsietheeel at 9:07 AM on June 1, 2010

lawn sand is definitley a problem as are cats. Otherwise the aspect and soli sound good for lavender. Once established they need very little care in the UK but it looks like these were not really nurtured in the early days. many of these plants come straight from a forcing greenhouse and a few days out in the front bringing them in at night might also have helped to harden them off. They might just be dying back because of shock.

I suggest digging them up, cut off any drede out twigs back to where there is some green. dig out as much of the lawn sand as you can, and start again. Keep them indoors at night until you see some growth before you replant.

To keep cats off I have broken off thorny brambles or dried branches from the Xmas tree and stuck them around my herb patch in the front garden cos the cats love it. It keeps them away although it looks a bit odd but with a little luck you'll only have to do it till they are really established.
posted by Wilder at 9:17 AM on June 1, 2010

The whole deal with the "grit" and sand and gravel is useless as far as drainage goes. Water moves through soil by capillary action, and when clay soil meets up with sand or gravel, that capillary action stops, and water perches at that transition point. For tiny plants, this means that they stay waterlogged. Only at saturation point would water move into those larger pore spaces, but that happens anyway. In the case of very wet soils in poorly drained landscapes, the water will just pool there for a long time, and a few inches of gravel isn't going to change anything about that planting bed. Until that saturation point though, water remains unable to cross the barrier from soil to sand. This can kill plants that require good drainage. Shorter: it's a myth (article refers to containers, but the principles are the same).

I live in an area in California with heavy clay soil, and we plant lavender all the time without any gravel or sand (in fact, no one plants anything with gravel or sand). The thing to do is to mound it slightly if you have poorly drained soil. This helps the top few inches of soil dry out, preventing root rot.

As to what killed your lavender: I don't know. It depends on the weed killer used, if the root ball was wet when you pulled the plants out, &c. I would start with bigger plants to resist cats. Don't put any gravel in the hole. You can add some compost if your soil is heavy clay, but not more than 25%- frankly it's better for plants to just plant in the native soil and mulch annually with compost, but the average person is psychologically resistant to not putting anything in the hole when they plant things so a little bit of compost won't hurt. (At some point, the roots have to be in the native soil anyway, unless you've turned your entire yard with amendments.)
posted by oneirodynia at 11:42 AM on June 1, 2010

When you plant new plants, dig a bigger hole than you need and put some potting compost in the hole (on top of the grit and to the sides of the plant), topped off with normal garden soil. I use Miracle Gro potting compost, but do NOT put manure-type compost (as in the fertilizer kind) in the soil, or if you do, mix it in proportion of at most 1:10 with garden soil - feeding compost is not the same as potting compost: it burns the roots if it is too strong. A nice potting compost in the planting hole provides a good start with plant feeding and feels more like the soil that nursery plants were grown in (so there is less transplant shock). I'd be inclined to blame the sand - most plants don;t like sandy soil. Miracle Gro really does seem to make plants grow.

As elsietheeel notes, you need to water nursery plants really well before planting them. I usually put them in a big tray (or bucket) of water for at least 30 minutes before planting.
After planting, water at least daily, with lots and lots of water. If your drainage is good (grit in the bottom of the planting hole), you can't overwater. When planting new nursery plants, I use my shoe to press the soil down slightly all around the plant, close to the stem. That ensures that water runs in to the plant and not away from it, when it rains or when you water them.

Finally, it might just be that the plants you bought were too weak. A lot of places keep young plants for far too long and don't care for them. Plants need soil, water, and feeding to survive. A good quality potting compost or fertilized garden soil provides sufficient feeding. But if you keep young plants in the planting tray they were raised in for too long, they don't get enough food. Add to that, that mlost nurseries don;t have enough time or effort to water all the plants regularly and you get sad (wilty) and weak (brown-leaved) plants for sale. So select your next plants carefully. Lavender is quite hardy: mine has survived two winters at -20 degrees.
posted by Susurration at 8:14 PM on June 1, 2010

My understanding of the "grit" (pea gravel, whatever) is not that it's dug into the hole, but that it's used as a mulch to keep the lower branches of the lavender from lying on the damp ground and getting mildewy, which will kill the plant. This general concept has been successful for me--after losing a ridiculous number of lavender plants to mildew, I eventually planted one on a slope with rocks set in all around. The plant has been doing very well for . . . six, seven years now? Pea gravel--or maybe even some of the sharp limestone gravel (the small kind)--around the base of the plants would also deter the kittehs from excavating.

Whether the dampness/mildew was what killed your plants, I do not know; I just thought I'd mention this about the use of the "grit."
posted by miss patrish at 9:20 PM on June 1, 2010

Oh sounds like I did plenty wrong, thank you!

If I hadnt done my research I probably would have gone with instinct and ended up doing a much better job, watered more, packed them in tighter, not used the sand.

With the grit I took a look at the stores website, couldnt find anything that looked right so did some Googling and found forum posts telling people to 'just use any old sand' - which is why I ended up with Lawn Sand - figuring that if you put it on your lawn, how bad could it be?

I've dug up the sad plants and moved them to the back garden, planting them in among other plants in various spots. I plan to revert to my usual gardening style with them - benevolent neglect and see if any of them make it.

I'll try again out the front with your tips in mind.
posted by Ness at 1:17 AM on June 2, 2010

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